Weather Underground Forecast for Wednesday, May 02, 2012.

A low pressure system in the Upper Midwest with its warm front extending through the Ohio Valley and Mid-Atlantic will act as the main weather producer for the nation Wednesday. Widely scattered showers and thunderstorms are expected from the Upper Midwest eastward through the Great Lakes, Ohio Valley and Mid-Atlantic. There is also a risk of severe thunderstorms across parts of the Northern Central Plains into the Upper Mississippi Valley and across the southern Great Lakes and northern Mid-Atlantic. The main threat will be large hail and damaging winds and a tornado threat is anticipated for northeastern Nebraska, southern Minnesota and Iowa.

Out West, onshore flow will continue to support light to moderate rain and high elevation snow over the Pacific Northwest and portions of northern Rockies. In addition, a stationary front will aid in producing light rain and high elevation snow showers over the central Rockies and parts of the central Great Basin.

Elsewhere, rich Gulf moisture will continue to stream northward, triggering showers and thunderstorms across central Gulf States and Florida. Farther north, a low pressure system off the Northeast Coast will bring some rain showers to northern New England mainly during the first half of the day. Temperatures in the Lower 48 states Tuesday have ranged from a morning low of 23 degrees at Mt. Washington, N.H. to a high of 95 degrees at Pecos, Texas.