Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 250 PM EDT Thu Aug 04 2016 Valid 00Z Fri Aug 05 2016 - 00Z Sun Aug 07 2016 ...Seasonal to below average temperatures for much of the western and central U.S.... ...Heavy rain and flash flooding possible for portions of the Southwest and southern and central Rockies... ...Locally heavy rains possible for portions of the Southeast and the lower Ohio and Tennessee valleys... A well-defined cold front that currently extends from central Canada back through the central U.S. Rockies is expected to continue to push east over the next couple of days -- reaching the northeastern U.S. by this weekend. Behind this front, seasonal to below normal low temperatures are expected to spread from the Rockies into the northern and central Great Plains and upper Midwest on Friday, before reaching into the Northeast on Saturday. In addition to ushering in cooler temperatures, showers and thunderstorms are expected to accompany the front. Some of these storms may be strong to severe and produce locally heavy to excessive rains, particularly across portions of the mid Mississippi valley into the upper Great Lakes Thursday afternoon and evening. Further to the southwest, a series of weak upper level disturbances moving to the northeast while interacting with monsoonal moisture are expected to produce widespread showers and thunderstorms across parts of the Southwest into the Great Basin and the southern and central Rockies. Given the ample moisture in place, these storms will have the potential to produce heavy rainfall amounts, resulting in localized flash flooding. Across the Northwest, an upper level low and its associated frontal system are expected to drop from western Canada into the Northwest on Friday, delivering cooler temperatures and the chance for showers to the Northwest and northern Rockies. Across the Southeast, in addition to afternoon and evening thunderstorms that are supported by the typical summertime heat and humidity, a lingering frontal boundary will help encourage storms from the Carolinas back into the Tennessee and lower Ohio valleys. Many of these storms are expected to be slow moving, and given the ample moisture, may produce locally heavy amounts resulting in runoff concerns. Meanwhile, a weak upper level low is expected to move near the northern Florida Gulf coast, raising the threat for organized heavy rains along the panhandle into the northern peninsula. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php