MANOBS Manual of Surface Weather Observations: recording the hourly observations on form 63-2322

10.1 General

The following instructions deal with entries in the various lines and columns of Form 63-2322, although not necessarily in the order in which the elements are observed or that the entries will be made by the observer; For example, the type of report is usually determined after all other data have been observed.

10.2 Section II - hourly observations "UTC"

10.2.1 Column 23 - corrected wet-bulb

Enter the corrected wet-bulb temperature to the nearest tenth degree Celsius. Leave this column blank when the dewpoint is obtained from the MSC dewcel.

10.2.1.1

When the corrected dry-bulb temperature is lower than -37°C, enter "M " in Column 23.

10.2.1.2

Add "NV " in this column at each hourly observation that the psychrometer motor is unserviceable. If the psychrometer motor is unserviceable for more than a day add "NV " once each day at the time of the first scheduled observation and explain under "Notes and Instrument Defects and Changes," Column 1 (at those stations not equipped with a sling psychrometer).

10.2.2 Column 24 - relative humidity

Enter the relative humidity as a percentage if there is a regional or local need, otherwise this column may be left blank (see 6.7).

10.2.3 Column 25 - total opacity

Enter, in tenths of the whole sky, the total opacity for all layers. This cannot exceed 10 tenths. If blue sky or stars are visible, the total opacity shall not exceed 9/10.

10.2.4 Column 26 - total amount

Enter, in tenths of the whole sky, the sum of the amounts for all layers. In determining the total amount, disregard portions of upper layers which are seen through transparencies in lower layers (the total amount cannot exceed 10 tenths).

Note: In determining total opacity and total amount (25 and 26), any layer whose amount is a trace shall be disregarded (e.g. Trace of cumulus in each observation):

Example of entries in 2322 form (See long description below)
Description of image

This table indicates where the recording of Total Amount and Total Opacity shall be recorded on Form 63-2322 and provides sample entries for sky condition and obscuring phenomena.

10.2.5 Column 27 - type of report

Enter one of the following to indicate the type of report:

  • SA for Hourly
  • SP for SPECI
  • C for Check

Note: For criteria for determining the various types of reports, see 10.3.

10.2.6 Column 28 - date (UTC)

Using two digits, enter the date of each observation, specials and checks included, based on Coordinated Universal Time (UTC). For example, if an observation is recorded at 2300 UTC on the 9th of the month, enter 09. For the observation one hour later at 0000 UTC , the date would be entered as 10. The change of date shall take place at 0000 UTC.

10.2.7 Column 29 - hour (UTC)

Using a four-digit group enter the Coordinated Universal Time (UTC) of the observation.

10.2.7.1 Time assigned to SPECI observations

The time assigned to a SPECI observation shall be the time at which the element necessitating the SPECI was observed (except in the case of end of thunderstorm or precipitation, see 10.3.5.5 and 10.3.5.6). If more than one element has changed sufficiently to cause a SPECI , the time shall be the time of observation of the element considered to be most important to aviation.

10.2.7.2 Time assigned to Check observations

The time assigned to a Check observation shall be the time at which the observation was completed.

10.2.8 Column 30 - sky condition

10.2.8.1 Sky cover - terms and abbreviations

Sky Cover - Terms and Abbreviations
Term Symbol abbreviation Symbol used to represent
Clear CLR The sky condition when no cloud or obscuring phenomenon is present.
Partially obscured -X A surface-based layer with summation opacity of at least 1/10 but less than 10/10.
Obscured X A surface-based layer with a summation opacity of 10/10.
Few1 FEW A layer aloft with a summation amount of 3/10 or less.
Scattered1 SCT A layer aloft with a summation amount of 4/10 to 5/10 inclusive.
Broken1 BKN A layer aloft with a summation amount of 6/10 to 9/10 inclusive.
Overcast1 OVC A layer aloft with a summation amount of 10/10.

Return to note1

Note: The symbol for "thin" (-) may be prefixed to these symbols (see 10.2.8.2).

10.2.8.2 Thin layers

A layer aloft shall be described as "thin" when both:

  1. The summation amount of the layer exceeds the summation opacity of the layer by 1/10 or more of the whole sky; and
  2. The summation opacity of the layer is 5/10 or less of the whole sky.

10.2.8.3 Order of sky cover symbols and/or contractions

A sky cover symbol shall be recorded for each layer observed. Multiple layers shall be reported in order of their height, starting with the lowest. When used in combination with other abbreviations, -X (partially obscured) shall be reported first, and X (obscured) shall be reported last.

Note: -X and X shall not be used in the same report.

10.2.8.4 Heights of layers aloft

A coded numerical value, giving the height of the base of the layer aloft, shall be prefixed (with one space) to FEW , SCT , BKN or OVC. Heights are with reference to the official aerodrome level of the station, or, if this has not been established, with reference to the ground level.

10.2.8.5 Vertical visibility

A coded numerical value giving the height of the vertical visibility in a surface-based layer shall be prefixed (with one space) to the symbol "X".

10.2.8.6 How to obtain the coded height:

  1. Heights of bases of layers or height of vertical visibility shall first be determined to the nearest:
    1. 30 m from the surface up to 3000 m; i.e., 0 m, 30 m, 60 m, 90 m, 120 m etc.
    2. 300 m above 3000 m; i.e., 3000 m, 3300 m, 3600 m, 3900 m, etc.
  2. After the height has been determined to the nearest 30 m, or 300 m (see 10.2.8.6 (1) ) this value shall be divided by 30 to obtain the coded height which will precede with one space the symbol FEW , SCT , BKN , OVC or X; see 10.2.8.4.
  3. If the actual observed height is exactly halfway between any two values which satisfy the increments in 10.2.8.6 (1), the lower value shall be used to obtain the coded height: e.g., the coded height of a layer based at 75 m would be 2, i.e., 60 ÷ 30.
10.2.8.6.1

Example:

Table of how to calculate coded height
Height of base of layer Coded height Equivalent height in feet1
30 m 1 98
120 m 4 393
1500 m 50 4921
6000 m 200 19686
9000 m 300 29529

1 Note: The coded height recorded in Column 30 is a direct reading of height in units of 30 meters and is a close approximation of the height in hundreds of feet.

10.2.8.6.2

One space shall be used between the coded height and the contraction or symbol, and one space shall be used to separate the data which apply to one layer from the data which apply to the next higher layer.

Example:

Example of entries in 2322 form
Description of image

This is an example of sky condition entries and illustrates that one space shall be used between the coded height and the contraction or symbol, and one space shall be used to separate the data which apply to one layer from the data which apply to the next higher layer.


View larger image

10.2.8.6.3

When heights referring to surface-based layers or to layers aloft are given in the "Remarks" of the hourly observation (see 10.2.19.2), the heights shall be expressed as coded heights, see 10.2.8.6. If the observer has confidence in the accuracy of a height available to them, the height reported in "Remarks" should be expressed in feet to the accuracy available.

Example: CIG 140 FT.

10.2.8.6.4
Table calculating height in metres to coded height
Metres Coded height Metres Coded height
<16 0 1200 40
30 1 1230 41
60 2 1260 42
90 3 1290 43
120 4 1320 44
150 5 1350 45
180 6 1380 46
210 7 1410 47
240 8 1440 48
270 9 1470 49
300 10 1500 50
330 11 1530 51
360 12 1560 52
390 13 1590 53
420 14 1620 54
450 15 1650 55
480 16 1680 56
510 17 1710 57
540 18 1740 58
570 19 1770 59
600 20 1800 60
630 21 1830 61
660 22 1860 62
690 23 1890 63
720 24 1920 64
750 25 1950 65
780 26 1980 66
810 27 2010 67
840 28 2040 68
870 29 2070 69
900 30 2100 70
930 31 2130 71
960 32 2160 72
990 33 2190 73
1020 34 2220 74
1050 35 2250 75
1080 36 2280 76
1110 37 2310 77
1140 38 2340 78
1170 39 2370 79
Table calculating height in metres to coded height
Metres Coded height Metres Coded height
2400 80 9000 300
2430 81 9300 310
2460 82 9600 320
2490 83 9900 330
2520 84 10200 340
2550 85 10500 350
2580 86 10800 360
2610 87 11100 370
2640 88 11400 380
2670 89 11700 390
2700 90 12000 400
2730 91 12300 410
2760 92 12600 420
2790 93 12900 430
2820 94 13200 440
2850 95 13500 450
2880 96 13800 460
2910 97 14100 470
2940 98 14400 480
2970 99 14700 490
3000 100 15000 500
3300 110 15300 510
3600 120 15600 520
3900 130 15900 530
4200 140 16200 540
4500 150 16500 550
4800 160 16800 560
5100 170 17100 570
5400 180 17400 580
5700 190 17700 590
6000 200 18000 600
6300 210 18300 610
6600 220 18600 620
6900 230 18900 630
7200 240 19200 640
7500 250 19500 650
7800 260 19800 660
8100 270 20100 670
8400 280 20400 680
8700 290 20700 690
    21000 700

10.2.8.7 Ceiling definition

The ceiling is the lesser of:

  1. The height above ground of the base of the lowest layer aloft at which the summation opacity is 6/10 or more of the whole sky.
  2. The vertical visibility into a surface-based layer which completely obscures the sky.

Note: When the sky condition is such that neither of the above conditions is satisfied, the ceiling is said to be "unlimited."

10.2.8.7.1

The summation opacity is the sum of the opacity of a given layer and the opacities of all lower layers. Thus, the layer which constitutes the ceiling may be determined by adding up the opacities of individual layers, until 6/10 or more is reached. However, the second part of the ceiling definition should be noted. If a layer is surface-based and its opacity is less than 10/10, the surface-based layer cannot constitute a ceiling. Thus, surface-based layers must have an opacity, or summation opacity, of 10/10 in order to constitute the ceiling layer. For example, if 6/10 of fog were present, it would not constitute the ceiling layer, but if there were 1/10 Altocumulus cloud above the fog, making the summation opacity 7/10 at the level of the Altocumulus, the Altocumulus would constitute the ceiling layer and its height would be reported as the ceiling in Column 30.

10.2.8.8 Measurement of ceiling

The determination of the ceiling is an extremely important part of the observation. At stations so equipped, the laser ceilometer shall be used at each observation. At stations not equipped with a laser ceilometer the following procedures apply:

  1. During the hours of darkness, the ceiling projector shall be used at each observation.
  2. During daylight hours, a ceiling balloon shall be used when the ceiling is estimated to be 300 m or less (coded height 10). Should there be any doubt whether the ceiling is above or below 300 m (coded height 10) a balloon shall be used.
  3. During daylight hours, a ceiling balloon shall be used whenever requested by a forecast office or responsible flight personnel (such as pilots, Air Traffic Control (ATC), Flight Service Station (FSS)).
  4. During daylight hours, when the ceiling is estimated to be more than 300 m (coded height 10), a ceiling balloon may be used on the initiative of the observer.

10.2.8.9 Ceiling classification

The ceiling is classified according to its nature and the method by which it is determined.

