Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Jul 17 2017 Valid 00Z Tue Jul 18 2017 - 00Z Thu Jul 20 2017 ...There is a slight risk of severe thunderstorms over parts of the Northeast and the Upper Mississippi Valley... ...Heavy rain possible over parts of Arizona and the Northeast today and for the Upper Midwest Tue/Wed... Scattered showers and thudnerstorms will persist along the Gulf coast states and the Southeast over the next few days. Daytime heating and upper-level impulses will interact with the very moist airmass to generate the convection, especially during the afternoon and evening hours. Monsoonal moisture streaming into the Desert Southwest combined with daytime heating and upper-level energy will trigger showers and thunderstorms over portions of the Southwest, Great Basin, Four Corners and the Southern/Central Rockies. Periods of heavy rainfall may occur, which could lead to rapid runoff and flooding. Showers and thunderstorms are forecast through midweek from the Mid-Atlantic to New England along two nearly stationary/weakening fronts. Embedded heavy rain with be possible across the Northeast through the overnight hours which will increase the risk for flash flooding. A front extending from the Lower Great Lakes/Ohio Valley northwestward into the Middle Missouri Valley will be quasi-stationary and slowly start to dissipate by Tuesday evening. In the meantime, a front extending from the Northern Plains into parts of the Great Basin will slowly move eastward to the Upper Great Lakes/Upper Mississippi Valley southwestward to parts of the Middle Missouri Valley by Tuesday. Showers and thunderstorms will develop along and ahead of the boundary over parts of the Northern Plains into Great Basin that will likewise move into the Upper Great Lakes/Middle Missouri Valley and the Northern Plains by Tuesday evening. Campbell/Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php