Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 432 AM EDT Sun Jun 30 2013 Valid 12Z Sun Jun 30 2013 - 12Z Tue Jul 02 2013 ...A stagnant weather pattern setting up over the lower 48 will allow for the scorching heat to continue in the West while stormy weather will remain the story along the Eastern Seaboard... Out West...temperatures will continue to approach or exceed records underneath an expansive upper ridge anchored over the Southwest and Great Basin. Excessive heat warnings remain in effect for a large portion of California...Nevada...and Arizona...where daytime highs will yet again dangerously soar well past the century mark and overnight lows will barely drop into the seventies and eighties. As the ridge begins to build northward late Sunday and into Monday...triple digit temperatures will expand north through the Intermountain West and all the way to the Canadian border. In terms of precipitation...the majority of the western half of the Nation will stay dry throughout the forecast period... however...weak impulses of energy sliding down the eastern edge of the upper ridge should help trigger scattered convection over the Southern and Central Rockies during the afternoon hours. In the East...an upper trough will continue to amplify as it gets squeezed between the expansive ridge over the Western U.S. and a strong ridge over the western Atlantic. The associated surface front will become rather diffuse as it stalls out near the Appalachians...but a rich supply of moisture east of boundary...combined with weak pieces of energy aloft...will allow for numerous showers and thunderstorms to fire up from Florida to New England. Although there is not a big threat for severe weather with this set up...multiple days of heavy rains could eventually lead to some flash flooding. Behind the dissipating frontal boundary...shortwave energy embedded within the amplifying upper trough will cause some scattered showers and thunderstorms over the Ohio and Tennessee Valleys. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php