Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 341 AM EDT Thu Jul 02 2015 Valid 12Z Thu Jul 02 2015 - 12Z Sat Jul 04 2015 ...Severe thunderstorms and flash flooding possible from portions of the southern plains east to the southern Appalachians... ...Temperatures across the northwestern U.S. will remain well above average... The weather pattern across much of the contiguous U.S. has changed little over the past several days, and this will continue during the short range forecast period. A nearly stationary frontal boundary extending across the central/southern plains, middle Mississippi valley, Ohio valley, and southern Mid-Atlantic states will move little over the next few days. Relatively weak waves of low pressure at the surface, responses to upper-level disturbances, will traverse the frontal boundary and provide areas of focus for showers and thunderstorms. In the vicinity of this frontal boundary today and tonight, strong to severe thunderstorms as well as flash flooding are possible from portions of the southern plans eastward to the southern Appalachians. Refer to products issued by the Storm Prediction Center for further information on the severe weather threat. On Friday, the axis of best focus for showers and thunderstorms is forecast to shift slightly southward, more into portions of the lower Mississippi and Tennessee valleys. Farther north, a cold front will move southward from Canada into the Midwest and Upper Great Lakes on Friday, bringing scattered showers and thunderstorms. Across the Northeast, dry conditions will prevail through Friday, with temperatures near or slightly below average due to an upper-level trough overhead. Finally, across the West, the upper-level ridge that has been persistent for many days will further persist. There are some signs that the ridge may begin to weaken somewhat by late Friday into Saturday -- temperatures are expected to remain above average through the beginning of the weekend, however. Afternoon high temperatures today and Friday will be 10 to 20 degrees above average across the northwestern U.S. As has been the case in recent days, scattered afternoon and evening showers and thunderstorms are possible farther south from the Sierras eastward to the Four Corners region. These showers and thunderstorms will be focused primarily in areas of terrain. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php