10.2.8.9.1

When the height of a layer aloft is designated as the ceiling, the ceiling classification shall be one of the following (the listed order also indicates priority when two or more of these classifications apply).

Classification:

  1. Measured: M
  2. Aircraft: A
  3. Balloon: B
  4. Estimated: E
10.2.8.9.2

When the vertical visibility, in a surface-based layer which completely obscures the sky, is designated as the ceiling, the ceiling classification shall be one of the following (the listed order also indicates priority).

Classification:

  1. Aircraft: A
  2. Precipitation: P
  3. Indefinite: W
10.2.8.9.3

To indicate the ceiling classification, prefix the appropriate abbreviation (without spacing) to the numerical value of the ceiling. Details regarding the requirements of the various classifications are given below.

10.2.8.9.4

Measured is the ceiling classification employed when:

  1. The height of the base of a layer aloft is determined by use of a ceiling projector or ceilometer, and the projector spot or ceilometer reaction is sharply defined.
  2. The height of the base of a layer aloft is determined from the known heights of unobscured portions of objects such as buildings, towers, etc., within 1 1/2 miles of the boundary of the field, if the observer believes that the height of the layer at the location of the tall object concerned is representative of the height of the layer at the station.
10.2.8.9.5

Aircraft is the ceiling classification employed when:

  1. The height of the base of a layer aloft or the vertical visibility in a surface-based layer is determined from information reported by the pilot of an aircraft and the height measurement was obtained by the pilot while over the geographical limits of the aerodrome itself, and the report is not more than 15 minutes old and the conditions reported by the pilot are considered by the observer to be representative of conditions at the time of the observation.
  2. A report, not more than 15 minutes old, is received from an aircraft which was not over the aerodrome at the time of the height measurements, but was within 1 1/2 mile of the boundary of the field, and the observer considers the conditions where the observation was made to be representative of conditions over the aerodrome.
10.2.8.9.6

Balloon is the ceiling classification employed when the height of the base of a layer aloft is determined by observation of a ceiling balloon, and the height of the base of the layer is computed from the assumed rate of ascent and the time interval between the release of the balloon and its entry into the base of the layer.

10.2.8.9.7

Indefinite is the ceiling classification used when, in a surface-based layer not composed of precipitation, the height of vertical visibility constitutes a ceiling and the classification "Aircraft" is not appropriate.

10.2.8.9.8

Precipitation is the ceiling classification used when, in a surface-based layer composed of precipitation, the height of vertical visibility constitutes a ceiling and the classification "Aircraft" is not appropriate.

Note: When appropriate, "Aircraft" (see 10.2.8.9.5) shall be the classification employed for the value of the vertical visibility into a surface-based layer which completely obscures the sky. When the classification "Aircraft" is not appropriate, either "Indefinite" or "Precipitation" shall be the classification regardless of the aids (e.g., balloons, ceiling projector etc.) which may have been used in estimating the vertical visibility.

10.2.8.9.9

Estimated is the classification employed when the height of the base of a layer aloft is determined by visual estimation or by means other than those that would allow one of the classifications "Measured," "Aircraft" or "Balloon" to be used.

10.2.8.10 Variable ceiling

When the ceiling is 900 m or less and is observed to be "variable," (i.e., rising and falling from a mean value by 1/4 or more of the mean value (see 1.6.5)), the range of variation shall be indicated in Remarks (41).

Example of entries in 2322 form
Description of image

This is an example of entries on the 2322 form when the ceiling is 900 m or less and is observed to be “variable”. Example data is inputted into the sky condition, obscuring phenomena and remarks columns.

10.2.8.11 Additional instructions

10.2.8.11.1

In the hourly observation, the ceiling may be recognized as the height ascribed to the lowest layer of cloud or obscuring phenomenon that is reported as broken, overcast or obscured, and not qualified by "thin" or "partially." The ceiling is also distinguished from other coded heights in the sky condition group by the letter which designates the ceiling classification and which immediately precedes the coded numerical value of the ceiling. The absence of a ceiling classification letter indicates "ceiling unlimited."

Note: In a METAR , ceiling classification letters are not used. In a METAR , the ceiling is the lowest height at which a broken or overcast condition exists or the vertical visibility when an obscured condition such as snow, smoke or fog exists, whichever is the lower.

10.2.8.11.2

The sky cover symbol X (obscured) shall be used in conjunction with the symbols FEW , SCT or BKN when a cloud, at a height less than the vertical visibility, assists in hiding the sky.

Example of entries in 2322 form (See long description below)
Description of image

This chart provides an example of entries when the sky cover symbol X (obscured) shall be used in conjunction with the symbols FEW, SCT or BKN when a cloud, at a height less than the vertical visibility, assists in hiding the sky. Data is entered under the columns total opacity, total amount, sky condition and obscuring phenomena.


View larger image

10.2.8.11.3

A height is not ascribed to sky-cover term CLR or -X (partially obscured).

10.2.8.11.4

Surface-based layers such as fog, blowing snow, etc., are reported by sky cover symbols X or -X as appropriate. Surface-based layers within sight but not at the point of observation shall be reported in Remarks (41).

Note: A surface-based layer which conceals less than 1/10 of the sky (summation opacity) shall be disregarded.

10.2.8.11.5 Examples of sky cover reports
Examples of Sky Cover Reports
Layers Opacity Amount Summation opacity Summation amount Sky condition (Col. 30) Clouds and/or obscuring phenomena type / opacity (Col. 40)
Fog, surface
SF , 300 m
SC , 1500 m
4
3
2
4
3
2
4
7
9
4
7
9
-X M10 BKN 50 BKN FG4 SF3 SC2
CF , 240 m
SC , 600 m
AC , 2250 m
2
4
4
2
4
4
2
6
10
2
6
10
8 FEW E20 BKN 75 OVC CF2 SC4 AC4
SF , 150 m
Snow, 450 m
3
7
3
7
3
10
3
10
5 FEW P15 X SF3 SN7
Fog, surface
Smoke 150 m
6
2
6
3
6
8
6
9
-X B5 BKN FG6 FU2
Smoke 240 m
ST , 360 m
4
4
6
4
4
8
6
10
8 -BKN M12 OVC FU4 ST4
Smoke, 90 m
SC , 1050 m
1
4
3
5
1
5
3
8
3 -FEW 35 -BKN FU1 SC4
Smoke, 90 m
SC , 1050 m
2
5
3
7
2
7
3
10
3 -FEW E35 OVC FU2 SC5
ST , 150 m
SC , 750 m
2
8
10
8
2
10
10
10
5 -OVC E25 OVC ST2 SC8
ST , 150 m
AS , 2550 m
2
3
10
3
2
5
10
10
5 -OVC 85 -OVC ST2 AS3
ST , 150 m
AS , 2100 m
9
1
10
1
9
10
10
10
M5 OVC 70 OVC ST9 AS1
CF , 150 m
SC , 750 m
1
5
1
5
1
6
1
6
5 FEW E25 BKN CF1 SC5

 

10.2.9 Column 31 - visibility

Enter the prevailing visibility (see 2.2) to the nearest reportable value (see 10.2.9.1). If the observed prevailing visibility is exactly half-way between two reportable values, use the "lower" value.

10.2.9.1 Reportable values of visibility

The following values (in statute miles) shall be used for reporting visibility:

  1. 0, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4 (increments of 1/8 mile);
  2. 1, 1 1/4, 1 1/2, 1 3/4, 2, 2 1/4, 2 1/2 (increments of 1/4 mile);
  3. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 (increments of 1 mile);
  4. 15+ (if suitable markers beyond 15 miles are lacking);
  5. 20, 25, 30, 35, etc., (increments of 5 miles) shall be used only if suitable visibility markers are available.

10.2.9.2 Variable visibility

If the prevailing visibility is observed to be variable, see 2.5, i.e., increasing and decreasing from a mean value by 1/4 or more of the mean value. Indicate the range of variation in Remarks.

Example:

Example of variable visibility entries in 2322 form (See long description below)
Description of image

This provides 2 examples on the 2322 form of Variable Visibility and how the range of variation shall be captured under Remarks.

10.2.9.3 For different directions

If the visibility in one or more directions is half or less, or double or more the prevailing visibility, details of the visibility in such directions shall be recorded in Remarks (41).

Example:

Example of different direction entries in 2322 form (See long description below)
Description of image

This provides 2 examples for Visibility in Different Directions varies and how the details in such shall be recorded under Remarks.

10.2.9.4 Additional instructions

When observing visibility from elevated positions, such as a control tower or roof, if the visibility differs by a reportable value from the prevailing visibility observed on the ground (at eye level), the visibility from the elevated position and the identification of the position shall be reported in Remarks.

Example:

Example of additional instruction entries in 2322 form (See long description below)
Description of image

This is an example for Additional Instructions entries under Remarks when observing visibility from elevated positions, such as a control tower or roof, if the visibility differs by a reportable value from the prevailing visibility observed on the ground. The visibility from the elevated position and the identification of the position shall be represented in the Remarks column.

10.2.9.4.1

With "blowing snow" conditions, the reporting of roof-top visibility is particularly important. Frequently, visibility is much better a short distance above ground level. Ground-level visibility alone in such circumstances does not give a full description of the visibility that would be experienced by the pilot of an aircraft.

10.2.9.4.2

With low-lying "fog" conditions, the observer should provide an estimate of the depth of the fog as well as the roof-top visibility.

Example:

Example of depth of fog entries in 2322 form (See long description below)
Description of image

This is an example for low-lying ‘fog’ conditions entered under Remarks.  With these conditions the observer should provide an estimate of the depth of the fog as well as the roof-top visibility.


View larger image

10.2.9.4.3

Directions in Remarks shall be recorded in a clockwise order from true north.

