Weather Underground Forecast for Tuesday, December 23, 2014

An active weather pattern will develop over the central and eastern thirds of the country on Tuesday, while unsettled weather will return to the Northwest.

A strong low pressure system is forecast to move east northeastward over the Midwest. This system will usher heavy snow showers across the upper Midwest, while light to moderate snow showers will trail this system over the central and northern Plains. A cold frontal boundary associated with this system will extend south southwestward over the Mississippi Valley and the western Gulf Coast. As this cold front collides with relatively warm, muggy air from the Gulf of Mexico, strong to severe thunderstorms will develop across the central and eastern Gulf Coast, as well as the Tennessee Valley and the southern Mid-Atlantic. Severe thunderstorms will be possible over southern Louisiana, southern Mississippi, southern Alabama, southwest Georgia and the Florida Panhandle. These thunderstorms will be capable of producing large hail, dangerous straight line winds and isolated tornadoes. In addition, light to moderate rain will be possible across the southern Plains, the middle Mississippi Valley, the southern Great Lakes, the Ohio Valley and the northern Mid-Atlantic. There will also be a slight chance of rain, freezing rain and snow across New England during the late evening hours as precipitation spreads northeastward.

Meanwhile, a cold front will approach the northwestern corner of the country. Moderate to heavy rain will develop ahead of this frontal boundary over western Washington and northwest Oregon, especially during the late afternoon and evening. A mixture of freezing rain and snow showers will impact the high elevations of the Cascades and the northern Rockies. High pressure will keep weather conditions calm across the Southwest and the Great Basin.

Temperatures in the Lower 48 states Monday have ranged from a morning low of 10 degrees at Mt. Washington, N.H. to a high of 87 degrees at Immokalee Regional Airport, Fla.