Updated

Wet weather and flooding will persist Friday across the lower Mississippi River valley and the Southeast as tropical depression Isaac trek northward from the Gulf of Mexico. The center of Isaac is expected to slowly move northward over Arkansas and into Missouri.

Isaac's broad storm system will produce heavy rains from eastern Oklahoma through the lower Ohio River Valley even though it is expected to weaken as it moves further inland. Despite the loss of energy, Isaac will continue producing strong thunderstorms, heavy rain and flooding in its path.

Elsewhere, a low pressure system will push a weak frontal boundary eastward from the upper Midwest over the Great Lakes and into the Northeast. Showers and thunderstorms will be few and widespread. When this system reaches the Northeast, it will pull moisture in from the Atlantic, producing stronger showers and thunderstorms. There is a slight chance some of the storms will turn severe from northern New York state through Maine.

Out West, weak monsoonal moisture over the Southwest and southern Rockies will trigger some showers and thunderstorms Friday afternoon and evening. A high pressure area over the West Coast will maintain sunny and dry conditions for California and the Pacific Northwest.

Temperatures in the lower 48 states ranged Thurdsay from a morning low of 26 degrees at Stanley, Idaho, to a high of 105 at Corpus Christi, Texas.

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Online:

Weather Underground: http://www.wunderground.com

National Weather Service: http://iwin.nws.noaa.gov

Intellicast: http://www.intellicast.com