are famous for the snowstorms they spawn. Heavy snows regularly fall in north-
ern Wisconsin, northern Illinois, Indiana, Ohio, Pennsylvania, and New York
state, as well as a large part of Michigan. The most dramatic accumulations occur
along the southern and eastern shores of the lakes. This is called lake-effect snow.
Lake-effect snow events commonly take place following the cold front of a
low-pressure system. A strong wind, blowing from the northwest toward the
southeast, howls across the large expanse of open water, picking up moisture. The
water precipitates as snow over the land areas on the leeward sides of the lakes.
Great Lakes snowstorms can produce accumulations well in excess of 1 m (39 in)
within a couple of days. The problem is often compounded by bitter cold tem-
peratures and by high winds. This creates dangerous blizzard conditions.
A series of storms spawned by Lake Erie in 1977 gave the city of Buffalo,
New York, a massive blanketing of snow. The dry, powdery snow drifted com-
pletely over cars and trucks, whipped along by winds that gusted to about 70 kt
(80 mi/h). The temperature fell far below freezing. Visibility was zero.
In recent decades, the consequences of lake-effect snowstorms have been
increasing because of the activities of humans. There are two reasons for this.
First, the shores of the Great Lakes, especially on the United States side (which
is usually leeward, where most lake-effect snow falls) are peppered with cities
and industrial complexes, so there are millions of people in the affected region.
Second, the Great Lakes have been getting warmer because of industrial heat pol-
lution. This warmth has made the lakes better “food” for the snow-hungry winds
that sweep down from Canada during the winter. Ironically, some of the cities
most responsible for the heat pollution are the hardest and most frequently hit.
MOUNTAIN SNOW
The Atlantic and the Great Lakes can produce giant snowstorms because of the
interaction among wind, water, and land, but winter has still another ingredient
for snow making: mountains. When moisture-laden air sweeps up the side of a
mountain range, the resulting snow accumulations can be hard to believe.
The Berkshires in New England, and parts of the Appalachians, are well
known for their deep snows. The ski resorts of Colorado, Utah, and other Rocky
Mountain states are also famous for their snow. But to see nature’s snow-making
machine at its finest, we must go to the Pacific Coast. A good example is Mount
Rainier, near Seattle. Another example is the Lake Tahoe region. In January,
2004, this resort area received a series of storms resulting in snow accumulations
of up to 6 m (approximately 20 ft). The same thing occurred again in 2005, and
the effect spilled past the mountains into the Carson Valley and Reno, Nevada,
where the snow depth reached more than 2 m (6 ft).
CHAPTER 7 Winter Weather
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