Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 409 PM EDT Fri Jul 05 2013 Valid 00Z Sat Jul 06 2013 - 00Z Mon Jul 08 2013 ...Heavy rain/flash flooding threat continues across the Southeast, Tennessee and Ohio Valleys... ...Slight risk of severe thunderstorms for portions of the Northeast today and northern Plains on Saturday... ...Above average temperatures to continue over the West... A plume of moisture originating in the tropics will continue to stream northward across the Southeast, lower Mississippi River valley, southern Appalachians, and Ohio River valley. This moisture plume will continue through the short range forecast period; although it will begin to shift eastward by Sunday as an upper-level ridge of high pressure over the Atlantic weakens somewhat, allowing the upper-level trough over the middle Mississippi River valley, and the moisture plume ahead of it, to shift eastward. Scattered to widespread showers and thunderstorms will be possible each day. Due to heavy rains in recent days over the same areas, flash flooding will continue pose a threat. On the northern extent of the moisture plume across the Northeast, there is a slight risk of severe thunderstorms through tonight. Please refer to the Convective Outlook products from the Storm Prediction Center for further information on the severe weather threat. A frontal system will move from the northern Rockies today into the northern High Plains on Saturday. As low-level southerly flow strengthens across the plains on Saturday, transporting moisture northward into the system, the threat for showers and thunderstorms will spread across the northern Plains. The Storm Prediction Center has outlined portions of the northern Plains with a slight risk of severe thunderstorms on Saturday. Elsewhere across the West, while the intense heat wave of recent days has abated to an extent, above average temperatures will continue as the upper-level ridge of high pressure responsible for the heat persists over the southwestern states. There will be the potential for isolated to scattered afternoon and evening thunderstorms across much of the West through the short range forecast period. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php