Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 256 PM EST Fri Jan 18 2019 Valid 00Z Sat Jan 19 2019 - 00Z Mon Jan 21 2019 ...Major winter storm expected to move rapidly across the Midwest into the Northeast this weekend... ...Severe weather and flash flooding are possible in the Southeast... ...Heavy rain likely for the Pacific Northwest into California this weekend, with heavy snow in higher elevations of the Northwest... A surface low pressure system is strengthening across the Plains today, and is forecast to move eastward across the Mississippi and Tennessee Valleys on Saturday and northeastward across the Northeast coast on Sunday. North and west of the low, widespread winter weather is expected, and a major winter storm is on tap from the Midwest to parts of the Ohio Valley and the Northeast. 6 to 10 inches of snow is forecast for parts of the Midwest, but the highest snow totals are expected for the interior Northeast, where 1 to 2 feet of snow is forecast. Along the transition zone between rain and snow, sleet and freezing rain are possible for portions of the Ohio Valley into the Mid-Atlantic region and the Northeast coast. Strong winds are likely as well, with a tight pressure gradient between the surface low and an Arctic high pushing into the Plains. The high will cause very cold temperatures behind the low system. Temperatures that are 15 to 25 degrees below average are forecast for the Plains into the Mississippi Valley on Saturday, and these much below normal temperatures will shift into the Ohio Valley and Lower Great Lakes region on Sunday. Farther south, rain and thunderstorms are likely for the Southern Plains and Lower Mississippi Valley on Friday night, shifting eastward into the Southeast and Tennessee Valley on Saturday, as Gulf moisture streams into the warm sector. A Slight Risk of severe weather is forecast for portions of the Central Gulf Coast states, and a Slight Risk of flash flooding is in place for parts of the Tennessee Valley and Southern Appalachians on Saturday. In the West, a strong surface low pressure system will approach western Canada Friday night, with another low moving into the Northwest by Sunday morning. An influx of moisture will focus into Oregon and California, creating the potential for heavy rain there. A Marginal Risk of excessive rainfall is in effect through Friday night, increasing to a Slight Risk on Saturday near the Oregon/California border. In the higher elevations of the Cascades, snowfall totals of 4 to 8 inches are expected through Sunday evening, with higher snowfall totals of 8 to 12 inches are possible in the Northern Rockies region. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php