Weather across America

(NATIONAL) Lake-effect snow downwind from Great Lakes, snow for higher elevations of the Northwest and the Upper Great Lakes, and temperatures will be 20 to 35 degrees below average over the Northern High Plains. 

Upper-level energy over the Great Lakes/Northeast slowly moves off the East Coast by Tuesday. The energy and cold air passing over the ice-free Lakes will produce lake-effect snow downwind from the Great Lakes through Monday. The lake-effect snow will be the heaviest downwind from Lakes Ontario and Erie. However, the lake-effect snow will linger longer over the eastern lakes on Tuesday.

Meanwhile, weak onshore flow will aid in producing coastal rain and higher-elevation snow over parts of the Pacific Northwest through Tuesday. Farther inland, snow will develop over parts of the Northern Intermountain Region through Tuesday.

Very cold high pressure over Alaska and Northwestern Canada will stream very cold air out of West-Central Canada into the Northern High Plains/Northern Plains that will be 20 to 35 degrees below average.

Moisture from the Western Gulf of Mexico streams northward over the Southern Plains. As a result, the atmosphere will slowly moisten, producing scattered showers and thunderstorms over the Western and Central Gulf Coast from late Sunday into Monday.

Additionally, the moisture will interact with the cold air moving southward over the Plains producing a wave of low pressure over the Central Plains Sunday night into Monday. The system will produce light snow over parts of the Northern/Central Plains and the Upper/Middle Mississippi Valley Sunday night into Monday. The low will move northward into the Upper Great Lakes overnight Monday into Tuesday, producing light snow over the region. 

On Monday, the gulf moisture will move eastward over the Southeast, producing scattered showers and thunderstorms.