Weather across America

(NATIONAL) A snowy weather pattern continues in the interior mountains of the northwestern U.S. and down into the Sierra Nevada, accumulating snowfall near the Canadian border of the Northern Plains is expected to taper off, another coastal storm is forecast to bring a new round of rain up the Atlantic coast, and much above average, spring-like temperatures are shifting from the Plains/Midwest into the Northeast with a persisting Critical Fire Weather threat.

As the main energy associated with the latest winter storm that impacted the western U.S. moves off into the northern Plains, the intensity of the snow and high winds along the Sierra Nevada as well as across the Intermountain West will gradually wane through Monday. However, reinforcing upper-level energies arriving from the Pacific will keep the unstable cold air mass in place across a large section of the western U.S., with frequent rounds of mountain snows continuing and reaching as far east as the central Rockies.

From later on Monday into Tuesday, another influx of moisture from the next Pacific frontal system is expected to bring a renewed round of enhanced rainfall from northwestern California to southwestern Oregon where some locally heavy rainfall may occur. Some embedded thunderstorms could also reach farther north along the coast of the Pacific Northwest and northern California on Monday as added instability associated with a surface trough edges toward the coast. The moisture will then penetrate inland, reaching into the northern Rockies as a round of moderate to locally heavy mountain snows on Tuesday. 

Meanwhile, an intensifying low-pressure system is bringing a round of accumulating snowfall near the Canadian border of North Dakota with a wintry mix farther east across northern Minnesota on Sunday. The precipitation will taper off later tonight as the storm moves farther away into southern Canada. To the south and east, the recent dry spell will initially limit rainfall amounts along a wavy front trailing southwest toward a developing low-pressure system over the central High Plains.  However, persistent southerly flow from the Gulf of Mexico will eventually direct moisture northward to expand an area of rain from the Midwest to the Great Lakes later on Monday into Tuesday.  

An upper-level disturbance will begin to interact with the returning Gulf moisture to bring an emerging threat of heavy rain into the central Gulf Coast states on Tuesday and especially by Tuesday evening.  Along the East Coast, following a recent round of widespread enhanced rainfall, another coastal low-pressure system is forecast to form along the stalled front and track up the Mid-Atlantic coast Monday into Tuesday. This relatively compact system is forecast to deliver another round of enhanced rainfall up the Mid-Atlantic states Monday and Tuesday, reaching into New England by Tuesday afternoon.  

Across Florida, thunderstorm chances are forecast to decrease as the lingering front weakens with time but they will increase again later on Tuesday as the aforementioned upper-level disturbance begins to approach from the west. Widespread much above average, Spring-like high temperatures will persist across the central/eastern U.S. into Monday. The greatest anomalies of 25-35 degrees over the lower/mid-Missouri Valley northeastward into the upper Great Lakes on Sunday will shift into the Ohio Valley, lower Great Lakes, and interior Northeast on Monday. 

Numerous daily record-tying/breaking highs are possible as temperatures reach into the 70s for most locations. Across the central and southern Plains, persistently dry conditions accompanied by lee troughing and gusty winds will continue the threat of wildfires in the nearby High Plains at least through Sunday night into early Monday. Along the East Coast, highs are forecast to range between the 40s and 50s for New England, 50s and 60s for the Mid-Atlantic, and 70s to low 80s for the Southeast/Florida. 

In the West, highs will remain cooler and below average, ranging from the 30s and 40s in the Pacific Northwest and much of the Interior West, 50s in northern/central California, 60s in southern California, and 60s and 70s into the Desert Southwest. The coldest spot in the country will be in the northern Rockies/adjacent High Plains, where highs will be in the teens and 20s following a couple cold front passages.