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Weather Underground Forecast for Thursday, April 23, 2015

A strong low pressure system will impact the Northeast on Thursday, while an onshore flow will persist across the West Coast.

A vigorous area of low pressure will shift eastward over southeast Canada and northern New England. This system will usher moderate to heavy snow showers over northwest New England, as well as a mixture of rain and snow over the northern Mid-Atlantic and southern New England. A cold frontal boundary associated with this system will extend across the western Atlantic and the Gulf Coast. This frontal boundary will separate a relatively cold air mass and warm, muggy air over the Gulf of Mexico. As these two air masses collide, rain and thunderstorms will fire up across the Southeast, the Deep South, the southern Plains and the central Plains. Severe thunderstorms will be possible across several states, including southern Oklahoma, Texas and Louisiana. These thunderstorms will be capable of producing large hail, dangerous straight line winds and isolated tornadoes.

Meanwhile, an area of low pressure will slide across the upper Intermountain West and the northern Plains. This system will bring a light mixture of rain and snow to the central and northern Rockies, while scattered showers and isolated thunderstorms will be possible over the northern Plains.

An onshore flow from the Pacific will persist across the West Coast. Showers and stray thunderstorms are expected across the Sierra Nevada Mountain and the San Bernadino Mountains. Additionally, a cold front will approach the Pacific Northwest. Light to moderate rain will develop ahead of this frontal boundary over western Oregon and western Washington.

Temperatures in the Lower 48 states Wednesday have ranged from a morning low of 12 degrees at Tioga Municipal Airport, N.D. to a high of 88 degrees at Tampa Macdill AFB, Fla.