Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 345 PM EDT Tue Mar 17 2020 Valid 00Z Wed Mar 18 2020 - 00Z Fri Mar 20 2020 ...Snow spreads from the Intermountain West across the north-central U.S. over the next couple of days... ...Severe weather and flash flooding forecast for the Southern Plains and Lower Mississippi Valley through Wednesday... ...Colder western regions, May-like temperatures arrive in eastern regions late week... An anomalously strong upper-level low is forecast to sit over California through midweek, while upper-level disturbances moves eastward over the Four Corners late Wednesday. This will generate precipitation across the Intermountain West over the next couple of days. Higher elevations of northern California and northwestern Nevada could see an additional foot of snow through tonight. Look for snow levels to drop across the Southwest in wake of a passing cold front, bringing snow to the Mogollon Rim as well as to the Wasatch and Central Rockies through Wednesday night. Snow totals across these areas will average 6 to 12 inches with the highest totals approaching 2 feet in the highest elevations. By Thursday, periods of snow will overspread the central High Plains where disruptive snowfall accumulations of 4 to 6 inches are possible. Blizzard Warnings have been issued for western Nebraska and southeastern Wyoming on Thursday because of a developing low pressure system to the south and strong Canadian high pressure to the north generating strong northeasterly winds. This should lead to drifting snow and whiteout conditions in these areas . Ahead of the upper-level disturbance, Gulf of Mexico moisture is expected interact with a warm front that is forecast to gradually lift northward across the Southern Plains and into the Mid-South on Wednesday. Scattered showers and thunderstorms are possible all around these areas, but the area with the greatest threats from the storms today and Wednesday will be the Southern Plains. Slight to Enhanced Risks of severe thunderstorms are in place along with Slight Risks for excessive rainfall/flash flooding for much of the Southern Plains today and Wednesday. By Wednesday, rainfall amounts over an inch in the Ohio Valley could lead to flash flooding as well. Due to the slow progression of the longwave upper-level trough over the West Coast, expect the Lower and Middle Mississippi Valleys to become most at risk for severe storms and heavy rain on Thursday. Temperature wise, the upper low will help force temperatures to fall 10 to 20 degrees below normal across California into the Central Great Basin and Southwest. By Thursday, a cold front will usher in much colder temperatures to the High Plains. While the West trends colder, eastern and southern regions will bask in May-like temperatures the second half of the week. The Gulf Coast states will remain quite warm through the week but look for the Southern Plains to trend colder by Friday. Abnormally warm temperatures will arrive in the Midwest and the Mid-South tomorrow then reach the East Coast by Thursday. By Friday, some portions of the Northeast and Mid-Atlantic will have a chance to hit 80 degrees for the first time this year. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php