Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 345 AM EDT Thu May 17 2018 Valid 12Z Thu May 17 2018 - 12Z Sat May 19 2018 ...A persistent wet pattern across parts of the Eastern U.S. with flash flooding possible through the end of the week... ...Severe thunderstorms and heavy rainfall possible across the portions of the Great Plains into the weekend... Numerous showers and thunderstorms will track from the south-central states through the Ohio/Tennessee Valleys and into the Mid-Atlantic region over the next few days as tropical moisture transports northward out of the Gulf of Mexico and interacts with a nearly stationary frontal boundary draped across the region. The best chance for heavy to excessive rainfall will be along the boundary from the central Appalachians to the Mid-Atlantic in association with a weak disturbance lifting northward across the Deep South. WPC has highlighted this region in a slight risk for excessive rainfall from tonight through early Friday, with a marginal risk on Saturday extending north from the Mid-Atlantic to southern New England. Another active region over the next few days will be along the Central Rockies and the adjacent High Plains. This area will have scattered to widespread convection as Gulf Moisture lifts northward and interacts with two frontal systems- one dropping south through the Northern High Plains and one lifting into the Southern/Central High Plains. Strong to severe thunderstorms are expected to develop within this region; therefore the Storm Prediction Center has identified this sector of the country as having a slight risk for severe weather. Please refer to the SPC webpage for specific details on the severe weather risk. Within these storms, heavy rainfall will likely occur. WPC has highlighted a broad area with a marginal risk for excessive rainfall, however the best area will be focused near western Nebraska on Friday and near the northeast Nebraska/southeast South Dakota border on Saturday. Meanwhile out west, active weather should continue as a weakening upper level low drifts eastward through the Great Basin and into the central Rockies. Showers and thunderstorms can be expected through the next few days across much of the Northwest, with localized enhanced activity along the favored terrain. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php