Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 327 PM EDT Sat Aug 12 2017 Valid 00Z Sun Aug 13 2017 - 00Z Tue Aug 15 2017 ...Heavy rainfall and severe thunderstorms will be an impact throughout the Plains... ...Flash flooding will be possible across the lower Mississippi Valley... ...Showers and thunderstorms are expected in the Southeast over the next few days... A strong upper level disturbance is currently moving over the southern Plains and will continue moving eastward toward the Mississippi Valley. This disturbance will give way to heavy rainfall across Oklahoma and parts of north Texas as a stationary front along the Red River Valley provides focus for the cluster of thunderstorms. The axis of heavy rainfall will slowly drift eastward overnight tonight along the stationary front. There is a moderate risk of flash flooding in addition to a slight risk for severe thunderstorms for the rest of today and into the early hours of Sunday morning for most of southern Oklahoma and small parts of northern Texas. By Sunday afternoon, the upper level disturbance slides eastward over the lower Mississippi Valley. As a result, the heavy rainfall and flash flooding threat will shift into the Ark-La-Tex region. On Sunday night and into Monday, rainfall will be possible from the Texas Panhandle to Arkansas as the front continues to stay anchored across these regions. Farther north, an upper level low will slide along the northern Plains this evening and continue moving toward the Upper Midwest, as a front at the surface pushes across the Dakotas. Thunderstorms will develop along and ahead of the front. A slight risk of severe weather and flash flooding is possible. The precipitation will continue moving into the Upper Mississippi Valley on Sunday and by Monday lighter showers will be in the Upper Great Lakes area. A cold front will push southward across the Southeast this evening and by Sunday morning will stall through the region. The front is expected to stay put for several days with copious amounts of moisture and instability in place. This will provide a very active few days for the Southeast in terms of coverage for thunderstorms--expect most of the activity to occur in the late afternoon/evening time frame. These storms are capable of producing heavy downpours which could lead to localized flooding. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php