Tuesday, December 7, 2010

[FEMA]

Homeland Security Threat Level: YELLOW (ELEVATED)

Significant National Weather

Northeast
Light to moderate snow is forecast from Maine to West Virginia beginning this morning and continuing until Wednesday. Lake effect snow will continue across the Great Lakes region through tonight with the heaviest snow, up to 12 inches, forecast for northeast Ohio, northwestern Pennsylvania and far southwest New York.
South
Temperatures will be 10 to 20 degree below average from the Mississippi Valley eastward with sub-freezing temperatures through Wednesday morning for parts of Georgia, Alabama, Florida and Louisiana. Other locations in the region will see lows in the upper 20s. Snow showers are possible in the Southern Appalachians and northern Oklahoma later today.
Midwest
Light lake-effect snow will continue over Michigan and northern Indiana through Wednesday evening.
Some light showers are possible along the Texas Gulf Coast into early Wednesday and a wintry mix of light rain and snow is expected over western Kansas.
West
Light snow will continue in the mountains of Wyoming, northern Utah and Colorado through today. Rain showers are expected along the Pacific Northwest coast through early Wednesday morning, with snow showers at the higher elevations. On Wednesday the rain will expand southward into Central California and the snow will move eastward into the Northern Rockies.
(NOAA and media sources)

Lake Effect Snow

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Areas of Pennsylvania and New York have seen extensive lake effect snow conditions over the past few days. Lake effect snow is produced when cold winds move across warmer lake water, providing energy and picking up water vapor which freezes then is deposited on the leeward shores. If the air temperature is not low enough to keep the precipitation frozen, it can fall as lake effect rain. Since the winds accompanying cold Arctic air masses from Canada generally blow from a west or northwest direction, lake effect snow falls on the east or southeast sides of the lakes. Whether an area gets a large amount of snow from lake effect is dependent on the direction and duration of the winds and the magnitude of the temperature difference between the lake water and the air.
The areas typically affected by lake effect snow are known as snowbelts. The North American snowbelts include areas near Ontario, Canada and in the United States, the populated areas near the Great Lakes. The U.S. snowbelts include portions of western New York, northeastern Ohio, northwestern and north central Indiana, and western Michigan. Lake Superior’s lake effect snow drops an average of 200 inches onto Michigan’s Upper Peninsula every year making it the snowiest non-mountainous location in continental United States.
(NOAA and media sources)
Tropical Weather Outlook

No new activity (FEMA HQ)
Earthquake Activity

No new activity (FEMA HQ)
Wildfire Update

Fire Management Assistance Grant (FMAG)
No activity.
(FEMA HQ)
Disaster Declaration Activity

No new activity (FEMA HQ)
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