Barny Wiggin, former Meteorologist-In-Charge at the NWS Office in Buffalo
was once quoted as saying that the weather often "clears up stormy" to
the lee of the Great Lakes during the winter. In particular, long after
the passage of cold fronts across the region, the relatively warm waters
of the Great Lakes often create convective instability in an otherwise
stable, arctic or polar continental airmass. So while other parts of the
northeastern U.S. are clearing up after a recent cold frontal passage,
Great Lakes communities wait for the lake effect snow machine to fire up!
Basically there are a couple of main ingredients that you need to produce
lake effect snow. The first is a relatively warm body of water (aka
Great Lake). The second ingredient is a source of cold air.
In the Great Lakes Region, that source comes from the high latitudes of
North America where arctic airmasses often "spill southward" over those
warm bodies of water. Heat and moisture from the warm lakes rises
into the "modified" arctic air where it then cools and condenses into snow
clouds. The prevailing wind direction through the depth of the snow
clouds (third ingredient!!) determines where the snow will occur.
Lake Effect Snows describe mesoscale convective snow events that occur
in the Great Lakes Region. However, common sense would suggest that
these types of snowstorms should occur wherever you get cold air "channeling"
across a warm body of water. We have indicated some of the other locations
on Earth where these snows occur, including such diverse places as the
Great Salt Lake in the U.S., parts of Japan, Korea and Scandinavia to name
a few, just click the above maps and see!
"Lake Effect" weather does not only occur during the Fall and Winter.
The Great Lakes influence the local climate throughout the entire year.
There are many positive impacts that the lakes have on the area climate.
Winter snows are a boon to the local skiing industry, which boasts some
of the best slopes in the east. At other times of the year the moderating
effects of the marine climate allow for the cultivation of excellent fruit
and vegetable crops, and the cooling effects of the lakes during the summer
months provide a natural air conditioner to the region.
Lake Effect Snow contributes significantly to the total seasonal snowfall in Western and Central New York. In fact, the higher elevations east of Lake Ontario get over 200 inches of snow annually, making that area the snowiest populated region to the east of the Rocky Mountains!