Great Lakes quarterly climate impacts and outlook: March 2014
Great Lakes Significant Events - for December 2013 - February 2014
Winter 2013-2014 has been unusually cold for the Great Lakes basin, especially when compared to recent years. An arctic blast in early January blanketed the Great Lakes region and sent sub-freezing temperatures as far south as Florida. These freezing temperatures were the result of a southward dip of the polar vortex. The polar vortex is a permanent fixture of the atmospheric circulation at the poles, but in early January 2014 the polar vortex weakened, allowing fragments of cold air to surge into the middle latitudes (see figure 1 below). This surge of cold air via the polar vortex occurred on a number of other occasions this winter as well. Since the polar vortex is permanent in the atmosphere, there will always be a chance for this cold variability today and in the future.
A season of unusually cold weather in the Great Lakes basin is not a sign that the century long trend of rising temperatures has reversed. In fact, while Canada and the eastern U.S. froze at times this winter, many locations including Alaska and Europe, were experiencing unseasonably warm temperatures.
On December 20th-23rd, a damaging ice storm impacted southern Ontario, with ice buildup ranging from 15-30 mm (0.6-1.2 in) throughout the region. Total insured losses are estimated at $200 million (CAD) for this region, according to the Insurance Bureau of Canada.
Figure 1: Polar Vortex
Left: wavy polar vortex configuration (January 5, 2014)
Right: more typical, compact polar vortex configuration (November 14-16, 2013)
Long Description of Figure 1
Two global maps of the northern hemisphere side by side. The map on the right depicts a more typical compact polar vortex on November 14 to 16. The shades of purple indicate the location of the polar vortex which is concentrated over the Arctic Ocean and extending south into northern Russia, northern Canada and Alaska. The map on the left depicts a wavy configuration of the polar vortex that occurred on January 5th. The shades of purple indicate that the polar vortex extended as far south as central Canada, the U.S. Midwest, northeastern Asia and northern Atlantic Ocean.
Regional Climate Overview - for December 2013 - February 2014
Great Lakes Ice Cover
As of February 28th, the maximum extent of ice cover on the Great Lakes this winter was 88.4%, making it the 4th highest since 1973. The record ice cover of 94.7% occurred in 1979. Ice cover usually begins in mid-December, but this winter season it was reported by the end of November. Three of the Great Lakes (Superior, Huron, and Erie) became 90% or more ice covered by the end of winter, which usually does not occur.
Long-term average based on 1973-2013
Ice Cover: Difference from Average (%)
Figure 2: Ice Cover: Difference from Average (%) - Dec. 1, 2013-Feb. 28, 2014
Long Description of Figure 2
Map of the Great Lakes showing the ice cover difference from the average as a percentage. Dark Green and Blue depicts ice cover was 15% to 45% greater than average and this occurred in most of Lakes Superior, Huron, and Erie and most of the Lake Michigan shoreline. Light Green depicts ice cover was 0% to 15% greater than average and this occurred in Lake Michigan, Georgian Bay, the southeastern shoreline of both Lakes Huron and Erie and northeastern Lake Ontario. Yellow depicts ice cover was 0% to 15% less than average and this occurred in central Lake Michigan and most of Lake Ontario.
Great Lakes Water Levels
Levels of all the Great Lakes remain above last year’s levels at the beginning of March. Snowy, cold weather and significant ice cover contributed to Lake Superior finishing the quarter near the long-term average, 32 cm (12.6 in) above last year’s level and the highest at this time of year since 2005. The other lakes received near-normal water supplies. At the end of February, Lake Michigan-Huron was 32 cm (12.6 in) below average, but 33 cm (13 in) higher than at this time last year. Lake Erie and Lake Ontario remained near average throughout the quarter and were within 5 cm (~ 2 in) of their average levels to start March.
Water level statistics based on 1918-2013.
Most of the region saw above normal snowfall during winter, with departures from 100% to 200% of normal. However, generally areas northeast and on the southern side of Lake Superior only received 50% to 75% of normal winter snowfall.
Snowfall normals based on 1981-2010.
Snowfall: Percent of Normal (%)
Figure 3: Snowfall: Percent of Normal (%) - Dec. 1, 2013-Feb. 28, 2014
Long Description of Figure 3
Map of Great Lakes showing snowfall distribution for the autumn months. Green and dark green areas depict greater than normal percentages of snowfall and are concentrated in most areas of the Great Lakes region with greater concentrations in the west, south and central portions of the Great Lakes region. Less than normal percentages of snowfall are depicted in brown and beige and are concentrated in the northeast portion of the Great Lakes region.
The winter season was the coldest in 20 years for the Great Lakes region. The coldest areas surrounded the western half of Lake Superior, where departures were greater than -5°C (-9°F). Areas surrounding the eastern half of Lake Ontario had the lowest departures, from -0.5°C to -2°C (-0.9°F to -3.6°F).
Temperature normals based on 1981-2010.
Temperature: Departure from Normal (°)
Figure 4: Temperature: Departure from Normal (°) - Dec. 1, 2013-Feb. 28, 2014
Long Description of Figure 4
Map of the Great Lakes showing the temperature departures from normal in degrees Celsius. Blue and purple areas depict areas where the temperature was -2°C to -5°C (-3.6°F to -9°F) below normal and this occurred throughout the entire Great Lakes region with colder temperatures in the west and central portions of the region. Light purple and white areas depict areas where the temperature was near normal to -1°C (-1.8°F) and this occurred in the eastern portion of the Great Lakes region and into Quebec.
