Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 PM EDT Sat Jul 22 2017 Valid 00Z Sun Jul 23 2017 - 00Z Tue Jul 25 2017 ...Flash flooding and severe weather will be possible over portions of Mid-Atlantic states this weekend... ...Dangerous heat is expected to continue for the central Plains and Middle Mississippi Valley to the Mid-Atlantic coast through the weekend... ...Localized flooding possible across the Southwest and southern and central Rockies over the next few days... A wavy frontal boundary stretching from the Mid-Atlantic westward into the central Plains will continue to be the primary focus for showers and thunderstorms during the weekend. With copious amounts of moisture along with instability in place, showers and thunderstorms will occur near this boundary from the Ohio Valley to the Mid-Atlantic on Saturday and Sunday. Flash flooding will be a concern on Saturday for the Mid-Atlantic region. In addition, severe weather will also be a possibility for the Ohio Valley and Mid-Atlantic this the weekend. Strong to severe thunderstorms will also be possible for the Great Lakes region as an amplified short wave skirts eastward from the Upper Midwest to the interior of New England on Sunday. The dangerous heat that has plagued the central Plains, Mississippi Valley and the Mid-Atlantic region is expected to continue through the rest of the weekend. Heat indices reaching well over the century mark and in some cases the heat index values climbing up to 115 degrees are expected mostly in the central Plains to Middle Mississippi Valley on Sunday. Areas across the Mid-Atlantic and Carolinas will also continue to experience this oppressive heat on Sunday and into Monday. Relief from this heat will be delivered by Sunday across the Plains and Mississippi Valley as the wavy front sinks southward on Saturday night. However, relief from the heat for the Mid-Atlantic will be occur after Monday as the cold front moves over the region by Monday evening. Monsoonal moisture along with daytime heating will trigger thunderstorms across the Southwest and the southern half of the Rockies during the short term period. Heavy downpours associated with these thunderstorms could lead to localized flash flooding. Elsewhere, typical afternoon and early evening thunderstorms will occur throughout the Gulf Coast this weekend. By Monday, widespread thunderstorms associated with the cold front moving toward the Tennessee Valley can be expected. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php