Weather across America

(NATIONAL) Snow and rain chances continue across the West with accumulations expected for the mountains and northern valleys, heavy rain and the risk for scattered flash flooding for the Tennessee Valley, and widespread showers likely ahead of a cold front for the East Coast. 

Pacific moisture will continue to flow across the West as an upper-level trough moves very slowly down the West Coast. The moisture as well as associated surface frontal systems will promote widespread snow showers as well as lower elevation/valley rain across the region. The heaviest totals should remain localized to the Sierra Nevada and mountain ranges of the northern and central Rockies. Another 5-10 inches of snow will be possible overnight for the Sierra Nevada where snow totals have been measured in feet. 

However, there will still be accumulating snow for the lower elevations/valleys in the cooler air located in northern portions of the West. Winter Weather Advisories remain in effect for portions of the Pacific Northwest through the northern Great Basin and into the northern Rockies for snow totals between 1-3 inches, locally higher in the northern Rockies. Snow will taper off first for the Pacific Northwest while lasting into the day Monday further east in the northern Rockies. Temperatures will remain below normal while winds will also be a bit blustery along the front of the Rockies.

Warm, moist air will be funneled northward from the Gulf across the South following a warm front early Monday. Widespread showers and thunderstorms are likely from the Lower Mississippi Valley east through the Tennessee Valley into the southern Appalachians and Carolinas. There is a Slight Risk of Excessive Rainfall (level 2/4) currently centered on northern Alabama, south-central Tennessee, and northwest Georgia where an axis of heavier rainfall is expected as storms move roughly parallel to the slow-moving warm front. The axis of heaviest rainfall has been shifting a bit run-to-run in the guidance so the Slight Risk may still shift before Monday. 

A Marginal Risk of Excessive Rainfall (level 1/4) is in place for Tuesday as the showers are expected to taper off through the day and rainfall totals should remain lower compared to Monday. High temperatures will be running 10-20 degrees above average south of the warm front with highs in the 60s and 70s from the Southern Plains to the Southeast Monday and Tuesday. Meanwhile, to the north, bitterly cold air will spread south from Canada into the Northern Plains and Upper Midwest. Highs near the Canadian border will be in the single digits with wind chills running below zero.

Temperatures will be around average on Monday along the East Coast before a warmup ahead of a cold front on Tuesday. Highs will be in the 40s in the Interior Northeast, 50s for the coastal Northeast and Mid-Atlantic, and 60s and 70s into the Carolinas. Widespread showers will precede the front throughout the day and into the evening. A wintry mix is possible for higher elevations in the Interior Northeast and Appalachians where temperatures will be a bit colder.