Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 AM EDT Mon Aug 21 2017 Valid 12Z Mon Aug 21 2017 - 12Z Wed Aug 23 2017 ...Flash flooding and severe weather will be possible from the Upper Mississippi Valley to New England over the next few days... ...Heavy rainfall will continue across the Southern Rockies today... A front, which has slowed across the Upper Mississippi Valley and central Plains, will act as a focus for showers and thunderstorms over the next few days. As it stalls across the Upper Mississippi Valley and central Plains, heavy rainfall leading to flash flooding and severe weather in these regions will be possible on Monday. As the upper level trough begins to amplify and push eastward overnight Monday and into Tuesday, this will mobilize the cold front to progress south and east--as will the convection. The threat of flash flooding will shift to the Southern Plains and northward into New England. A slight risk of severe weather will also be possible for New England and the Ohio Valley. By Wednesday morning, the front will move into coastal New England through the Tennessee Valley. Expect lighter precipitation from New England through eastern Tennessee with showers and thunderstorms beginning to increase across the Southeast. Please visit the Storm Prediction Center for more detailed information on severe weather and WPC's excessive rainfall on details areas of flash flooding. An upper level disturbance in combination with monsoonal moisture will give way to heavy rainfall in the Southern Rockies and extreme western Texas area. The heavy rainfall is expected to continue through Monday morning and lighten up by the afternoon--although lingering showers and thunderstorms will be continue through the end of the day. Flash flooding will be possible on Monday and into Tuesday as some of these thunderstorms could produce heavy downpours. Farther west, a slow-moving upper low off the California coast should give way to scattered to isolated shower activity across portions of California and the Central Great Basin early this week. Heaviest rainfall can be expected in the Sierra Nevada mountain range. Elsewhere, isolated to scattered thunderstorms will be possible across the Desert Southwest each afternoon due to monsoonal moisture and daytime heating. In addition, typical afternoon thunderstorms will happen along the central and eastern Gulf Coast through the short term period. As an inverted trough pushes eastward toward the east coast of Florida on Tuesday and Wednesday, expect an increase of precipitation. Expect much cooler temperatures behind the cold front as it sweeps eastward. Meanwhile, warmer than normal temperatures will occur in the Pacific Northwest and northern Rockies. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php