Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 405 AM EDT Tue Mar 24 2015 Valid 12Z Tue Mar 24 2015 - 12Z Thu Mar 26 2015 ...Wintry precipitation expected from North Dakota eastward to the Great Lakes... ...Severe weather is possible across the Southern Plains into the Ozarks... ...A threat for flash flooding exists over the Ozarks Wednesday evening through Thursday morning... Over the course of the period, the upper flow will gradually become more amplified in nature as a deep trough begins to encompass the center of the country. By Thursday morning a pair of ridges will set up across the Western U.S. and Western Atlantic, respectively. The overall weather pattern is expected to be active with a winter storm forecast to affect the northern tier of the country. This system will move in two parts with light snowfall accumulations expected over North Dakota into the Upper Midwest as the initial upper trough crosses the region late Tuesday night. Meanwhile, the more dynamic feature will strengthen markedly while migrating toward the Lower Great Lakes by early Wednesday morning. Moderate to heavy snows are likely just to the north and west of the surface low which will spread any where from 4 to 6 inches of snow across the Upper Great Lakes. Freezing rain is also possible across the entire Great Lakes region as milder air just above the subfreezing surface layer invades from the south. A rather potent cold front moving into the Southern Plains and Ozarks will set the stages for organized convection the next couple of days. While rainfall is expected along much of the frontal zone, it appears there will be enough instability across the aforementioned regions to promote severe thunderstorm activity. The Storm Prediction Center has this region highlighted in its convective outlook through Thursday morning given the favorable conditions for severe weather. Additionally, flash flooding is a possibility across sections of the Ozarks given heavy rainfall which may repeat over similar areas on Wednesday evening through the following morning. Wet conditions will prevail during the next couple of days across the Pacific Northwest into the Intermountain West. A series of impulses tracking across the region will help spawn a broad axis of precipitation, much of it snow across the higher elevations. The WPC winter weather desk expects the heaviest accumulations across the Tetons and Bighorns where 6 to 8 inches are likely through early Thursday. Conditions should gradually improve toward the end of the forecast period as an upper ridge builds overhead. In terms of temperatures, it should be quite warm ahead of the strong cold front moving through the center of the U.S. This is rather noticeable across much of the Tennessee and Ohio Valleys where temperatures should drop 15 to 20 degrees as cool, Canadian air works its way in from the north and west. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php