Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 AM EDT Wed Mar 25 2015 Valid 12Z Wed Mar 25 2015 - 12Z Fri Mar 27 2015 ...Severe weather and flash flooding are possible across areas of the Southern Plains and Ozarks... ...Wintry precipitation is likely over the Great Lakes and interior Northeast... ...Temperatures 10 to 20 degrees below normal are expected behind a strong cold front... An upper pattern which initially consisted of a series of low-amplitude systems will transition into a much more amplified setup. A broad upper trough will take shape across the center of the country and advance eastward carrying a threat for heavy precipitation, flash flooding, and much colder temperatures. The lead impulse currently moving through western Illinois is spreading an expansive shield of precipitation into the Upper Great Lakes region. Surface temperatures remain cold enough along the northern extent to support snow and freezing rain as the dominant precipitation types. All of this activity will lift northward in time as the trough gains additional latitude. The WPC winter weather forecast suggests 2 to 4 inches of snowfall is likely in the vicinity of Lake Superior while icing is expected across much of the Great Lakes region. Looking farther west, a strong lobe of energy sinking southward across the Northern/Central Rockies will be a key player in the expected severe weather and heavy rainfall over the Southern Plains and Ozarks. As this impulse moves toward Oklahoma, lift begins to increase significantly along the slow-moving frontal zone. Any convection that does develop should fire in the late afternoon to early evening hours on Wednesday with some of these storms becoming severe in nature. The Storm Prediction Center is advertising a fairly extensive region of severe development stretching from the Red River through much of eastern Oklahoma and into Ozarks. Their outlook suggests the initial storms that develop across the region may produce large hail. Moving toward the evening onward, the threat shifts toward flash flooding as rainfall rates really begin to pick up. The combination of these high rates combined with potential repeat convection will increase the threat for flash flooding anywhere from eastern Oklahoma east-northeastward into southern Indiana through Thursday morning. While this system will generally be mild in nature, the northern extent of the axis of precipitation should support snow and ice accumulations. Areas which can expect wintry precipitation include the Upper Ohio Valley, Lower Great Lakes, along with the interior Northeastern U.S. 2 to 4 inches of snow appears likely over these areas with higher amounts possible across the higher terrain of New England. Besides being a rather efficient precipitation producer, the advancing cold front will drive a fairly significant temperature gradient south and east. In the warm sector ahead of the cold front, high temperatures will soar into the 70s on Wednesday across the Tennessee and Ohio Valleys. Readings should drop 20 to 30 degrees once the front clears the region bringing temperatures to below normal for late March. Meanwhile, well above normal temperatures are likely across the western third of the U.S. as a ridge builds overhead. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php