Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 234 AM EDT Thu Jul 28 2016 Valid 12Z Thu Jul 28 2016 - 12Z Sat Jul 30 2016 ...Heavy rain possible from the lower Mississippi valley to the Mid-Atlantic through Friday... ...Severe thunderstorms possible today for portions of the plains and the Mid-Atlantic... ...Hot and mostly dry conditions will persist through Friday across the West... Moisture associated with an upper-level low that originated in the tropics will merge interact with a stationary frontal boundary today, bringing numerous showers and thunderstorms to areas from the lower Mississippi valley to the Mid-Atlantic. Due to the deep tropical moisture associated with this system, heavy rainfall is possible with a threat for flash flooding. Additionally, some thunderstorms may be severe today across the Mid-Atlantic region. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. The system will continue to move northeastward, spreading showers and thunderstorms into the Northeast tonight into Friday. Even after this upper-level feature passes, the surface frontal boundary will linger, and scattered showers and thunderstorms will be possible across much of the eastern U.S. into Saturday. The same frontal boundary extends west across the plains, and will focus the development of showers and thunderstorms in that region today. Across the central and southern plains, some thunderstorms may produce severe weather and heavy rainfall. As with farther east, the front will linger across the central plains into Friday and Saturday, keeping scattered showers and thunderstorms a possibility. Across the West, high pressure aloft will keep conditions hot and dry for most areas. Isolated afternoon and evening thunderstorms are possible each day across the higher terrain of the interior Southwest. High temperatures across most of the West are forecast to be 5 to 15 degrees above average today and Friday. Heat advisories and excessive heat warnings have been issued for some areas. The hot and dry conditions will exacerbate drought conditions and wildfires, in areas experiencing them. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php