10.2.10 Column 32 - weather and obstructions to vision

10.2.10.1

Symbols for the conditions of weather and obstructions to vision which may be reported in Column 32 are listed below:

Table for Symbols for the conditions of weather and obstructions to vision which may be reported in Column 32
Weather and obstructions to vision Symbols
Tornadoes
Tornado +FC (TORNADO in Remarks)
Waterspout +FC (WATERSPOUT in Remarks)
Funnel cloud FC (FUNNEL CLOUD in Remarks)
Thunderstorms
Thunderstorm TS
Precipitation
Rain -RA , RA , +RA
Rain showers -SHRA , SHRA , +SHRA
Drizzle -DZ , DZ , +DZ
Freezing rain -FZRA , FZRA , +FZRA
Freezing drizzle -FZDZ , FZDZ , +FZDZ
Snow -SN , SN , +SN
Snow showers -SHSN , SHSN , +SHSN
Snow grains -SG , SG , +SG
Ice crystals IC
Ice pellets -PL, PL , +PL
Ice pellet showers -SHPL , SHPL , +SHPL
Hail (diameter of largest stone =5 mm) -SHGR , SHGR , +SHGR
Hail (diameter of largest stone <5 mm) -SHGS , SHGS , +SHGS
Snow pellets -SHGS , SHGS , +SHGS
Obstructions to vision (visibility < 6 mi.)
Fog (visibility <5/8 mi.) FG
Freezing Fog (visibility <5/8 mi., temp <0 to - 30 °C) FZFG
Mist (visibility 5/8 mi. to 6 mi.) BR
Haze HZ
Smoke FU
Blowing snow BLSN , +BLSN
Blowing sand BLSA , +BLSA
Blowing dust BLDU , +BLDU
Duststorm DS , +DS
Sandstorm SS , +SS
Additional phenomena (visibility > 6 mi.)
Dust haze DU
Shallow fog patches MIFG
Fog patches BCFG
Fog covering part of aerodrome PRFG
Drifting dust DRDU
Drifting sand DRSA
Drifting snow DRSN
Dust/sand whirls PO
Volcanic ash VA
In the vicinity phenomena
Showers in the vicinity VCSH
Duststorm in the vicinity VCDS
Sandstorm in the vicinity VCSS
Fog in the vicinity VCFG
Dust/sand whirls in the vicinity VCPO
Blowing dust in the vicinity VCBLDU
Blowing sand in the vicinity VCBLSA
Blowing snow in the vicinity VCBLSN
Volcanic ash in the vicinity VCVA

10.2.10.2 Intensity of precipitation

The intensity of precipitation shall be indicated by the symbol "+" to indicate "heavy," the symbol "-" to indicate "light" and the absence of such a symbol indicates "moderate" intensity. An exception to the foregoing is ice crystals, to which no intensity is ascribed. The criteria for determining the intensity of precipitation are given in Part A, Chapter 3, "Atmospheric phenomena."

10.2.10.3

Two or more entries for a single observation shall be made in the following order:

  1. Tornado, waterspout, funnel cloud
  2. Thunderstorm
  3. Liquid precipitation, in order of decreasing intensity
  4. Freezing precipitation, in order of decreasing intensity
  5. Frozen precipitation, in order of decreasing intensity
  6. Obstructions to vision, in order of decreasing predominance
  7. Additional phenomena and vicinity phenomena

10.2.10.4

Record in Column 32 only those phenomena which are occurring at the station, in the vicinity of the station, at the time of observation with the following exceptions:

  1. Tornado, waterspout or funnel cloud shall be recorded if within sight at the time of observation.
  2. Thunderstorm shall be recorded when:
    1. Thunder is heard within the past 15 minutes; or
    2. Overhead lightning is observed within the past 15 minutes and the local noise level is such as might prevent hearing thunder. In this case, hail may also be an indicator of a thunderstorm in progress.

Note: Additional phenomena and in the vicinity phenomena shall be recorded in Column 32 and if not enough space in Column 41 (Remarks).

VC indicates significant weather phenomena observed in the vicinity of the aerodrome (the point of observation). "In the vicinity" means within 8 km (5 miles) but not within the perimeter of the aerodrome. VC codes shall be reported in hourly reports and SPECIs. VC codes shall replace the corresponding remark i.e. VCSH would be used to replace the remark SN SH 3 MI E.

10.2.10.5

Precipitation of an intermittent or showery character, which has been active at the station within the preceding 15 minutes, is not occurring at the time of observation, but is expected to begin again soon, shall be reported by remarks in Column 41.

Example:

Example of precipitation entries in 2322 form (See long description below)
Description of image

This provides 2 examples of entries under Remarks for precipitation of an intermittent or showery character, which has been active at the station within the preceding 15 minutes, is not occurring at the time of observation, but is expected to begin again soon. This shall be represented by remarks in column 41.


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When intermittent precipitation is occurring at the time of observation, the remark is of the form "-RA INTMT".

10.2.10.6

Obstructions to vision (see 10.2.10.1) shall be recorded in Column 32 only when the prevailing visibility is 6 miles or less.

Note: Precipitation of sufficient intensity may account for a considerable reduction in visibility without the presence of any obstruction to vision. However, when rain is occurring with visibilities less than 2 miles some "obstruction to vision" should be reported with the rain, unless there is evidence that only the rain is restricting visibility. Light or moderate rainfall (e.g., -RA or SHRA), without an obstruction to vision, will not be sufficient to reduce visibility to less than 2 miles.

10.2.10.7

When precipitation, low cloud or an obstruction to vision, within sight but not at the station, restricts the prevailing visibility to 6 miles or less, an entry shall be made in Column 32. Explanatory Remarks clarifying the precipitation or obstruction to vision could be entered in Column 41.

Example:

Example of obstruction to vision entries in 2322 form (See long description below)
Description of image

This provides 3 examples of entries under column 32 - Weather and Obstructions to Vision, when precipitation, low cloud or an obstruction to vision within sight but not at the station restricts the prevailing visibility to 6 miles or less.


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Note: When the prevailing visibility reported in Column 31 is 6 miles or less, an entry is required in either Column 32 or Remarks to explain the reduced visibility.

10.2.10.8

Ice Crystals (IC) are a common form of precipitation at very low temperatures. This type of precipitation may continue for several days without interruption and frequently falls from a cloudless sky. The restriction to vision may or may not be severe.

To meet Canadian standards, when ice crystals (IC) are observed it shall be reported in the METAR / SPECI with any visibility.

10.2.10.9

Snow and fog should not be reported together unless there is very good evidence that fog exists. The occurrence of hoar frost or rime constitutes evidence to support a report of fog.

10.2.10.10

Drifting snow, sand or dust shall not be reported in the same observation as blowing conditions of the same phenomena; by definition one excludes the other. For example, drifting snow shall not be reported with blowing snow.

10.2.10.11

Liquid precipitation and freezing precipitation shall not be reported in the same observation. By definition one excludes the other.

10.2.11 Column 33 - sea level pressure

Enter the atmospheric pressure, reduced to sea level in hectopascal and tenths with the initial 9 or 10 and the decimal point omitted, e.g., record 1013.2 hPa as 132; record 990.6 hPa as 906.

10.2.11.1

The digital barometer shall be used for determining atmospheric pressure. A reduction to sea level shall be computed at the time of each main and intermediate synoptic report, i.e., at 0000, 0300, 0600, 0900, 1200, 1500, 1800 and 2100 UTC ; at sites equipped with data entry screen, it will be obtained from the data entry screen.

Note: If the mean sea level pressure is manually calculated, enter the mean sea level reduction in brackets in Column 41 "Remarks" each time that a new mean sea level reduction is calculated and at the time of the first observation for use until the next correction has been determined, see 4.2.3.3.

10.2.12 Column 34 - dry-bulb temperature

Enter the corrected dry-bulb temperature in degrees and tenths Celsius.

10.2.12.1

Entries which are below zero Celsius shall be prefixed with a minus (-) sign.

Example:

Example of entries below zero Celsius on the 63-2322 Form (See long description below)
Description of image

This provides 2 examples on how to record Dry Bulb temperatures below zero Celsius.

10.2.13 Column 35 - dewpoint temperature

Enter the corrected dewpoint temperature in degrees and tenths Celsius.

10.2.13.1

Entries which are below zero Celsius shall be prefixed with a minus (-) sign.

Example:

Example of entires below zero Celsius on the 63-2322 Form (See long description below)
Description of image

This provides examples on how to record Dew-Point Temperatures below zero Celsius.

Note (1): When the MSC dewcel is unserviceable for any reason, other than low temperature limit, the psychrometric data shall be calculated from dry-bulb and wet-bulb readings obtained from one of the following: motor ventilated psychrometer, sling psychrometer or simple psychrometer.

Note (2): In no case shall the entry in Column 35 be higher (warmer) than that of Column 34. When such a value is obtained from the dewcel or the psychrometric tables, the value of the dewpoint shall be reduced to correspond to the dry-bulb temperature.

Note (3): Enter "M " in Column 35 whenever:

  • The corrected temperature from the dry-bulb thermometer is colder than -37°C;
  • The corrected temperature from the dry-bulb thermistor is colder than -45°C; or
  • The dewcel reading is off the scale.

10.2.14 Column 36 - wind direction

Enter the two-minute mean direction from which the surface wind is blowing to the nearest ten degrees (00-36).

Example: 130 degrees shall be reported as 13; 060 degrees shall be reported as 06. When the wind is “calm, enter 00. Directions from wind equipment which can be read only in compass points shall be converted to tens of degrees as follows:

Conversion table of compass points directions to tens of degrees
Compass point Tens of degrees
N1 36
NNE 02
NE1 05
ENE 07
E1 09
ESE 11
SE1 14
SSE 16
S1 18
SSW 20
SW1 23
WSW 25
W1 27
WNW 29
NW1 32
NNW 34

Return to footnote1 Note: Estimated wind direction shall be to eight points of the compass and converted to tens of degrees using the above table.

10.2.15 Column 37 - wind speed

Enter the two-minute mean wind speed in knots. If either the speed or the direction is estimated, enter the letter "E" immediately after the wind speed. Estimates do not apply to conditions of very low wind speeds less than 2 kts. These shall be reported as "calm", see 7.1.2. Wind speed shall always be reported as a two or three-digit group. Enter 00 for calm. For speeds of 2-9 kts, enter 02, 03, etc. For speeds of 100 kts or over, enter 100, 101, 102, etc.

Note: "Calm" is reported for mean wind speeds of less than 2 kts.

Image of Form 62-2322 with example entries (See long description below)
Description of image

This is an example of how to record wind speed of 109 knots (also providing direction).


View larger image

Note (1): When both synoptic and hourly observations are recorded at the same hour, the two-minute mean wind data shall be entered in columns 36 and 37 of Form 63-2322. At these times, an additional observation of the ten-minute mean wind is required for synoptic coding. This observation shall be entered in the Observer's Notebook.

Note (2): When suitable instruments are lacking, or when the instruments are not in operating condition, the wind direction and speed shall be estimated, see 7.4.

10.2.16 Column 38 - wind character

10.2.16.1 Gusts

Enter the letter “G” if gusts (see 7.1.3.1.1) have been observed in the 10-minute period ending at the time of the observation. The symbol is followed by the numerical value of the peak speed of the gust.

10.2.16.1.1

Enter the highest of the peak speeds observed or recorded during the 10 minutes ending at the time of the observation.

10.2.16.1.2

If the station is not equipped with instruments that indicate wind speed fluctuations but the observer is confident that the gust criteria have been met, record the symbol G for the character. Do not enter a peak speed. Do not estimate the peak speed of a gust.

Example:

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides 3 examples of how to record gusts, requiring information for direction, speed and character.

10.2.16.2 Squalls

Enter the symbol “Q” when a squall (see 7.1.3.2) has been observed during the 10-minute period ending at the time of the observation. The symbol is followed by the numerical value of the peak speed of the squall.

10.2.16.2.1

The squall speed entered is the highest one-minute speed observed or recorded during the squall period. Squall speeds shall be obtained from recording wind devices.

10.2.16.2.2

If the station is not equipped with recording devices, but the observer is confident that the criteria for squalls are being met, then enter the symbol Q only. Do not enter a squall speed. Do not estimate a squall speed. (The situations most likely to produce squalls are thunderstorms and rapidly moving cold fronts.)

