Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 431 PM EDT Fri Apr 10 2020 Valid 00Z Sat Apr 11 2020 - 00Z Mon Apr 13 2020 ...Threat of heavy rain over southern California gradually diminishes tonight... ...Significant snowfall expected to overspread the northern and central Rockies this weekend... ...Snow and wind could spread across the northern Plains toward the upper Midwest later on Sunday... ...Threat of heavy rain and severe weather expected to expand across eastern Texas toward the Tennessee Valley through this weekend... An upper-level low that has been bringing significant rain and mountain snow across the southwestern U.S. will finally lose its grip over the region as it begins to track eastward along the Mexican border tonight. Southern California will continue to be under the threat of heavy rain through tonight before the rain finally lets up Saturday morning. As the upper low weakens and spreads scattered precipitation eastward across Arizona on Saturday, our attention will be drawn farther north over the northern Rockies where a surge of cold Canadian air will arrive behind a cold front. Rain developing Friday night over Montana is forecast to expand in coverage and change over to snow overnight. By Saturday evening, much of the northern Rockies into the northern High Plains will be enveloped in snow as temperatures plunge into the teens Saturday night. Meanwhile, moisture from the Gulf of Mexico will return across the southern Plains as the upper low approaches from the Desert Southwest. A low pressure system will gradually deepen over the central Plains under this pattern. Rain will develop and then expand across eastern Texas toward the lower Mississippi Valley on Saturday along with an increasing threat of strong to severe thunderstorms. Farther north rain will also expand across the central Plains into the Midwest on Saturday as the cold front approaches from the north. The cold air mass from the north will begin to interact with the upper low in the South as well as moisture streaming up from the Gulf of Mexico to result in a rapidly intensifying low pressure system over the central Plains on Sunday. Widespread snow is expected to fall across Wyoming into much of Colorado and should begin to spread across the central Plains Sunday morning. Northerly winds are also expected to strengthen in these areas as the storm intensifies. Meanwhile, rain is expected to continue expanding across the Mississippi Valley into the Ohio Valley as the severe weather threat across much of the Deep South continues to increase. By Sunday evening, Tennessee Valley could be under a high threat of heavy rain along with severe weather. Meanwhile, snow and increasing winds could be spreading into the upper Midwest when the already impressive low pressure system continues to intensify and expand its influence across much of the central to eastern U.S. In addition, well above normal temperatures will surge up the Eastern Seaboard on Sunday in stark contrast with much below normal temperatures over the northern Plains into the Rockies. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php