Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Thu May 18 2017 Valid 12Z Thu May 18 2017 - 12Z 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... Much of the central U.S. will have scattered to numerous showers and thunderstorms through the end of the week as multiple waves move along a slow moving frontal boundary. Severe thunderstorms and heavy rainfall amounts are expected across much of the southern/central Plains and Midwest. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. Heavy rain and mountain snow will continue across the Great Basin and the central/northern Rockies today. Heavy rain and severe thunderstorms will continue to pose threats across the central U.S. through Friday. Much of the eastern U.S. will have mostly dry conditions as high pressure remains aloft. Many locations will have afternoon high temperatures of 10 to 25 degrees above average for portions of the lower Great Lakes, Mid-Atlantic, and the Northeast today. Temperatures will then 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. Campbell/Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php