Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EDT Tue Jul 02 2013 Valid 00Z Wed Jul 03 2013 - 00Z Fri Jul 05 2013 ...Intense heat wave continues across much of the West with some relief in sight for the Pacific Northwest... ...Flash flooding will remain possible within a very moist airmass in place over the eastern U.S... The rather stagnant weather pattern that has been in place across the contiguous U.S. will not change appreciably through the short range forecast period. The upper-level low across the U.S. is blocked with strong upper-level ridge of high pressure across the West and a deep trough/upper-level closed low over the eastern half of the nation. Over the next few days the ridge over the West will weaken somewhat and allow some cooler flow off the Pacific to move into the northwestern States. The hot conditions will remain in place for the Southwest, albeit not quite as hot as in recent days, as the ridge weakens a little. Isolated to scattered showers and thunderstorms will be possible each afternoon across much of the West. The aforementioned upper-level low/trough over portions of the central and eastern states will drift slowly westward through the short range forecast period. This will allow the subtropical ridge from the Atlantic to build into the East Coast states over the next couple days. As a result, the trajectory of the greatest moisture and most widespread showers and thunderstorms will also shift westward. The most widespread showers and thunderstorms on Thursday will be from the central Gulf Coast northward into the Ohio River valley. Due to the south to north trajectory of the showers and thunderstorms tracking over the same areas, there is a slight risk of excessive rainfall/flash flooding across much of the Southeast through Wednesday. In addition, as the ridge builds in, temperatures will begin to rise across the Mid-Atlantic and Northeast regions. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php