Example:

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides 3 examples of how to record Squalls, requiring information for direction, speed and character.

10.2.17 Column 39 - altimeter setting

Enter the altimeter setting (QNH) in inches, omitting the tens digit and the decimal point.

Example: An altimeter entry of 992 indicates an altimeter setting of 29.92 inches (see table in 4.3.2).

Note (1): To prevent any gross errors, always compare the altimeter setting which has just been calculated with the one previously reported. The difference between these two altimeter settings should be consistent with the change in the computed station pressure, and as indicated by the barograph for the same period.

Example: If the barograph indicates an increase of 1.0 hPa during the last hour, the altimeter setting should increase by approximately 0.03 inches.

Note (2): To assist in checking the 0700 UTC altimeter setting, a space is provided at the top of Column 39 where the previous altimeter setting (0600 UTC) should be recorded.

10.2.18 Column 40 - clouds and/or obscuring phenomena

Enter the type and opacity of each layer for which a sky-cover symbol is given in Column 30.

10.2.18.1

When a layer consists of two or more types, e.g., SC and CU , the predominating type by amount shall be recorded. If a cloud layer consists of any amount of TCU or CB, the TCU or CB shall be reported as the predominant type. However when an individual layer of cloud is composed of Cumulonimbus (CB) and Towering Cumulus (TCU) with a common cloud base, the type shall be reported as Cumulonimbus only. Clouds and obscuring phenomena abbreviations are listed below:

Table for clouds and obscuring phenomena abbreviations
Clouds Abbreviations
Altocumulus AC
Altocumulus Castellanus ACC
Altostratus AS
Cirrocumulus CC
Cirrostratus CS
Cirrus CI
Cumulonimbus CB
Cumulus CU
Cumulus Fractus CF
Stratus Fractus SF
Towering Cumulus TCU
Nimbostratus NS
Stratocumulus SC
Stratus ST


Table for clouds and obscuring phenomena abbreviations
Obscuring Phenomena Abbreviations
Rain (any form including SHRA and FZRA) RA
Hail SHGR
Ice Pellets (including Ice Pellet Showers) PL
Drizzle (including Freezing Drizzle) DZ
Ice Crystals IC
Snow (Snow Showers, Snow Pellets and Snow Grains) SN
Blowing Snow BLSN
Fog (any form) FG
Dust, Blowing Dust BLDU
Dust Storm DS
Haze HZ
Sand, Blowing Sand BLSA
Sandstorm SS
Smoke FU
Volcanic Ash VA

Note: The cloud type described in the International Cloud Atlas as "Cumulus Congestus" is listed above as "Towering Cumulus" (TCU).

10.2.18.2

Opacity shall be expressed in tenths of the whole sky. If the opacity of a layer aloft (excluding traces of cloud) is zero, enter only the type, e.g., CI. If the opacity is 1/10 or the layer is a trace, the opacity in Column 40 is entered as "1".

10.2.18.3

Examples of type and opacity entries in Column 40 (note that obscuring phenomena which constitute layers are also included):

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of Cloud type and opacity entries in Column 40 - Clouds and/or Obscuring Phenomena and entries for sky condition.


View larger image

Note: The third entry of this report indicates SC cloud 9/10 opacity and 9/10 amount and AC cloud with 0 opacity and 1/10 amount.

10.2.19 Column 41 - Remarks

Meteorological information of importance to aviation and other users which has not been given previously in the report shall be recorded under Remarks. Weather symbols and abbreviations authorized in MANAB (Manual of Word Abbreviations) shall be used to conserve space as much as possible. However, plain language, English words shall be used as necessary to amplify or clarify the information.

Information not of direct importance to aviation and not intended for transmission is recorded in Remarks and it shall be enclosed in brackets, e.g., the sea level reduction. Hourly station pressure values shall be recorded in the partial column to the right of Remarks wherever a regional or local need exists.

Priority - recording

The following priority shall be observed when recording Remarks in the hourly observation:

  1. General weather Remarks (see 10.2.19.1 to 10.2.19.8)
  2. Snowfall (see 10.2.19.9)
  3. Rainfall (see 10.2.19.10)
  4. Hail size (see 10.2.19.12)
  5. Runway Visual Range (RVR) (see 10.2.19.13)

Priority - transmitting

When transmitting Remarks in the hourly observation, the above priority shall be observed.

Note (1): The observer is encouraged to use the Remarks portion of the hourly observation. Entries in Remarks are by no means restricted to the examples over the next few pages.

Note (2): Late weather observation shall be recorded first in Column 41 as a general weather remark (See 10.2.19.14.1

10.2.19.1 Sky cover (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Sky Cover (Remarks) (as well as entries for sky condition and obscuring phenomena).


View larger image

"CONTRAILS" shall be used when the CM or CH cloud consists in whole or in part of persistent (15 minutes or more) condensation trails. Rapidly dissipating condensation trails shall not be reported.

10.2.19.2 Ceiling (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Ceiling (Remarks) (as well as entries for sky condition and obscuring phenomena).

10.2.19.3 Visibility (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Visibility (Remarks) (and entries into weather / obstructions to vision).

10.2.19.4 Weather (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Weather (Remarks) (with entries also under sky condition and visibility).


View larger image

TORNADO SW MOVG E: If a tornado, water spout or funnel cloud is reported by the public, the following shall be indicated:

  1. The location with respect to the station, city or town;
  2. The direction towards which it is moving; and
  3. The time the phenomenon was observed.

INTMT -RA : Intermittent rain was not occurring at the time but was active within 15 minutes preceding the time of the observation.

OCNL DIST LTGCC SW: When lightning is observed, indicate frequency, type (LTGCG , LTGIC and LTGCC) and direction from station.

OCNL -SHRA : Rain showers were not occurring at the time but were active within 15 minutes preceding the time of the observation.

FROIN : is used to report frost on the ice accretion indicator.

10.2.19.5 Obstruction to vision (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Obstruction to Vision (Remarks) (with entries under sky condition, visibility, weather and obstructions to vision).

10.2.19.6 Wind (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Wind (Remarks) (with entries under direction, speed and character).


View larger image

10.2.19.6.1

If winds are estimated due to ice accretion, the following remark shall be included in the report: WND ESTD DUE ICE ACCRETION.

10.2.19.6.2

If winds are estimated for reasons other than ice accretion, the following remark shall be included in the report: WND ESTD.

10.2.19.6.3 Wind direction variation

If, during the 10-minute period preceding the observation, the total variation in wind direction is 60° or more and less than 180° and the mean wind speed is 3 kts or greater, the observed two extreme directions between which the wind has varied shall be given for DnDnDnVDxDxDxin clockwise order. Otherwise this group shall not be included. Enter wind direction variation in the specific field or enter in Remarks in the following format:

DnDnDn - Extreme counter clockwise wind direction

V - Variable

DxDxDx - Extreme clockwise wind direction

Example: 240V350

10.2.19.6.4 Low-level wind shear

Wind shear information on the existence of wind shear 1500 feet AGL and below along the take-off path or approach path of runway significant to aircraft operations shall be reported in Column 41 (Remarks) whenever available and local circumstances so warrant. The information will be reported in the following format:

  • When wind shear is reported on take-off or landing on one runway 1500 feet AGL and below it will be reported as: WS RWY DRDR (Official Runway Designation)
    or
  • When wind shear is affecting all runways 1500 feet AGL and below, it will be reported as: WS ALL RWY

10.2.19.7 Pressure change (Remarks)

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Pressure Change (Remarks).


View larger image

PRESRR  is used when the barograph trace indicates that the station pressure is rising at the rate of 2.0 hPa or more per hour.

PRESFR  is used when the barograph trace indicates that the station pressure is falling at the rate of 2.0 hPa or more per hour.

Note: If the barograph trace shows a steady increase of 0.5 hPa during the last 15 minutes, the rate of increase would be 2.0 hPa per hour and the remark PRESRR would be appropriate.

10.2.19.8 Clouds (Remarks)

10.2.19.8.1

If clouds which indicate unstable conditions (CB, TCU or ACC) are observed and not reported in Column 40, they shall be reported in Remarks.

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Cloud (Remarks). Data is entered for sky condition, clouds, and remarks.


View larger image

10.2.19.8.2

Orographic clouds, also known as "Mountain" or "Standing Wave Clouds" shall be reported in Remarks whether or not the clouds are predominant. These clouds sometimes indicate severe turbulence aloft and are normally seen in areas up to 350 km to the leeward of mountains or hills and may occur for a period of five or six hours or longer. Throughout the period during which orographic clouds are observed, Remarks shall be used to indicate their presence. Typical Remarks are:

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples of entries for Orographic clouds, with data under obscuring phenomena and remarks.


View larger image

Note: ACSL indicates Standing Lenticular Altocumulus.

10.2.19.8.3

Cloud direction may be given in Remarks if the observer considers the information significant. Typical remark is:

Image of Form 62-2322 with example entries (See long description below)
Description of image

This is an example of an entry for cloud direction if the observer considers the information significant, with data under obscuring phenomena and remarks.

10.2.19.9 Snowfall (Remarks)

10.2.19.9.1

The increasing depth of newly-fallen snow, since the time of the last main synoptic report, shall be reported in the Remarks section of an hourly report by means of a /Sss/ group. The letter "S" identifies the precipitation as snow and "ss" the units as whole centimetres.

10.2.19.9.2

The accumulating depth of newly-fallen snow, since the last main synoptic report, is normally obtained by ruler and rounded-off to whole centimetres.

Note: If all the snow melts as it hits the ground, /Sss/ would not be reported.

10.2.19.9.3

/Sss/ shall be reported only at the hours when the accumulated (rounded) value increases to equal or exceed 1 cm, or exceeds the previously reported value by 1 cm or more.

Example:

Image of Form 62-2322 with example entries (See long description below)
Description of image

This provides examples how Snowfall amounts shall be entered under Remarks. The appropriate data is also entered under hour, sky condition, visibility, weather and obstructions to vision and obscuring phenomena.


View larger image

Note: Codes for phenomena are entered in Column 32 in the appropriate order. If there is not sufficient room in Column 32, the overflow can be entered in Column 41, "Remarks."

10.2.19.10 Rainfall (Remarks)

10.2.19.10.1

Some stations, selected by their Regional Headquarters, will report the accumulated rainfall, since the time of the last main synoptic report, in the Remarks section of the hourly observation by means of a /Rrr/ group. The letter "R" identifies the precipitation as rain and "rr" the units in whole millimetres.

10.2.19.10.2

Rrr/ is the accumulative rainfall, rounded off to the nearest whole millimetre. The measurement may be obtained from a recording rain gauge, the standard type-B rain gauge or the AWOS Fischer and Porter precipitation gauge.

10.2.19.10.3

The /Rrr/ group shall be recorded and transmitted only at the hours when the rainfall accumulated since the time of the last main synoptic report equals or exceeds 10 mm (rounded), or exceeds the previously reported value by 10 mm (rounded) or more.

