Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 413 AM EDT Mon Jul 04 2016 Valid 12Z Mon Jul 04 2016 - 12Z Wed Jul 06 2016 ...Flash flooding and severe weather possible for portions of the Ohio Valley and Mid-Atlantic states on Monday... ...Persistent heat and humidity will remain the story from Texas to the Carolinas the next few days... ...Cooling trend will continue across the northwestern corner of the Nation early this week... ...The threat for heavy rains and strong to severe thunderstorms expected to increase over the Upper Mississippi Valley... Showers and thunderstorms are expected near a frontal boundary slowly surging northward through the Ohio Valley and Mid-Atlantic states on Monday. The greatest threat for any flash flooding or severe weather should be ahead of surface wave tracking northeastward along the front...where an abundance of low level moisture surging northward will feed into developing convection. By Tuesday...the chance for any widespread heavy rains or severe storms should diminish as the surface wave lifts away from the Mid-Atlantic coast. Warm and muggy will remain the story beneath an upper ridge expanding over the southern tier of the Nation the next few days. Heat advisories have been issued for portions of the southern Plains...Lower Mississippi Valley...and Carolinas...where the combination of high temperatures and dew points could result in triple digit heat indices. Enough weakness in the ridge aloft should allow for scattered shower and thunderstorm activity across the central Gulf Coast states. A cooling trend will continue for locations from the Pacific Northwest to the northern High Plains as an upper trough digs into the northwestern corner of the Country Monday and Tuesday. Also...a cold front at the leading edge of height falls could trigger showers and thunderstorms while pushing through the north central U.S. early this week...with the potential for heavy rains and strong to severe storms once the boundary reaches the Upper Mississippi Valley on Tuesday. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php