Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 203 AM EST Wed Feb 20 2019 Valid 12Z Wed Feb 20 2019 - 12Z Fri Feb 22 2019 ...Heavy rain and wintry weather will affect much of the eastern U.S. through Thursday and additional snow expected out West... A low pressure system originating from the Gulf of Mexico is gathering strength and lifting northward towards the Ohio Valley and Great Lakes. This is in response to an upper level trough and strong shortwave impulse tracking across the Plains and Upper Midwest. Moisture is surging north from Louisiana to the Ohio Valley and central Appalachians, and heavy rain and some thunderstorms will continue in the warm sector of the low. Rainfall amounts on the order of 1 to 3 inches are expected through Friday morning across much of the Deep South as multiple rounds of rain fall over the same areas, and widespread flash flood watches are in effect. River flooding in the coming days will also be an issue. Farther to the north in a colder airmass, snow will be prevalent across the northern Mid-Atlantic region Wednesday morning with several inches of accumulation likely. With strong warm air advection aloft expected during the afternoon and evening hours, a transition to sleet and then rain is expected for areas near and east of Interstate 95. Freezing rain is also likely farther inland across western Virginia, West Virginia, western Maryland, and into Pennsylvania since the low level sub-freezing temperatures will be slower to erode for those areas. Significant icing is also possible for some interior valley locations through Wednesday evening. 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. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php