Example:

Table for calculating hourly rainfall entries
Time (UTC) Accumulated rainfall (mm) Recorded rainfall (col. 41)
0700 3.2  
0800 9.8 /R10/
0900 20.2 /R20/
1000 29.7 /R30/
1100 39.1  
1200 43.4 /R43/
1300 10.1 /R10/

10.2.19.11 Snowfall (or rainfall) reporting procedures for part-time stations

10.2.19.11.1

Part-time stations are defined as operating daily but fewer than 24 hours.

10.2.19.11.2

When the station reopens, the first observation will indicate the reportable snowfall (or rainfall) amount, using the format /Sss AFT HH/ (or /Rrr AFT HH/), where HH is the hour (UTC) of the main synoptic at or prior to the time of closing.

10.2.19.11.3

If the closed period includes a main synoptic hour, and if the reopening time is at a non-synoptic hour, the second and subsequent snow (or rain) reports will take the form /Ss1s1 AFT H1H1UTC/, where the flag indicates that H1H1UTC is the time the station reopened and s1s1 is the snowfall (or rainfall) amount since the station reopened.

Note: For rainfall, Ss1s1is replaced by Rr1r1

10.2.19.11.4

The following diagram shows three closing and opening situations. The reporting procedures for coding and reporting each situation is described below the diagrams.

Diagram showing three closing and opening situations (See long description below)
Description of image

This diagram illustrates three examples of closing and opening situations for a station. In example 1, the station is open at 00z until 04z. The station is closed from 04z until 14z, and open again from 14z to 01z. In example 2, the station is open at 00z until 08z. The station is closed from 08z until 01z. In example 3, the station is closed at 00z until 09z. The station is open from 09z until 01z.


View larger image

Example (1): Opening time 1400 UTC (opening can be from 13 UTC to 17 UTC)

First report, use the format: /Sss AFT 00UTC/
Subsequent reports, up to and including 18UTC, use format: /Ss1s1 AFT 14UTC/

Example (2): Opening time 0000 UTC

First report, use the format: /Sss AFT 06UTC/
Subsequent reports, use conventional format: /Sss/

Example (3): Opening time 0900 UTC (opening can be from 07 UTC to 11 UTC)

First report, use the format: /Sss AFT 00UTC/
Subsequent reports, up to and including 12 UTC, use format: /Ss1s1 AFT 09UTC/

Note: For rainfall, Sss is replaced by Rrr.

10.2.19.12 Hail size (Remarks)

10.2.19.12.1

When hail is observed at the station, the average size of the hail shall be estimated in whole millimetres, recorded in Column 41, and transmitted in Remarks in the following format: HAIL DIAM nn MM

Where "nn" is the average diameter in whole millimetres, e.g., HAIL DIAM 09 MM.

10.2.19.13 Runway Visual Range (RVR)

Where RVR data is displayed, it shall be included in hourly and SPECI observations. RVR shall be reported for the active or most-aligned into-the-wind runway(s) when the prevailing visibility is 1 SM or less and/or the RVR value for the designated runway(s) is 6,000 feet or less. Stations with the capability to display values for multiple RVR's may record and transmit a maximum of four RVR values and may include RVR data for runway(s) other than the active or most-aligned into-the-wind. All RVR values transmitted shall be representative of the touchdown zone of the active landing runway(s).

10.2.19.13.1

RVR is recorded and transmitted using the following format:

RDRDR/VRVRVRVRi or RDRDR/VRVRVRVRVVRVRVRVRi 

10.2.19.13.2 Group RDRDR/VRVRVRVR

R: Indicator.

DRDR: The designator of each runway for which runway visual range is reported. Parallel runways should be distinguished by appending to DRDR letters L, C or R indicating the left, central or right parallel runway, respectively. A suitable combination of these letters is used for up to, and including, five parallel runways (i.e. LL, L, C, R, RR). The letter(s) shall be appended to DRDR as necessary in accordance with the standard practice for runway designation.

VRVRVRVR: Mean value of runway visual range over the 10-minute period immediately preceding the observation. However, when the 10-minute period includes a marked discontinuity in the RVR (for example, sudden advection of fog, rapid onset or cessation of an obscuring snow shower), only the data after the discontinuity shall be used for obtaining mean RVR values and variations thereof, hence the time interval in these circumstances shall be correspondingly reduced. FT shall be appended to the measurement to indicate that the measurement is in feet.

i: If the runway visual range values during the 10-minute period preceding the observation shows a distinct upward or downward tendency such that the mean during the first five minutes varies by 300 feet or more from the mean during the second five minutes of the period, this shall be indicated by i = U for upward and i = D for downward tendency of runway visual range values. When no distinct change in runway visual range is observed, i = N shall be used. When it is not possible to determine the tendency, i shall be omitted.

10.2.19.13.3 RDRDR/VRVRVRVRVVRVRVRVRi - significant variation of runway range

When the RVR at a runway varies significantly and when during the 10-minute period preceding the nominal observation time, the one-minute mean extreme values assessed vary from the mean value by more than 150 feet or more than 20% of the mean value, whichever is greater, the one-minute mean minimum and the one-minute mean maximum values shall be given in that order in the form RDRDR/VRVRVRVRVVRVRVRVRi instead of the 10-minute mean. The tendency shall also be included.

10.2.19.13.4

When actual RVR values are outside the measuring range of the observing system in use, the following procedure shall apply:

  1. When the RVR is greater than the maximum value which can be assessed with the system in use, P shall be appended to the group VRVRVRVR: e.g. P6000.
  2. When the RVR is below the minimum value which can assessed with the system in use, M shall be appended to the group VRVRVRVR: e.g. M0600.
10.2.19.13.5

Sites that are using RVR data based on a 10-minute mean shall enter the RVR data in the specified field of the input screen and record in Column 41.

10.2.19.13.6

Sites that are using the Remarks section to transmit RVR shall use only one value of RVR tendency and variations by this method shall not be reported in Remarks.

Example: RVR RWY 06R 1600FT

10.2.19.14 Late weather observations

In order that users of weather observations may have confidence in the observations and use them safely, it cannot be overstressed that hourly observations must be accurate and adhere to the schedules specified in Chapter 9, "Observing and reporting priorities." An occasion may arise, beyond the control of the observer, which would necessitate taking the observation either early or late. Since in an hourly observation the barometer is read exactly on the hour, the following procedures shall be used if a departure from the scheduled time is unavoidable.

10.2.19.14.1

The number of minutes before or after the hour that the barometer is read shall be recorded in Column 41 as the first of "General Weather Remarks" (see 10.2.19). The format of the remark shall be, "OBS TAKEN ±tt", where "+tt" indicates that the barometer was read (or the observation was made) "tt" minutes after the hour, and "-tt" indicates that the barometer was read (or the observation was made) "tt" minutes before the hour recorded in Column 29.

Example:

OBS TAKEN +18: the barometer reading was taken 18 minutes after the hour recorded in Column 29.

OBS TAKEN -12: the observation was taken 12 minutes before the hour.

10.2.19.15 Observational program status

In order that users of weather observations can determine if a station is staffed or when the next observation will be, Remarks indicating the status of operation are required.

10.2.19.15.1

At sites with less than a 24-hour observing program and observations not supplemented with an auto station, enter in the Remarks section for the last observation of the day, for example "LAST OBS/NEXT 241500 UTC".

10.2.19.15.2

At sites with a 24-hour program and a staff/machine mix for observations, enter in the Remarks section for the last staffed observation of the day, for example "LAST STFD OBS/NEXT 241500 UTC".

10.2.19.16 Station pressure

Enter the last three digits of the station pressure (hectopascal and tenths in the column labeled Stn. Pres.).

10.2.20 Column 42 - tendency

Enter a tendency code group at the main and intermediate synoptic hours (0000, 0300, 0600, 0900, 1200, 1500, 1800, 2100 UTC). The tendency shall take the same form as in the synoptic code "appp" where "a" is the code figure for the tendency characteristic (see 4.4.2.2) and "ppp" is the amount of pressure change in hectopascals and tenths.

Example:

Table for entering tendency group
Amount of change (hPa) Code ppp
0.0 000
0.3 003
1.1 011
10.2 102

10.2.21 Column 42a - additional data group

This group need not be recorded as the input screen has fields for total amount, total opacity and temperatures in degrees and tenths.

10.2.22 Column 43 - observer

The initials of the observer shall be printed legibly for each observation.

10.3 Types of observations

10.3.1

Observations are divided into two main types, i.e. "hourly" and "synoptic." Synoptic observations are discussed in Part C, “Synoptic observations.” Observations are further subdivided and classified as "hourly", "SPECI ", and "check". When two or more types of observation coincide, all elements observed for each type shall be included in the observation.

10.3.2 Hourly observations

Hourly observations are the observations taken to meet scheduled transmission times. The data listed below shall be included in the transmitted hourly observation unless otherwise authorized:

  • Sky condition
  • Visibility
  • Weather and obstruction to vision
  • Sea level pressure
  • Temperature
  • Dewpoint
  • Wind
  • Altimeter setting
  • Clouds
  • Remarks (if required)
  • Runway Visual Range (RVR) (where available)
  • Tendency

Note: The tendency shall be included at 0000, 0300, 0600, 0900, 1200, 1500, 1800 and 2100 UTC.

10.3.3 Hourly observations

Even when an hourly observation reveals that one or more of the criteria specified as requirements for SPECI observations has occurred, (see 10.3.5), the observation shall be designated as an Hourly observation. If the criteria for a SPECI observation have been met during the period H-5 to H, the observer is not required to transmit a SPECI observation before the hour.

Note: Threatening, severe weather (see “Priority of duties” in Introduction) shall require a SPECI observation with least possible delay.

10.3.4 SPECI

An observation shall be taken promptly to report changes which occur between scheduled transmission times. A SPECI observation shall include the following:

  • Sky condition
  • Visibility
  • Weather and obstruction to vision
  • Sea level pressure
  • Temperature
  • Dew point
  • Wind
  • Altimeter setting
  • Clouds
  • Remarks (if required)
  • Runway Visual Range (RVR) (where available)

10.3.5 Criteria for taking SPECI

A SPECI observation shall be taken whenever one or more of the elements listed, see 10.3.5.1 to 10.3.5.9, have changed in the amount specified. The amount of change is with reference to the preceding hourly or SPECI observation.

10.3.5.1 Ceiling

Ceiling decreases to less than or if below, increases to equal or exceed the following coded values of height, see 10.2.8.6.

  • 15
  • 10
  • 5
  • 41
  • 3
  • 21
  • 11
  • The additional limits as specified in Appendix V , entitled "IFR approach and alternate limits."

Return to footnote1 Note: Criteria are applicable only at aerodromes with precision approach equipment (i.e. ILS, MLS, GCA) and only down to and including the lowest published minima for these aerodromes.

10.3.5.2 Sky condition

A layer aloft is observed below:

  1. 300 m (coded height 10) and no layer aloft were reported below this height in the report immediately previous.
  2. The highest minimum for IFR straight-in landing or take-off, and no layer was reported below this height in the report immediately previous.

