Weather Underground Forecast for Monday, September 30, 2013.
A pair of slow moving cold fronts will continue to drive wet weather into the Pacific Northwest on Monday, while a high pressure system will keep conditions dry along the Eastern Seaboard.
An onshore flow along the coast of the Pacific Northwest will continue to fuel showers and thunderstorms in the northwestern corner of the country. The heaviest rain will occur along the western facing slopes of the Cascades and the northern Rockies. Due to how slow these systems are moving, parts of Washington and northern Oregon will be vulnerable to flash flooding through Monday. Meanwhile, the Southwest will avoid wet weather as warm, dry conditions are expected throughout the day. The Midwest will also experience dry conditions on Monday as a ridge of high pressure sets up over Nebraska.
A stationary front stretching from the western Gulf Coast to the Ohio River Valley will lose steam on Monday as it inches eastward. A high pressure system off of the Eastern Seaboard will help weaken this frontal boundary, although moisture is still expected to accompany the front. Rain will likely move through the Ohio River Valley, and thunderstorms will set up over eastern Texas, Louisiana, Arkansas, and Mississippi. Rain will move into the Mid-Atlantic states late Monday, but the majority of the East Coast will avoid precipitation as a ridge of high pressure continues to draw cool, dry weather onshore. .
Temperatures in the Lower 48 states Sunday have ranged from a morning low of 24 degrees at Kremmling, Colo. to a high of 90 degrees at Palm Springs, Calif.