This NOAA satellite image taken Wednesday, September 21, 2011 at 01:45 PM EDT shows a swirl of clouds over the northern U.S., highlighting a low pressure system centered over northern Wisconsin, the ... more 
This NOAA satellite image taken Wednesday, September 21, 2011 at 01:45 PM EDT shows a swirl of clouds over the northern U.S., highlighting a low pressure system centered over northern Wisconsin, the Upper Peninsula of Michigan, and Lake Superior. Light showers with periods of moderate rainfall form in these areas due to this system. Meanwhile, more active weather develops near an associated warm front that extends across the Upper and Lower Great Lakes and ahead of an associated cold front that reaches across the Upper Great Lakes, through the Ohio Valley and the Mississippi Valley, into the Southern Plains. Moisture surging in from the Gulf of Mexico interacts with these disturbances to produce areas of scattered showers and thunderstorms from the Ohio Valley through the Tennessee Valley and the Central Appalachians. Moisture spreading across the central and eastern Gulf Coast also aids in producing generally light showers and thunderstorms from the Florida Panhandle through parts of Georgia and into the southern Mid-Atlantic. A wave of energy in the southern Mid-Atlantic enhances precipitation development in the Carolinas and Virgina, leading to periods of heavy rainfall and a few Flood Advisories. Elsewhere, an unstable airmass over the Central Plain triggers light showers in parts of southwestern Missouri and central and eastern Kansas. (AP PHOTO/WEATHER UNDERGROUND) less 
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Associated Press
Wed, Sep 21, 2011 2:48 PM EDT