Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 435 AM EDT Thu Jul 04 2013 Valid 12Z Thu Jul 04 2013 - 12Z Sat Jul 06 2013 ...Flash flooding will be a threat from the Florida Panhandle into the Ohio Valley... ...Cool down continues out West... Showers and thunderstorms will continue to light up within a muggy airmass in place across the eastern third of the Nation. A rich supply of moisture getting pumped northward in-between a deep upper trough over the Mississippi Valley and a strong ridge in the western Atlantic will allow for some intense rainfall rates within developing storms from the Gulf Coast to the Lower Great Lakes. The heaviest rains...and greatest threat for any flash flooding...will initially be from the Florida Panhandle into areas surrounding the southern Appalachians. As the ridge in the Atlantic builds inland....the heavy rainfall threat will gradually shift westward into portions of the Tennessee and Ohio Valleys. Also...the building ridge will begin spreading drier...warmer...conditions into the Eastern Seaboard. The gradual cooling trend will continue across the western U.S. as a potent shortwave digs into the Northwest and helps break down the expansive ridge that dominated the region over the past several days. The associated surface cold front will continue to press southeastward through the Pacific Northwest...northern Great Basin...and northern Rockies...dropping temperatures back down to normal across the region. Further south...conditions will be slightly cooler than earlier in the week...but excessive heat warnings will still be in effect across portions of the Desert Southwest and into California. Scattered late afternoon/early evening convection will be possible across much of the western U.S. over the next few days...especially over the higher terrain of the central/southern Rockies and the Southwest. Weather will become increasingly unsettled across the north central U.S. heading towards the end of the week. A weak disturbance will trigger some isolated convection across the Dakotas and Upper Minnesota on Thursday. By Friday...the cold front cooling down the Northwest will begin pushing out into the Northern Plains...bringing a greater threat for some showers and thunderstorms. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php