Regional Impacts - for December 2013 - November 2014
Impacts of Unseasonably Cold Temperatures and Significant Ice Cover
Ice shoves from lakes Ontario and Erie caused localized flooding in some areas in January and February. Ice shoves result from strong winds pushing lake ice sheets into adjacent embayments and downstream. Flood-impacted areas included along the Niagara River, Rocky and Maumee rivers in Ohio, and North Sandy Pond in New York.
Early onset and extensive ice cover has made this winter the most challenging for the shipping industry in about 24 years, according to the president of the Canadian Shipowners’ Association. This not only impacts the freight communities, but also the industries that use the cargo freighters are carrying.
During the December ice storm, Toronto suffered extensive and long-term losses to their urban tree canopy as a result of ice buildup ranging between 15-30 mm (0.6-1.2 in). Estimates say that 20% tree canopy has been lost city wide, with up to 50-80% on some streets. Other impacts during this storm include prolonged power outages that affected 600,000 households for 3-10 days. Also, two fatalities due to carbon monoxide poisoning.
Due to the blockage of water intakes on some of the Great Lakes from ice, officials in water utility departments along the lakes could not pump water into their plants for several hours in early January.
The cold temperatures produced sufficient ice on Lake Superior to allow over 85,000 visitors to trudge over the lake to explore the amazing ice cave formations on the Apostle Islands, giving this region an estimated economic boost of $10 million (USD) according to the Bayfield Chamber of Commerce and Visitor Bureau. This is the first time in 5 years the ice has been firm enough to allow passage. Agriculture may also benefit since cold temperatures make pests like the emerald ash borer easier to manage and slow the migration of invasive species.
The ice cover on the Great Lakes this winter may help raise persistent low water levels on the upper Great Lakes. In addition, lake whitefish abundance is positively related to ice cover over near shore spawning grounds, as ice helps to reduce the potential for dislodging of eggs from turbulent waves. An ice bridge formed between Isle Royale (MI) and the mainlands, allowing for the passage of species, particularly wolves and the potential diversification of the gene pool on the island.
Regional Outlook - for April - June 2014
Ice cover on the Great Lakes is naturally variable from year to year. Typically, maximum ice occurs on lakes Michigan, Huron, Ontario, and Erie in mid-February and in early March on Lake Superior. However, the cold temperatures and extensive ice cover this winter may delay start of ice breakup by two or three weeks. In addition, fog may be an issue in the coming months in the Great Lakes region as it is going to take longer than normal for the ice to melt. The significant ice cover this winter increases the risk for break-up ice jamming in adjacent embayments and tributaries, increasing the risk for flooding in these areas. However, the risk is reduced if the ice thaws gradually.
Lake Level Outlook
Current projections for April-June indicate that levels on lakes Superior, Erie and Ontario will remain near average unless exceedingly wet or dry water supply conditions are experienced. On the other hand, even the wettest scenarios suggest levels on Lake Michigan-Huron will remain below average, but levels are expected to remain higher than they were last spring. The range of probable levels on each lake are shown below.
|Lake||Forecasted high compared to the long-term average in centimetres||Forecasted low compared to the long-term average in centimetres||Forecasted high compared to the long-term average in inches||Forecasted low compared to the long-term average in inches|
|Superior||+8 cm above||-12 cm below||+3.2 in above||-4.7 in below|
|Huron-Michigan||-14 cm below||-46 cm below||-5.5 in below||-18.1 in below|
|Erie||+13 cm above||-28 cm below||+5.1 in above||-11 in below|
|Ontario||+19 cm above||-28 cm below||+7.5 in above||-11 in below|
Table 1: Forecast of Spring 2014 Water Levels (compared to the long-term average)
Outlook from the US Army Corps of Engineers and Environment Canada (Apr-June 2014)
Long Description of Table 1
The columns are as follows: Lake; Forecasted high compared to the long-term average in centimetres; Forecasted low compared to the long-term average in centimetres; Forecasted high compared to the long-term average in inches; Forecasted low compared to the long-term average in inches.
The Lakes are as follows: Superior, Huron-Michigan, Erie and Ontario.
For Lake Superior, the forecasted high is 8 centimetres (3.2 inches) above the long term average. The forecasted low is 12 centimetres (4.7 inches) below the long term average.
For Lakes Huron-Michigan the forecasted high is 14 centimetres (5.5 inches) below the long-term average. The forecasted low is 46 centimeters (18.1 inches) below the long-term average.
For Lake Erie the forecasted high is 13 centimeters (5.1 inches) above the long-term average. The forecasted low is 28 centimeters (11 inches) below the long-term average.
For Lake Ontario the forecasted high is 19 centimeters (7.5 inches) above the long-term average. The forecasted low is 28 centimeters (11 inches) below the long-term average.
Temperature & Precipitation Outlook
The NOAA Climate Prediction Center is forecasting greater chances for below normal spring temperatures in the U.S. Great Lakes basin, and equal chances for either below, near, or above normal precipitation.
Environment Canada is forecasting equal chances for either below, near, or above normal temperature and precipitation in the Canadian Great Lakes basin for April through June 2014.
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