10.3.5.3 Visibility

Prevailing visibility decreases to less than or, if below, increases to equal or exceed:

  • 3 miles
  • 1 1/2 miles
  • 1 mile
  • 3/4 mile1
  • 1/2 mile
  • 1/4 mile1
  • The additional limit as specified in Appendix V , entitled "IFR approach and alternate limits."

1Note: Criteria marked with (1) are applicable only at aerodromes with precision approach equipment (i.e. ILS, MLS, GCA) and only down to and including the lowest published minima for these aerodromes.

Note(2): Under rapidly varying conditions of low ceiling and/or visibility, observers should, when possible, apply the provisions for the reporting of variation, see 10.2.8.10 and 10.2.9.2.

10.3.5.4 Tornado, waterspout or funnel cloud

  • Is observed
  • Disappears from sight
  • Is reported by the public (from reliable sources) to have occurred within the preceding six hours

10.3.5.5 Thunderstorm

  • Begins
  • Ends (SPECI observation shall be made when 15 minutes have elapsed without the occurrence of thunderstorm activity [see 3.3.1])

Example: (See 10.4.2.3, "Three periods of thunder and the necessary entries in columns 2, 3 and 4") SPECI would be required at 1210 for the beginning of the TS. SPECI at 1240 for ending the TS at 15 minutes past 1225. At 1250 another SPECI to begin another TS. At 1300, hourly observation. At 1345 another SPECI to end the TS.

10.3.5.6 Precipitation

When any of the following begin, end or change intensity:

  • Freezing rain
  • Freezing drizzle
  • Ice pellets (showery and non-showery)
  • Rain
  • Rain showers
  • Drizzle
  • Snow
  • Snow showers
  • Snow grains
  • Hail
  • Snow pellets
  • Ice crystals begin or end

SPECI shall be taken as required to report the beginning and ending of each individual type of precipitation, regardless of simultaneous occurrences of other types. A leeway of up to 15 minutes is allowed after the ending of precipitation before a SPECI is mandatory.

Changes in character of precipitation do not require a SPECI if the break in precipitation does not exceed 15 minutes and there is no change to the intensity of the precipitation.

Example:
-RA begins or -RA ends: SPECI is required
-RA changes to RA : SPECI is required
-RA changes to SHRA : SPECI is required
-RA changes to -SHRA : SPECI is not required
-RA changes to -RA INMT: SPECI is not required

10.3.5.7 Obstruction to vision

SPECI shall be taken to report the beginning or ending of freezing fog.

10.3.5.8 Temperature

  • The rounded temperature increases by 5°C or more from the previous reported value and the previous reported value was 20°C or higher.
  • The temperature decreases to a reported value of 2°C or lower.

Note: At sites designated by NAV CANADA as listed in Appendix II, entitled “Stations where SPECI reports are required for temperature changes.”

10.3.5.9 Wind

  • Speed (two-minute mean) increases suddenly to at least double the previously reported value and exceeds 30 kts.
  • Direction changes sufficiently to fulfill criteria required for a "Wind Shift," (see 7.1.4.1).

10.3.5.10 Volcanic eruption

The occurrence of a volcanic eruption shall be reported by a SPECI observation when observed. The following data shall be included in Remarks when known:

  • Name of the volcano.
  • Direction (16 points, true, of the compass) and approximate distance (statute miles) of the volcano.
  • Date/time (UTC) of eruption.
  • Height and direction of movement of ash cloud.
  • Other pertinent data.

Example of Remarks: MT ST HELEN VOLCANO 60 MI WNW ERUPTED 091025 ASH CLOUD TO 300 MOVG RPDLY SE

Post eruption volcanic ash clouds should be included in Remarks of hourly and SPECI observations as long as significant. Volcanic ash may be reported as smoke, haze or dust in column 40. Dust is normally reserved for cases in which a deposit is being made.

10.3.5.11 Observer's initiative

The criteria specified in the preceding paragraphs shall be regarded as the minimum requirements for taking SPECI observations. In addition, any weather condition that in the opinion of the observer, is important for the safety and efficiency of aircraft operations or otherwise significant, shall be reported by a SPECI observation.

10.3.5.12 Graphic reference guide for reporting a SPECI

Appendix I - Graphic reference guide may be used to assist in the identification of criteria for the issuance of special (SPECI) weather observations. Note that temperature criteria are only to be applied at sites specified by NAV CANADA.

10.3.6 Check observations

Check observations are taken during the time between hourly observations to ensure that significant changes in weather do not remain unreported. If such an observation does not reveal a significant change, it is designated as a "check observation." If a significant change has occurred, the report is treated in every way as a "SPECI observation ."

10.3.6.1

A check observation shall be taken whenever a pilot report is received from an aircraft within 1 1/2 miles of the boundary of an airfield, and the PIREP indicates that weather conditions as observed by the pilot differ significantly from those reported by the current observation, i.e., the PIREP indicated that a SPECI report may be required. This check observation may result in the transmission of a SPECI observation.

10.3.6.2

Check observations may be made on the observer's initiative.

10.3.6.2.1

The contents of check observations made at the request of a forecast office shall consist of sky condition, visibility, weather and obstruction to vision, wind, clouds and/or obscuring phenomena, and Remarks if applicable.

10.3.6.2.2

Requests for a check observation of a specific element may be limited to the item requested. For example, the control tower may request a check of the surface wind, or of the altimeter setting, and only the requested item need be observed and recorded.

10.3.7 Accident observation

Immediately upon learning of an aircraft accident, at or in the vicinity of the weather observing station, the observer shall make an accident observation unless a complete observation has been made subsequent to the accident. The accident observation shall be recorded on Form 63-2322 in Section II and it shall be as complete and accurate as possible, with particular care being taken to include in "Remarks" or under "Notes" any meteorological facts which might relate to the accident, or which might be of significance to the aircraft accident investigator.

10.3.7.1

Immediately upon completion of the accident check observation or the complete observation (see 10.3.7), the original copy of Form 63-2322 containing the record of observations until that time for that day, shall be secured under lock and key to prevent any tampering, mutilation or destruction of the original record.

Note: If any of the observed elements warrant a SPECI as defined in 10.3.5, (Criteria for taking a SPECI) a full SPECI shall be transmitted and recorded on Form 63-2322.

10.3.7.2

The remaining observations for the day shall be recorded on a new Form 63-2322 and this form shall also contain an accurate transcription of the reports which have been secured under lock and key, in order that a complete record may be forwarded to Meteorological Service of Canada Headquarters at the end of the month. There shall also be a notation on each form indicating which observations were transcribed.

10.3.7.3

Requests for weather reports and forecasts normally transmitted on Meteorological Service of Canada circuits may be answered without question. Requests for professional advice or opinion or information other than that referred to above should be forwarded to the Chairman, Transportation Safety Board of Canada (TSB) for clearance with the board.

10.3.7.4

The original of Form 63-2322, containing the accident observation, shall be released only:

  • To a TSB official, or
  • As per the instructions from either the Regional Director General, Environment Canada, or the Chairman, TSB.

Note (1): If the original is removed, a receipt or equivalent should be placed on file.

Note (2): At stations where suitable photocopying equipment is available, the observer may substitute a clean, legible photocopy in place of the original copy of Form 63-2322 referred to in 10.3.7.1, 10.3.7.4, and 10.3.7.5. The photocopy would then be used for aircraft accident investigation purposes and it would be unnecessary to transcribe reports as detailed in 10.3.7.2.

Note (3): At Department of National Defence (DND) bases, the form shall be released according to local "SOPs."

10.3.7.5

After having been admitted as evidence and returned to the meteorological office, if not required as evidence within a three-month period, the original of Form 63-2322 shall be placed on a permanent aircraft accident file.

10.3.7.6

The officer-in-charge shall interview all meteorological personnel who were on duty at the time of the accident, and write down all relevant information as derived from the various personnel responsible to them, as soon as possible after the accident. Factual information shall be clearly separated from hearsay. Rumours or theories may be recorded, but should be so designated in the notes.

10.3.8 Transmission of hourly observations

10.3.8.1

Several different methods of data entry are used to transmit hourly observations on MSC meteorological circuits, referred to as the National Computer Communications System (NCCS). The following list shows some of the data entry systems:

  • WinIDE (Windows Interactive Data Entry)
  • MIDS (Multi-purpose Informative Display System)
  • HWOS (Human Weather Observation System)

10.3.8.2

Requested check reports shall be forwarded immediately to the office making the request. Check reports taken on the observer's initiative shall be given such local distribution as the observer deems necessary.

10.4 Section I - observed data and computations

Stations which make synoptic observations shall complete the entire section (columns 1-14 and Lines 15-22) as part of the synoptic observation (see 13.3 for details). Stations which make hourly observations only, at any of the times of the main and intermediate synoptic hours, shall complete this section in part, omitting entries in columns 5 to 14.

10.4.1 Column 1 - notes

Notes on unusual weather, (see 3.12), local conditions affected by the weather etc., shall be entered in Column 1. This column shall also be used for the recording of any occurrences or events of meteorological significance, for example, damage to life or property by high winds, tornadoes or hail that cannot be recorded elsewhere on the form.

10.4.1.1 Column 1 - instrument defects and changes

Enter details of changes in thermometers and other instruments, the time at which instruments became or remained unserviceable, etc. For example: motor psychrometer unserviceable at 1800 UTC ; wind equipment remained unserviceable due to freezing rain, max thermometer XC99-0421 replaced by XC96-0075 at 1155 UTC. Similar entries are required on Form 63-2325 (see 8.1.2).

10.4.2 Columns 2, 3 and 4 - duration of weather and/or obstruction to vision

10.4.2.1 Column 2

In Column 2 record each occurrence (see 10.4.2.4 to 10.4.2.7) of any of the weather phenomena listed in 10.2.10 (except VC codes, see 10.7). The weather phenomena shall be designated by the appropriate symbols with separate entries to indicate different intensities. The symbols and possible variations in intensity are also shown in 10.2.10. These entries should be recorded in chronological order with respect to the time of beginning of the phenomenon.

10.4.2.2 Columns 3 and 4

In columns 3 and 4 record the time (UTC) of beginning and ending for each entry in Column 2. If, due to the nature of the observing program, the time(s) is (are) not known, enter "M " for missing.

10.4.2.3

When recording the beginning and ending of thunder, intermittent precipitation or showery precipitation or obstruction to vision, the record in these columns need not show, (unless there is a local need) intervals of less than 15 minutes between occurrences of thunder, precipitation or obstructions to vision. When 15 minutes have elapsed since the last occurrence of thunder, showery or intermittent precipitation or obstructions to vision, the phenomenon is considered to have ended 15 minutes ago, and the appropriate entry shall be made in Column 4.

Example (1):

example of entries into Columns 2, 3 and 4 and corresponding weather phenomena durations (See long description below)
Description of image

This illustrates 2 periods of rain and the necessary entries in Columns 2, 3 and 4. Columns 2 and 3 refer to the beginning and end; this corresponds to the left hand illustration.


View larger image

Example (1) illustrates two periods of rain and the necessary entries in columns 2, 3 and 4.

