Weather Underground Forecast for Thursday, September 22, 2011.
Wet and active weather will develop in the Eastern Seaboard on Thursday as a low pressure system in Lake Superior lifts northeastward through Ontario. As this system exits, an associated cold front will reach across the Appalachians through the Deep South and into Texas. Rich moisture spreading northward from the Gulf of Mexico will interact with this front to produce good coverage of showers with periods of heavy rainfall and thunderstorms from the eastern Gulf Coast through the Southeast. Areas of scattered showers are also anticipated in the Mid-Atlantic and Northeast. Precipitation in the Mid-Atlantic and the Northeast will become more pronounced on Friday with rounds of locally heavy rainfall.
Behind this cold front, an unstable airmass will produce more showers and thunderstorms in parts of the Southern High Plains through Oklahoma and the Mid-Mississippi Valley. Expect temperatures in the Midwest to remain pretty cool as remain pretty cool for this time of year.
In the West, pockets of light showers will form in northwestern Washington as a cold front clips the Pacific Northwest. Temperatures in the Lower 48 states Wednesday have ranged from a morning low of 21 degrees at West Yellowstone, Mont. to a high of 100 degrees at Palm Springs, Calif.