Weather Underground Forecast for Monday, September 19, 2011.
Active weather will continue in the nation 1/4's mid-section on Monday as a complex frontal system moves eastward through the Mississippi Valleys and into the Upper Great Lakes and the Eastern Valleys. Energy from this disturbance will interact with ample moisture spreading from the Gulf of Mexico to produce swaths of showers, periods of heavy rainfall, and thunderstorms from the Great Lakes through the Southern Plains. Areas of the Ohio, Tennessee, and Mid-Mississippi Valleys will experience the heaviest rains. Some thunderstorms may reach the western regions of New York and Pennsylvania by Monday night. Meanwhile, ahead of this activity, outside of a few showers in Florida, high pressure will provide generally dry conditions to much of the Eastern Seaboard. Temperatures in the East will range from the 60s in the Northeast to the 70s and 80s in the Mid-Atlantic. Expect highs in the 80s and 90s to persist from Texas through Florida. To the north, 60s and 70s are expected highs in the Great Lakes, while the Northern and Central Plains reach into the 70s and 80s.
In the West, showers will taper off in the Pacific Northwest as a cold front moves through the Northwest. This disturbance may kick up a few thunderstorms in Idaho and Montana as it progresses. Temperatures in the West will remain near average or slightly above average on Monday. Temperatures in the Lower 48 states Sunday have ranged from a morning low of 24 degrees at Pinedale, Wyo. to a high of 97 degrees at Edinburg, Texas