Sunday, February 19, 2012

The lack of ice cover on the Great Lakes.

Hi it's Rebecca again, this time I will discuss the amount of ice on the Great Lakes. The winter of 2011-2012 in the Northeast has (so far) seen temperatures above normal and snowfall below normal. The same can be said for the entire lower 48 for the most part, this includes the Great Lakes. From December 1 thru this week in February the temps have been running 5-10 degrees above normal, from New York State and northwestern Pennsylvania to northern Wisconsin and northeastern Minnesota.  Because of this ice on the Great Lakes much lower than it is this time of year. Right now, the amount of ice cover on the Great Lakes is at historic proportions. This is a direct result of the warmer than normal temperatures the region has been experiencing. To give you an idea how warm it's been, last month was the fourth-warmest January on record for the contiguous United States. We've only had a few cold waves as well. This can be shown in figures released by Environment Canada as of Feb. 5, 2012, just over 5 percent of the Great Lakes waters were covered in ice.

Image credit for the following images is Environment Canada.

                 Here is a chart that shows the percentage of ice cover for the last 30 years or so.

As you can see in this chart made up by Environment Canada. Only during the winter of 2005-2006 was the precentage of ice cover less than 5%. It also shows that the winter of 2001-2002 had ice cover of less than 10%

To put this into perspective, As a rule, By this time of year,  the percentage of ice on the Great Lakes is around 30 percent. In a normal year by the middle of March the coverage is close to 40%. The alarming thing about this year is the ice cover on the great lakes may have already peaked; at least according to  Canadian Weather Expert Brett Anderson, from everything I've been looking at, I have to agree with him.
In the following map you can see where the ice cover is on the Great Lakes:

The blue or white colors indicate very little in the way of ice. I looked but I could not find a map that showed ice cover at the same time last year.

The next map shows the departure in ice cover compared to normal.

The color red shows departures in ice coverage of around 70% compared to normal. The biggest difference is Lake Erie. Erie being the shallowest of the five lakes, normally is well on it's way to being frozen over, by this time of year. This is not just happening on the Great Lakes; those who live around the Champlain Valley are all too aware the same thing is happening to Lake Champlain as well. In fact most lakes around the country are having the same problem.  

What effect will the lack of ice have?

Because it's rare to have this amount of ice cover; it's unclear if the lack of ice will have a major effect on the environment. I have seen studies about German lakes that show less ice causes plankton to grow at different times than in the past. Will it be the same here? Scientists are still trying to determine how less ice would affect a variety of species. According to research form the SUNY College of Environmental Science and Forestry (ESF), the effect of less ice cover will drastically affect aquatic insects, fish, and submergend vegetation that is typically protected by ice.

There are two camps when it comes to this issue. Many feel like Brian Chipman, a fisheries biologist. He thinks cold water fish won't suffer at all with less ice, he feels the lakes are immense, with plenty of deep, cold water for these species regardless of whether the lake freezes. However, the Nature Conservancy report disagrees, saying there is the potential for harm to cold-water fish if ice continues to diminish, because they might not be able to adapt quickly enough to changing water temperatures or ice cover. From an angler's standpoint, the lack of ice fishing opportunities could mean increased survival of some game species such as northern pike. Overall, it might be hard to figure out effects caused by a lack of lake ice or other factors, such as warmer water temperatures.

Lake Effect Snow
The lack of ice on the Great Lakes could impact late season lake snow events. When there is less ice on the big lakes it tends to produce more lake-effect snow. Why? simply put, with more warm water exposed; the low pressure systems, fronts, and upper level disturbances have more moisture to work with. move over. more can all pick up additional moisture from the unfrozen lake and produce more snow inland. If there's a lot of ice cover there's less evaporation and therefore less lake-effect snow. Because of this, the lake snow belts are more at risk for unusually heavy late season lake effect snow events. That is if we can tap into enough of that cold air to the north. For lake effect snow to happen, the air moving over the lake has to be colder than the water by about 23 degrees Fahrenheit. At the time I'm typing this, the average water temps are 37 degrees for Lake Ontario  and  34 degrees for Lake Erie. So in order to get decent lake effect snows, the air moving over the lakes would have to be at least in the low teens thru the upper single numbers. The more time that passes the less the chances of that happening are.

If you want to know more about lake effect snow. Check out this link.
Lake Effect Snow

Here is a link to high resolution images of the Great Lakes.

MODIS Satellite Images

Well I hope you enjoyed reading this.


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