Example (2):

example of entries into Columns 2, 3 and 4 and corresponding weather phenomena durations (See long description below)
Description of image

This illustrates 5 periods of rain showers and the necessary entries in Columns 2, 3 and 4. Columns 2 and 3 refer to the beginning and end; this corresponds to the left hand illustration.


View larger image

Example (2) illustrates five periods of rain showers and the necessary entries in columns 2, 3 and 4.

Example (3):

example of entries into Columns 2, 3 and 4 and corresponding weather phenomena durations (See long description below)
Description of image

This illustrates 3 periods of thunder and the necessary entries in Columns 2, 3 and 4. Columns 2 and 3 refer to the beginning and end; this corresponds to the left hand illustration.


View larger image

Example (3) illustrates three periods of thunder and the necessary entries in columns 2, 3 and 4.

Example (4):

example of entries into Columns 2, 3 and 4 and corresponding weather phenomena durations (See long description below)
Description of image

This illustrates mist changing to fog and then changing back to mist and the necessary entries in Columns 2, 3 and 4. Columns 2 and 3 refer to the beginning and end; this corresponds to the left hand illustration.


View larger image

Example (4) illustrates mist (BR) with visibility between six miles five-eighths mile, changing to fog (FG) with visibility one-half mile or less and the necessary entries in columns 2, 3, and 4, then changing back to mist.

Note: A period of precipitation, thunder, etc., refers to the interval between the beginning and ending of the phenomenon, disregarding intervals of less than 15 minutes between occurrences. However, entries in columns 2, 3 and 4 are also required to show the duration of each intensity as illustrated (see 10.4.2.3, Example (2)).

10.4.2.4

Each occurrence of mist, haze, smoke, blowing snow, blowing sand, blowing dust, duststorm, sandstorm, dust haze, shallow fog patches, fog patches, fog covering part of aerodrome, dust/sand whirls or volcanic ash, alone or in combination with other phenomena, shall be recorded in these columns if observed with a prevailing visibility of six miles or less.

10.4.2.5

Each occurrence of fog or freezing fog, alone or in combination with other phenomena shall be recorded in these columns if observed with a prevailing visibility of 1/2 mile or less.

10.4.2.6

Each occurrence of volcanic ash, alone or in combination with other phenomena shall be recorded in these columns if observed regardless of the prevailing visibility.

10.4.2.7

Each occurrence of drifting dust, drifting sand, or drifting snow alone or in combination with other phenomena shall be recorded in these columns if observed regardless of the prevailing visibility.

10.4.2.8

If additional space is required for entries in columns 2, 3 and 4 use Column 1.

10.4.3 Hour (UTC)

No entries are required in this column; the times shown and the 24-hour value indicator are guides for subsequent entries.

10.4.3.1

Columns 5 to 14 of Form 63-2322 are not filled in at stations that do not do synoptic reports.

10.4.4 Column 5 - corrected maximum

Record the corrected reading of the maximum thermometer in degrees and tenths Celsius in the space indicated, e.g. 1.4, 0.4 etc. At the bottom of Column 5, enter the maximum temperature in degrees and tenths for the preceding 24 hours.

10.4.4.1

At stations which operate during part of the day, seven days a week but do not take an observation at 0600 UTC , the thermograph chart shall be used to obtain the maximum temperature to the nearest degree for the period between the previous reading of the maximum thermometer and 0600 UTC. Apply the appropriate correction (see 5.9.2 (3) (ii)), and record this 0600 UTC corrected value in degrees and tenths followed by the letter "E".

Example: 25.0E, -4.0E etc.

Note: It is only at 0600 UTC that an entry is required for a time when no observation was taken.

10.4.4.1.1

When the 0600 UTC maximum temperature is obtained from the thermograph chart, the thermograph chart must also be used in conjunction with the maximum thermometer to obtain the next maximum temperature. For example:

  • At 1200 UTC , the maximum thermometer reads 9.4 and it is obvious from the thermograph chart that this maximum temperature occurred between 0600 UTC and 1200 UTC. Record 9.4 as the maximum temperature at 1200 UTC.
  • At 1200 UTC the maximum thermometer reads 9.4 and it is obvious from the thermograph chart that this maximum temperature occurred before 0600 UTC. From the thermograph chart obtain the highest temperature since 0600 UTC. Apply the appropriate correction (see 5.9.2 (3) (ii)) and record the corrected reading in degrees and tenths, followed by the letter "E" as the 1200 UTC maximum temperature. Example: 15.0E, -3.0E.

10.4.4.2

If during a given period, a dry-bulb thermometer registers a higher temperature than that indicated by the maximum thermometer for the same period, record the maximum thermometer reading in brackets and immediately above, record the dry-bulb temperature in the same space. In this case the dry-bulb temperature shall be considered for coding purposes and in determining the 24-hour maximum temperature. Further details shall be recorded under "Notes," Column 1.

10.4.4.3

When the maximum thermometer is unserviceable for the entire period under consideration, and consecutive hourly dry-bulb temperatures are available, record the highest dry-bulb reading as the maximum temperature. Enclose this value in brackets and explain under "Instrument Defects and Changes," Column 1.

Note: When a serviceable maximum thermometer is available for only a portion of the period, its reading shall be entered in Column 5 and considered in conjunction with the appropriate dry-bulb readings, to determine the maximum temperature.

10.4.4.4

At stations collocated with an automatic station, the maximum temperature may, if necessary, be obtained from the input message or from either the hourly or synoptic messages generated by the automatic station. Maximum temperatures derived from automatic stations shall be recorded in degrees and tenths. A note shall be entered in Column 1 to indicate that the maximum temperature is derived from the automatic station.

10.4.4.5 Column 6 - TxTxTx - maximum temperature in degrees and tenths Celsius

The small figure inserted in the upper left hand corner of each space indicates the period preceding the time of observation for which a maximum temperature is required, except at 1200 UTC the entry in Column 6 shall be the 24-hour maximum for the 24-hour period ending six hours ago. If, however, the 0600 UTC observation was not taken, record at 1200 UTC the maximum for the previous 24 hours.

10.4.4.6

The entry in Column 6 shall be selected, without rounding, from the appropriate entries in Column 5.

10.4.5 Column 7 - corrected minimum

Record the corrected reading of the minimum thermometer in degrees and tenths Celsius in the space indicated.

Example: 1.4, 0.4 etc. At the bottom of Column 7 enter the minimum temperature in degrees and tenths for the preceding 24 hours.

10.4.5.1

At stations which operate during part of the day, seven days a week, but do not take an observation at 0600Z the thermograph chart shall be used to obtain the minimum temperature, to the nearest degree, for the period between the previous reading of the minimum thermometer and 0600 UTC. Apply the appropriate correction (see 5.9.2 (3) (ii)) and record this 0600 UTC corrected value in degrees and tenths followed by the letter "E".

Example: 15.0E, -2.0E, etc.

Note: It is only at 0600 UTC that an entry is required for a time when no observation was taken.

10.4.5.1.1

When the 0600 UTC minimum temperature is obtained from the thermograph chart, the thermograph chart must also be used in conjunction with the minimum thermometer to obtain the next minimum temperature.

Example:

  • At 1200 UTC , the minimum thermometer reads 9.4 and it is obvious from the thermograph chart that the minimum temperature occurred between 0600 UTC and 1200 UTC. Record 9.4 as the minimum temperature at 1200 UTC.
  • At 1200 UTC , the minimum thermometer reads 9.4 and it is obvious from the thermograph chart that this minimum temperature occurred before 0600 UTC. From the thermograph chart obtain the lowest temperature since 0600 UTC. Apply the appropriate correction (see 5.9.2 (3) (ii)) and record the corrected value in degrees and tenths followed by the letter "E", as the 1200 UTC minimum temperature.
    Example: 15.0E, -3.0E.

10.4.5.2

If during a given period a dry-bulb thermometer registers a lower temperature than that indicated by the minimum thermometer for the same period, record the minimum thermometer reading in brackets and in the same space and immediately above, record the dry-bulb temperature. In this case the dry-bulb temperature shall be considered for coding purposes and in determining the 24-hour minimum temperature. Further details shall be recorded under "Notes", Column 1.

10.4.5.3

When the minimum thermometer is unserviceable for the entire period under consideration and consecutive hourly dry-bulb readings are available, record the lowest dry-bulb reading as the minimum temperature. Enclose this value in brackets and explain under "Instrument Defects and Changes", Column 1.

Note: When a serviceable minimum thermometer is available for only a portion of the period, its reading shall be entered in Column 7 and considered in conjunction with the appropriate dry-bulb readings, to determine the minimum temperature.

10.4.5.4

At stations collocated with an automatic station, the minimum temperature may, if necessary, be obtained from the input message or from either the hourly or synoptic messages generated by the automatic station. Minimum temperatures derived from automatic stations shall be recorded in degrees and tenths.

Example: -27.4, -23.0.

A note shall be entered in Column 1 to indicate that the minimum temperature is derived from the automatic station.

10.4.6 Column 8 - TnTnTn - minimum temperature in degrees and tenths Celsius

The small figure inserted in the upper left-hand corner of each space indicates the period preceding the time of observation for which a minimum temperature is required. The entry in Column 8 shall be selected, without rounding, from the appropriate entries in Column 7.

Note: At 1200 and 1800 UTC , it is necessary to check the entries recorded in Column 7 of Form 63-2322 for the previous day, e.g., at 1200 UTC the six-hour minimum recorded at 0600 UTC of the previous day shall also be considered when determining the entry in Column 8.

10.4.7 Column 9 - snowfall

Enter the amount, (see 3.7.6 and 3.7.7) in centimetres and tenths (nearest 0.2 cm) in the space indicated. When there is less than a measurable amount, that is, less than 0.2 cm, record this as a "trace" by entering "TR". Enter "0" for none.

10.4.7.1

At the bottom of Column 9 enter the total amount of snowfall for the previous 24 hours. Enter "TR" for a trace; enter "0" for none1.

Note: The addition of two or more "TR" amounts yields only a "TR".

10.4.7.2

Stations which operate during part of the day, seven days a week, but do not take the 0600 UTC observation, shall estimate the amount of snowfall for the period between the time of the previous snowfall measurement and 0600 UTC. Under these circumstances the value entered for 0600 UTC , if greater than a trace, shall be followed by the letter "E".

Note: It is only at 0600 UTC that an entry is required for a time when no observation was taken.

10.4.7.2.1

When the snowfall for 0600 UTC was determined by estimation (see 10.4.7.2), the snowfall amount for the next observation shall be the measured amount minus the amount assigned to the 0600 UTC observation.

10.4.8 Column 10 - snowfall (water equivalent)

Enter the amount, in millimetres and tenths, in the space indicated. When there is less than a measurable amount, that is, less than 0.2 mm, record this as a "trace" by entering "TR". Enter "0" for none. At the 0600 UTC observation, compute the total amount of snowfall water equivalent for the preceding 24-hour period and enter this value at the bottom of Column 10. Enter "TR" for a trace1. Enter "0" for none.

1Note: The addition of two or more "TR" amounts yields only a "TR".

