Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 328 AM EDT Tue May 05 2015 Valid 12Z Tue May 05 2015 - 12Z Thu May 07 2015 ...Severe thunderstorms and flash flooding possible across portions of the southern plains... ...Above average temperatures will continue across most of the central and eastern U.S... The weather pattern will remain very active across the contiguous U.S. through the next couple days. An upper-level low will move across the Four Corners region today. Scattered showers and thunderstorms will be possible in association with this upper-level low across the Four Corners region and into the central Rockies. Snow is possible at the highest elevations of the central Rockies, but most areas will see rain. Southerly flow across the southern plains will transport moist and unstable air northward across the region, providing fuel for widespread showers and thunderstorms. The Storm Prediction Center is forecasting a slight risk of severe thunderstorms across portions of the southern plains today. Please refer to the Convective Outlooks issued by the SPC for further details on the severe weather threat. In addition to the severe weather, flash flooding will be a concern across many of the same areas as heavy rain falls on ground that has already been saturated by previous rains. On Wednesday the upper-level low will move northward into the central and northern plains as a vigorous upper-level trough moves into the Pacific Northwest. Rain and high elevation snows are expected today and tonight across the Pacific Northwest as a result. A surface low pressure system will move across the northern Intermountain West tonight and emerge into the northern plains on Wednesday. As a result, the potential for widespread shower and thunderstorms activity will largely shift to the central and northern plains on Wednesday. There will still be a potential for showers and thunderstorms across the southern plains on Wednesday, however, with a surface dry line acting as a focus. A surface frontal boundary extending from the Ohio valley to the Mid-Atlantic will keep the potential for showers and thunderstorms in place across these areas through Wednesday. A few areas of more widespread shower and thunderstorms activity are expected. The timing and placement of these will be determined by relatively weak upper-level disturbances traversing the region. Low pressure at the surface and upper-levels will drift slowly northwestward across the Bahamas today into Wednesday. Showers and thunderstorms will affect much of southern Florida today and tonight in association with this system. The most widespread showers and thunderstorm activity will be along the Atlantic coastline of South Florida. Above average temperatures will continue for most of the central and eastern U.S. over the next couple days, with high temperatures 10 to 15 degrees above average from the Great Lakes and Ohio valley to the Northeast. Below average temperatures will arrive in the West by Wednesday as the upper-level trough and surface cold front move inland. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php