Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 312 PM EST Tue Feb 19 2019 Valid 00Z Wed Feb 20 2019 - 00Z Fri Feb 22 2019 ...Significant winter storm for the Mid-Atlantic region on Wednesday... ...Heavy rain will continue a threat for flooding from the Lower Mississippi Valley into the Ohio Valley... ...Heavy snow for portions of the Upper Midwest tonight/Wednesday... ...Continued cold and snowy west of the Continental Divide... A large winter storm will affect locations from the Upper Midwest to the East Coast beginning tonight. A dome of high pressure currently in place across the Great Lakes region has set the stage for wintry precipitation with temperatures near or below freezing from the Mid-Mississippi Valley to the northern Mid-Atlantic region. As an upper level system lifts through the Great Plains tonight, significant amounts of moisture will spread north and east from the Gulf of Mexico. This moisture will meet with cold air across the Upper Midwest where an area of low pressure is forecast to develop and track across the Upper Mississippi Valley on Wednesday. Widespread snowfall totals of 4-8 inches (locally higher) are expected from eastern Nebraska into eastern Minnesota and northwestern Wisconsin through the day on Wednesday. Temperatures will remain below freezing through Thursday from the Dakotas into the Upper Mississippi Valley, which translates into daytime highs generally 5 to 15 degrees below average. Meanwhile, snow will move from southwest to northeast into Ohio and the Mid-Atlantic region late tonight, changing to a wintry mix of sleet and freezing rain and eventually all rain for many. The time of changeover will occur from southwest to northeast and depend on exact location but will be delayed for locations near the central Appalachians where significant ice accumulations near 0.25 inches along with 4-8 inches of snow (locally higher) will be possible. Major cities along I-95 from Boston to Richmond will likely see some from of frozen precipitation at the onset before changing over to rain before ending Farther to the south, heavy rain is expected to continue from the Lower Mississippi Valley into portions of the Ohio Valley where an additional 1-3 inches of rain, on top of already saturated ground, can be expected through Wednesday afternoon. Flood and flash flood watches are already in effect for many of these locations. Additional heavy rain is expected to begin for some of these same locations impacted by flooding Thursday night. Out West, high temperatures will continue to run 10-20 degrees below average along and west of the Continental Divide through Thursday. Another storm system is forecast to drop south from the Pacific Northwest tonight, reaching the Southwest by Thursday morning. Additional snowfall totals of over a foot are forecast for some of the major mountain ranges extending from Washington and Oregon into Arizona and southwestern Colorado through Thursday night. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php