2 Note: At stations equipped with a snow gauge, this is the "measured" water equivalent. At stations not equipped with a snow gauge, it is the "estimated" (snowfall divided by ten and converted to mm) water equivalent.

10.4.9 Column 11 - rainfall

Enter the amount in millimetres and tenths in the space indicated.

Example: 12.0, 0.4 etc.

When there is less than a measurable amount, that is, less than 0.2 mm, record this as a trace by entering "TR". Enter "0" for none.

10.4.9.1

When the observer is certain that the water measured in the rain gauge has resulted from the formation of dew alone, the word "dew" shall be written in brackets before the amount, e.g., (dew) 0.2.

10.4.9.2

At the bottom of Column 11, enter the total amount of rainfall (less dew) for the preceding 24-hour period. Enter "TR" for a trace1. Enter "0" for none.

10.4.9.3

Stations which operate during part of the day, seven days a week, but do not take the 0600 UTC observation, shall determine from the recording rain gauge (or from the recording rain gauge of a collocated automatic station), or by estimation if necessary, the amount of rainfall for the period between the time of the previous standard gauge measurement and 0600 UTC. Under these conditions, the value entered at 0600 UTC, if greater than a trace, shall be followed by the letter "E".

Note: It is only at 0600 UTC that an entry is required for a time when no observation was taken.

10.4.9.3.1

When the rainfall for 0600 UTC was determined from a recorder chart, collocated automatic station, or by estimation, the rainfall amount for the next observation shall be the measured amount from the standard gauge minus the amount assigned to the 0600 UTC observation.

10.4.10 Column 12 - total precipitation

Enter the amount in millimetres and tenths in the space indicated. Example: 8.2, 0.4, etc. This value is the sum of the water equivalent and rainfall as entered in columns 10 and 11. When there is less than a measurable amount (less than 0.2 mm) record this as a trace by entering "TR". Enter "0" for none. At the bottom of Column 12 enter the total amount of precipitation for the preceding 24 hours.

10.4.10.1

When dew occurs alone, its amount shall not be included in the total precipitation recorded in Column 12.

10.4.10.2

The total amount of precipitation for the preceding 24 hours shall agree with the sum of the 24-hour snowfall water equivalent and the 24-hour rainfall as entered at the bottom of columns 10 and 11.

10.4.11 Column 13 - total 24-hour precipitation

Entries are made in this column only at those stations at which synoptic observations are transmitted, see 13.3.12.

10.4.12 Column 14 - depth of snow on ground

Enter the total depth of snow on the ground in whole centimetres. Enter "TR" for a trace (less than 0.5 cm) and enter "0" for none.

10.4.13 Time (UTC)

Lines 15 to 22 shall be completed whenever an observation is made at 0900, 1200, 1500, 1800, 2100, 0000, 0300 or 0600 UTC. Space has been left in these time blocks for observers to fill in the current dry-bulb temperature (T0) and the temperature of 12 hours ago (T-12). The small numbers beneath the 0900, 1200, etc., serve as reminders of the times to which temperatures of 12 hours ago apply.

Example: The temperature of 12 hours ago which should be used at 0900 UTC , is the temperature from the previous day at 2100 UTC.

10.4.13.1

At sites equipped with data entry screens that compute pressure, entries to lines 15 to 17 and 19 to 22 of Form 63-2322 are not required. Line 18 shall be completed as per 10.4.16 and 10.4.17. Entries in Column 33 (sea-level pressure), Column 39 (altimeter setting), Column 41 (Remarks - reduction of pressure to sea level only when manually calculated, station pressure) and Column 42 (appp) are still required and will be obtained from the data entry screen.

10.4.13.1.1

If, for any reason, tables are used to do manual pressure calculations (at sites equipped with data entry screens that compute pressure), complete lines 15-22. Entries in Column 33 (sea-level pressure), Column 39 (altimeter setting), Column 41 (reduction to sea-level reported in accordance with 10.2.11.1), and Column 42 (appp), will be obtained from the calculated values in Lines 15-22. Appropriate entries are also required in Column 1, Notes, and on Form 63-2325 ("Monthly Summary of Instrument Malfunctions, Changes and New Installations") indicating the hours that the tables were used for pressure computations.

10.4.13.1.2

At sites where an AWOS is used to report station pressure, the value will be entered on Line 20.

10.4.14 Line 15 - sum

Enter the sum of the dry-bulb temperature of 12 hours previously and the current dry-bulb temperature.

Note: When the temperature of 12 hours ago cannot be obtained from a dry-bulb reading, a collocated automatic station, or a thermograph, it shall be estimated (see 4.2.3.2).

10.4.15 Line 16 - mean

Divide the sum by two and round to one decimal place to obtain a temperature mean and record this value. This mean shall be used for computing the reduction to sea level (line 21) using the tables supplied for this purpose.

10.4.16 Line 17 - attached thermometer

Entry not required when digital barometer in use.

10.4.17 Line 18 - barometer as read

Enter the barometer as read (nearest tenth hPa). Example: 968.9

10.4.18 Line 19 - total correction

From the table for the reduction of the barometer reading to station pressure, determine the total correction and enter this value using the appropriate sign. Example: +1.2, -0.7 etc.

10.4.19 Line 20 - station pressure

Compute the station pressure from the barometer as read and the total correction. Record the station pressure (nearest tenth hPa).

10.4.20 Line 21 - reduction to sea level

Enter the reduction to sea level value as determined from the sea level reduction table (ssee 4.2.3).

10.4.21 Line 22 - sea level pressure

Add the reduction to sea level to the station pressure to obtain the sea level pressure. Record the sea level pressure (nearest tenth hPa). Example: 1018.9

10.5 Section IV

See 13.6 for the summary for the climatological day ending at 0600 UTC.

Note: See 13.6.13.1 to 13.6.13.6for more detailed instructions about programs A, B, C, D, E, and F.

10.5.1 Column 69 - checked by

The Officer-in-Charge or a designated staff member shall check, preferably on a daily basis, the accuracy and legibility of all data recorded on Form 63-2322. Upon completion of this check, the reviewing officer shall record their name and their signature in Column 69. (Column 69 is found in the extreme upper left corner of the form).

10.6 Typical Entries - Form 63-2322

10.6.1 Example 1 - Completed Form 63-2322

Example of 63-2322 Form (See long description below)
Description of image

The first form displays the left half of a typical entry into the surface weather record form 2322. Contains an area to mark down who checked, certified, completed and corrected the form. Section I, Observed Data and Computations, contains a section for Notes and Instrument Defects and Changes, as well as Duration of Weather and/or Obstructions to vision. Section II, Hourly Observations, contains columns for Corrected Wet Bulb, Relative Humidity, Total Opacity, Total Amount, Type, Date, Hour (UTC), Sky Condition, Visibility, Weather and Obstructions to vision, Sea Level Pressure. Section III, Coded Synoptic Reports contains columns for Hour, Snowfall, Water Equivalent, Rainfall, Total Precipitation, 24 hour Precipitation, Depth Snow on ground, and various codes. Section IV, Summary for the Climatological Day contains columns for Day, Temperature, Relative Humidity and 6 - hour to.

Example of 63-2322 Form (See long description below)
Description of image

The first form displays the right half of a typical entry into the surface weather record form 2322. Contains fields for Dry Bulb and Dewpoint Temperature, Wind direction, speed and character, Altimeter Setting, Obscuring Phenomena, Remarks, Tendency, Observer Initials. Underneath contains columns for various codes. Underneath contains columns for Amount of Precipitation, Depth of Snow, Day with Thunderstorms, Freezing rain, Hail, Fog, Smoke Dust Haze, Blowing Dust, Blowing Sand, Blowing Snow, Mean Wind, and Peak Wind Speed.

10.6.2 Example 2 - Completed Form 63-2322

Example of 63-2322 Form (See long description below)
Description of image

The first form displays the left half of a typical entry into the surface weather record form 2322. Contains an area to mark down who checked, certified, completed and corrected the form. Section I, Observed Data and Computations, contains a section for Notes and Instrument Defects and Changes, as well as Duration of Weather and/or Obstructions to vision. Section II, Hourly Observations, contains columns for Corrected Wet Bulb, Relative Humidity, Total Opacity, Total Amount, Type, Date, Hour (UTC), Sky Condition, Visibility, Weather and Obstructions to vision, Sea Level Pressure. Section III, Coded Synoptic Reports contains columns for Hour, Snowfall, Water Equivalent, Rainfall, Total Precipitation, 24 hour Precipitation, Depth Snow on ground, and various codes. Section IV, Summary for the Climatological Day contains columns for Day, Temperature, Relative Humidity and 6 - hour to.

Example of 63-2322 Form (See long description below)
Description of image

The first form displays the right half of a typical entry into the surface weather record form 2322. Contains fields for Dry Bulb and Dewpoint Temperature, Wind direction, speed and character, Altimeter Setting, Obscuring Phenomena, Remarks, Tendency, Observer Initials. Underneath contains columns for various codes. Underneath contains columns for Amount of Precipitation, Depth of Snow, Day with Thunderstorms, Freezing rain, Hail, Fog, Smoke Dust Haze, Blowing Dust, Blowing Sand, Blowing Snow, Mean Wind, and Peak Wind Speed.

10.7 Summary: surface weather record; acceptable entries for Column 2

Acceptable Entries for Column 2
Phenomena Code
Tornado +FC (TORNADO in Remarks)
Waterspout +FC (WATERSPOUT in Remarks)
Funnel Cloud FC (FUNNEL CLOUD in Remarks)
Thunderstorm TS
Rain -RA , RA , +RA
Rain Showers -SHRA , SHRA , +SHRA
Drizzle -DZ , DZ , +DZ
Freezing Rain -FZRA , FZRA , +FZRA
Freezing Drizzle -FZDZ , FZDZ , +FZDZ
Snow -SN , SN , +SN
Snow Showers -SHSN , SHSN , +SHSN
Snow Grains -SG , SG , +SG
Ice Crystals IC
Ice Pellets -PL, PL , +PL
Ice Pellet Showers -SHPL , SHPL , +SHPL
Hail (diameter of largest stone =5 mm) -SHGR , SHGR , +SHGR
Hail (diameter of largest stone <5 mm) -SHGS , SHGS , +SHGS
Snow Pellets -SHGS , SHGS , +SHGS
Fog (prevailing visibility <5/8 mile) FG
Freezing Fog (prevailing visibility <5/8 mi., temperature <0 °C and = -30 °C) FZFG
Shallow Fog MIFG
Partial Fog PRFG
Fog Patches BCFG
Mist (visibility 5/8 to 6 mi.) BR
Haze HZ
Smoke FU
Blowing Snow BLSN , +BLSN
Blowing Sand BLSA , +BLSA
Blowing Dust BLDU , +BLDU
Duststorm DS , +DS
Sandstorm SS , +SS
Dust/Sand whirls PO
Dust Haze DU
Drifting Dust DRDU
Drifting Sand DRSA
Drifting Snow DRSN
Volcanic Ash VA

 

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