Guide to marine weather forecasts: chapter 12

Localized Warnings and Watches

The terms “localized warning” and “localized watch” in this context means that the geographic extent to which the localized warning or watch applies is of smaller scale. Localized warnings or watches would be issued for potentially hazardous marine weather events that only affect a localized portion of the marine district.

Localized Marine Warnings

Localized warnings are issued for the following marine weather events:

• Tornado warning: Issued when tornados are forecast or observed over a localized marine area, or when an existing tornado is moving from land to an adjacent marine area.
• Squall warning: Issued for forecast or observed wind gusts of 34 knots or greater that are associated with a line, or an organized area, of thunderstorms.
• High water level warning*: Issued to warn mariners and coastal populations of potential impacts caused by abnormally high water levels or waves along coastal or shoreline areas.
  * Note: Issued only in Atlantic Region.
• Special marine warning: Issued to warn mariners of any undefined marine weather-related phenomenon that could pose a hazard to marine navigation or safety.

Localized Marine Watches

Localized watches are issued if conditions are favourable for the development of the potentially hazardous marine weather events. The following watches may be issued:

• Tornado watch: Issued to give advance notice of conditions that are favourable for the localized development of tornados over or in the vicinity of a marine area.
• Squall watch: Issued to give advance notice of conditions that are favourable for the development of squalls.
• Waterspout watch (cold air waterspout): Issued to give advance notice of conditions favourable for the development of waterspouts over a marine area (See Waterspout.).
• Special marine watch: Issued to notify mariners that conditions are favourable for the development off any undefined marine weather-related phenomenon that could pose a hazard to marine navigation or safety.

Note that High water level watches are not issued.

Localized Warnings/Watches Appearance in Text Bulletins

In the text bulletin of the regular or updated marine forecast, localized warnings and watches in effect will be stated in a headline immediately after the marine district name(s) to which the localized warnings or watches apply.

• Example: Localized warning/watch text bulletin.

WHCN13 CWNT 051715
Marine warning for the Western Arctic waterway issued by Environment Canada at 2:15 p.m. MDT Monday 5 June 2006.

For immediate broadcast

Squall warning for :
=New= Tuktoyaktuk.

       In effect from 2:15 p.m. to 4:00 p.m.

Squall watch for :
           Baillie.

       In effect from 2:15 p.m. to 8:00 p.m
-----------------------------------------------
Watches/warnings ended

Squall warning ended for :
           Mackenzie.
-----------------------------------------------
==Discussion==
Scattered thunderstorms will accompany a cold front crossing southwestern waters this afternoon. Winds gusting to 35 knots or more are forecast in association with the thunderstorms.

This is a warning that potentially hazardous marine weather is imminent. Mariners are advised to take necessary safety precautions and monitor the forecast for updated warnings.

End

Localized Warnings/Watches Appearance on Weatheroffice

On EC’s Weather.gc.ca marine forecast website, localized warnings in effect will be highlighted by red banners immediately below the marine district name(s) to which the localized marine warnings apply. Localized marine watches will be highlighted by yellow banners immediately below the marine district name(s) to which the localized watch(es) apply.

Clicking on either of these banners will navigate the webpage user to detailed information regarding the localized warning or watch in effect. This information is located under the Warnings Tab on the relevant marine district’s Forecast page.