The Nation's Weather 08.19.09

By WEATHER UNDERGROUND (AP)

Severe weather was forecast to persist across the Central and Northeastern U.S. on Wednesday. A low pressure system moving westward along the Canadian border would continue pulling warm and moist air over the country from the Gulf of Mexico.

This was expected to create a frontal boundary including a warm front extending over the Great Lakes region and a cold front that would stretch into the Southern Plains. Wet weather popping up along this front with scattered thunderstorms developing in the Northern Plains and Upper Midwest was expected.

Rainfall amounts would remain less than a quarter of an inch in most places, with up to 1 to 2 inches likely in areas of thunderstorm development. Strong winds, hail, and periods of heavy rain have been associated with this system. Flash flooding would also continue to affect the Plains and Mississippi River Valley. Increasingly cloudy skies and a chance for showers in the Northeast and New England as the front moved eastward, were expected.

In the Southeast, scattered showers and thunderstorms were expected to continue Wednesday as a high pressure system in the Atlantic persistently pushed abundant moisture over the region. Highs would remain in the mid-90s over the Southeast and Mid-Atlantic states.

Out West, a strong ridge of high pressure hovering over the West Coast would allow for extremely hot conditions in the Southwest and Pacific Northwest. It was expected that highs would reach into the mid-90s in the north, while the deserts would reach the 100-110 range again Wednesday.

Temperatures in the Lower 48 states Tuesday ranged from a low of 30 degrees at Yellowstone, Wyo., to a high of 118 degrees at Death Valley, Calif.