Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 412 PM EDT Wed Jul 03 2013 Valid 00Z Thu Jul 04 2013 - 00Z Sat Jul 06 2013 ...Cooling trend under way across the West... ...Heavy rainfall threat gradually shifts west over the eastern U.S.... A gradual cooling trend is already underway and will spread south and east from the Pacific Northwest as a well-defined upper trough moves across western Canada and the northwestern U.S., suppressing the soaring high that has dominated the region. This will allow a cold front to push south and east from the Pacific Northwest through the northern Rockies and into the northern Great Basin, returning temperatures to more seasonal norms. Further to the south, gradual cooling is expected as well, however temperatures are expected to remain at or above normal into the later part of the week. Afternoon and evening scattered storms are expected to develop both days, especially across the high terrain of the Southwest and southern Rockies. There is the possibility that some of these storms may become severe, particularly across southeastern AZ into the southern Rockies where the Storm Prediction Center has indicated a slight risk of severe thunderstorms this afternoon and evening. Across the eastern half of the U.S., sandwiched between a retreating upper high centered across the Midwest and the Bermuda high, deep southerly winds will continue to transport both tropical moisture and a series of upper level disturbances from the Gulf of Mexico to the lower Great Lakes region. This will support widespread showers and thunderstorms across the region, with heavy rains possible, particularly from the FL panhandle northward into the TN and lower OH valleys. Some of these rains may create local runoff concerns as indicated by the WPC Day 1 Excessive Rainfall Outlook. In addition to the heavy rainfall threat, the Storm Prediction Center has noted the potential for severe thunderstorms from the central Gulf Coast/FL Panhandle northward into the southern Appalachians. As the aforementioned low shifts west and the Bermuda extends its reach further into the eastern U.S., the heavy rainfall threat is expected to gradually shift to the west as well, with warm summertime temperatures, but drier conditions beginning to spread along the Eastern Seaboard. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php