Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 436 PM EDT Wed Aug 20 2014 Valid 00Z Thu Aug 21 2014 - 00Z Sat Aug 23 2014 ...Slight risk of severe thunderstorms across portions of the northern plains, Ohio Valley, and Southeast... ...Flash flooding possible across portions of the northern plains, Midwest, and Northeast... The northern half of the contiguous U.S. will be active with showers and thunderstorms during the short range forecast period as an upper-level ridge of high pressure across the lower Mississippi valley keeps the strongest upper-level flow from the central Rockies into the northern plains and Great Lakes. A slow-moving low pressure system will bring showers and thunderstorms to the Lower Great Lakes, Mid-Atlantic, and Northeast this evening. There is a slight risk of flash flooding across portions of the Northeast tonight into Thursday. A west to east oriented warm front will serve as a focus for areas of showers and thunderstorms tonight into Friday and continuing into Saturday from the northern plains and Midwest across the Ohio valley. A slight risk of flash flooding is also forecast through Thursday in these areas. Additionally, there is a slight risk of severe thunderstorms across portions of the northern plains through tonight. Please refer to the Convective Outlook products issued by the Storm Prediction Center for further details on the severe weather threat. A frontal boundary moving into the northern Rockies and northern plains Thursday into Friday will focus areas of showers and thunderstorms across portions of the northern Rockies on Thursday and northern plains on Friday. Across the Gulf Coast/Southeast, scattered showers and thunderstorms will develop -- generally during the afternoon and evening. There is a slight risk of severe thunderstorms this afternoon and evening across portions of the Southeast northward to the Ohio valley. Temperatures over the next few days will generally be above average across much of the central and eastern U.S., and near or below average across the western U.S. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php