Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 233 PM EDT Wed May 17 2017 Valid 00Z Thu May 18 2017 - 00Z Sat May 20 2017 ...Severe thunderstorms and flash flooding possible from the southern plains to the Upper Midwest... ...Heavy snow possible for portions of the central and northern Rockies... ...Well above average temperatures expected from the lower Great Lakes and Mid-Atlantic to the Northeast... An active weather pattern will continue across the central U.S. through Friday with a range of weather hazards expected. One wave of low pressure along the front is forecast to move northeastward across the Upper Midwest tonight, bringing showers and thunderstorms from the Upper Midwest to the Upper Great Lakes. Severe thunderstorms and flash flooding are also possible across these areas. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. A second area of low pressure is developing this afternoon along the front across the southern/central High Plains. This developing low along with a strong upper-level low crossing the Rockies will bring a period of heavy rain and mountain snow to much of the Great Basin and the central/northern Rockies through Thursday. Farther east, ahead of the developing low, showers and thunderstorms are expected to develop on Thursday, becoming more widespread Thursday afternoon and evening across the central and portions of the southern plains. Thunderstorms are expected to persist across these areas into Friday while also spreading into portions of the Midwest/Mid-Mississippi Valley. Heavy rain and severe thunderstorms will continue to pose threats across the central U.S. through Friday. Across the eastern U.S., high pressure aloft will keep conditions dry for many areas with above average temperatures. Afternoon high temperatures on Thursday are expected to be 10 to 25 degrees above average for portions of the lower Great Lakes, Mid-Atlantic, and the Northeast. Temperatures will rise into the 90s for many areas of the Mid-Atlantic and Northeast. Scattered thunderstorms will be possible for some areas Thursday into Friday as a cold front passes through the region. The front will bring an end to the hot conditions for New England on Friday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php