Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 PM EDT Sat May 23 2015 Valid 00Z Sun May 24 2015 - 00Z Tue May 26 2015 ...Flash flooding possible over much of the southern plains through Sunday... ...Slight risk of severe thunderstorms for much of the southern plains and portions of the central High Plains... ...Above average temperatures expected to develop from the Ohio valley to the Mid-Atlantic and Northeast... A very active weather pattern will remain in place across the contiguous U.S. over the next couple days. A slow-moving upper-level low across the Intermountain West today will move east into the plains by Monday. Fast-moving upper-level disturbances will traverse the central U.S. ahead of this trough. At the surface, a frontal boundary will remain nearly stationary from west Texas into western Kansas through Sunday while a warm front lifts northward across the plans and Mississippi valley. Showers and thunderstorms will be widespread in the warm, moist, and unstable air mass between these two frontal boundaries across the southern and central plains through Sunday, spreading into the lower and middle Mississippi valley early Monday. Flash flooding is possible across much of the southern and central plains through Sunday as heavy rain may fall on already saturated ground. Additionally, the Storm Prediction Center is forecasting a slight risk of severe thunderstorms over much of the same areas, and also across portions of the central High Plains. Rain and thunderstorms will also spread into the Midwest by late Sunday, and into the Great Lakes Sunday night, north of the surface warm front. An additional focused area of showers and thunderstorms is expected from Wyoming into the Dakotas tonight into Sunday north of the surface low. Scattered showers and thunderstorms are also expected across much of the interior West under the influence of the upper-level trough. Temperatures will be rising across much of the eastern U.S. as high pressure at the upper-levels expands across the region. By Monday, afternoon high temperatures will be 5 to 15 degrees above average across areas from the Great Lakes and Ohio valley to the Mid-Atlantic and Northeast. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php