Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Tue Aug 01 2017 Valid 00Z Wed Aug 02 2017 - 00Z Fri Aug 04 2017 ...Potentially record-breaking heat in store for the Pacific Northwest... ...Heavy rain and strong thunderstorms possible for Northern High Plains to Upper Mississippi Valley... ...Tropical Depression Emily will become Post-Tropical Cyclone Emily and is not a threat to land... An upper-level ridge in the western U.S. will lead to very hot temperatures for the Pacific Northwest in particular. High temperatures are expected to reach over 20 degrees above average there on Wednesday and Thursday, and multiple temperature records could be tied or broken. Heat will extend into much of California as well. Excessive Heat Warnings and Heat Advisories are in effect for much of the West Coast and into the Great Basin. Farther east, a frontal system stretching through the Upper Mississippi Valley, Northern Plains, and Northern Rockies will track south over the next few days, bringing showers and thunderstorms with it. Tuesday night, this front and associated low pressure system will lead to a slight risk of severe thunderstorms in the Northern High Plains, as well as the potential for heavy rain. On Wednesday, the front will sink slowly southward, and portions of the Northern Plains and Upper Mississippi Valley could see heavy rainfall that could produce flash flooding. By Thursday, the cold front will continue moving south and east into the Middle Mississippi Valley and Southern Plains, once again aiding in thunderstorm development. As moisture streams in ahead of the front, scattered showers and thunderstorms are expected in the Ohio Valley, Mid-Atlantic, and Northeast as well on Wednesday and Thursday. The southwestern U.S. will continue to see monsoonal moisture streaming in over the next few days, which will help cause showers and thunderstorms there. Areas from southwestern Arizona through western Texas could see heavy rain and the possibility of flash flooding with these thunderstorms, particularly Tuesday night. Ample moisture along the Gulf Coast will lead to showers and thunderstorms in that area over the next few days as well. Meanwhile, Tropical Depression Emily is forecast to continue moving northeastward through the western Atlantic, causing no threat to land and becoming Post-Tropical Cyclone Emily by Wednesday evening. For the most up-to-date information on Emily's track and intensity, see the latest advisory from the National Hurricane Center. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php