Weather Underground Forecast for Wednesday, September 05, 2012.
There are two main weather systems expected to impact the nation Wednesday. The first one is the persistent trough of low pressure extending from the Northeast to the Gulf States. This system will continue to generate widespread precipitation across the East Coast Wednesday. Heavy rain will be likely over the Northeast. This system will slowly lift northeast and depart New England by Thursday. Thus, a brief period of dry weather is expected late Wednesday to Thursday morning before the next system arrives. The Mid-Atlantic and Southeast, however, will see precipitation continuing into Thursday.
The second system is the cold front over the Upper Midwest, which will continue to move southeast, reaching the Ohio Valley and Southern Plains by Thursday morning. This front will bring an expansive area of precipitation along its path. In particular, a slight risk of severe thunderstorms is anticipated from the Great Lakes to the Mid-Mississippi Valley, mainly during the afternoon and evening hours.
Elsewhere, moist monsoonal flow will continue to support showers and thunderstorms over parts of the Southwest and Southern Rockies Wednesday afternoon and evening. Farther north, some light rain is possible over portions of the Northern High Plains late Wednesday and Thursday morning. Temperatures in the Lower 48 states Tuesday have ranged from a morning low of 26 degrees at West Yellowstone, Mont. to a high of 105 degrees at Poteau, Okla.