As of Feb. 9 more than 78 percent of all the Great Lakes surface was frozen over, one of the highest numbers in 20 years. Yet, the unseasonably early cold and polar vortex had little effect on Lake Ontario, and lake-effect snowstorms continue to bring more snow to the Watertown area.
On Lake Ontario, a small concentration of ice has formed near Cape Vincent, but the lake remains the most open of the lakes.
Lake-effect snowstorms are caused by the warm surface temperatures of the lake. When that meets the cold air temperature, the air condenses and rises and that causes the clouds to form, meteorologist Jim A. Mitchell with the National Weather Service said.
In January, Watertown received over 72 inches of snow, more than the 43 inches in Fulton, where Mr. Mitchell said has historically seen more snowfall.
This year we have a persistent flow of cold air out of northern Canada that is directing the bands right to Watertown. Wherever the winds going, thats where the band will go, Mr. Mitchell said.
The combination of the lower air temperatures and Lake Ontarios current, which keeps lake water constantly moving from the bottom to the surface and keeps the temperature relatively warm, makes it harder for Lake Ontario to freeze, according to Mr. Mitchell.
According to the Great Lakes Environmental Research Laboratory, as of Feb. 9, more than 78.4 percent of the Great Lakes were covered in ice. Though lakes Superior, Michigan, Huron and Erie have mostly frozen over, the early winter polar vortex didnt have the same freezing effect on Lake Ontario.
Dan P. Kelly, meteorologist with the National Weather Service, said the water flow in Lake Ontario known as up-welling also circulates warmer water from the lakes bottom to the surface. Mr. Kelly said this keeps the water at a warmer temperature and in constant fluctuation.
If the water temperature was lower, the lake could freeze, Mr. Mitchell said.
According to the GLERL website, ice coverage for Lake Ontario is historically low. In 2010 the lake had a high coverage of less than 10 percent preceded by a high of 30 percent in 2011. Since 1973, lakes Erie, Huron and Superior have recorded average ice coverage above the average 38.4 percent for 2013.
Mr. Mitchell said over the next 10 days the low temperatures and snowfall trend should continue.
Overall, the air temperature has been a lot colder in the last few months but it is about where it should be, Mr. Mitchell said. In the last five years, its been much warmer than average, so the weather now feels abnormal.
Since lakes Huron, Michigan and Superior are farther north than Ontario, he said, the temperatures are lower and they therefore more easily freeze. Lake Erie, which is relatively shallow, is also easier to freeze than Lake Ontario.
Weve been so entrenched with cold weather this month there hasnt been a break, Mr. Mitchell said. Over the next 10 days it doesnt look like there is going to be any let-up.
Mr. Kelly said for the month of January, the Watertown area received 76.3 inches of snow, and Fulton received 43.1 inches.
The wind direction steers the band of the lake-effect snow; the bands follow the wind, Mr. Mitchell said. Its just the pattern weve been in.
Mr. Mitchell said the famous lake-effect snowstorms the region has been increasingly experiencing this winter are due to the warm surface temperature of the lake and the colder air.
The highest amount of ice formation usually occurs in March, so there is still time for more ice to form.