Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 456 AM EDT Wed Jul 03 2013 Valid 12Z Wed Jul 03 2013 - 12Z Fri Jul 05 2013 ...The western U.S. will see some relief from the scorching heat in time for the Fourth of July holiday... ...The flash flooding threat across the eastern U.S. should be confined to the Carolinas...Southeast...and Southern Appalachians... One more day of record breaking heat is expected across the western U.S. on Wednesday. Temperatures will yet again soar into triple digits across much of the Southwest and even farther north into the valleys of the Northern Rockies and Intermountain West. However...just in time for the Fourth of July holiday...an upper trough moving inland from the Pacific should finally bring some relief from scorching heat. Temperatures will be noticeably cooler behind the associated cold front trying to press southeastward through the northwestern U.S....but really all locations across the West should see a gradual cooling trend as the upper trough helps break down the persistent ridge that has been locked in place over the Western U.S. for the past several days. In terms of precipitation...afternoon and evening convection will become more widespread across the West...especially over a large portion of New Mexico where the Storm Prediction Center is highlighting a slight risk for severe weather. A muggy airmass will remain in place over the eastern U.S. while a rich supply of moisture continues to get funneled northward between an upper trough over the Mississippi Valley and a blocking ridge out in the western Atlantic. Numerous showers and thunderstorms will again be possible from Florida to New England on Wednesday. As the strong ridge in the Atlantic builds inland over the Eastern Seaboard on Thursday...the juicy airmass...and greatest chance for storms...will gradually shift westward. Any risk of flash flooding during the short range period should be confined to the Carolinas...Southeast...and Southern Appalachians. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php