Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 818 AM EDT Sat Jul 08 2017 Valid 12Z Sat Jul 08 2017 - 12Z Mon Jul 10 2017 ...Dangerous heat continues in the Southwest this weekend... Over the western United States an upper-level ridge will remain anchored near the Four Corners regions and will cause extremely hot conditions to persist through weekend. On Friday many record high temperatures were set, including 116 degrees at Las Vegas and 122 degrees at Palm Springs, California. Excessive Heat Warnings are in effect for much of the Desert Southwest through Saturday night, with temperatures remaining even hotter than these arid or desert regions are used to experiencing. Farther north into the Great Basin and Northern Rockies, temperatures in the 90s and 100s are expected this afternoon, which is 10 to 20 degrees above average. Numerous daily temperature records may be tied or broken once again. The heat will expand eastward into the Northern Plains by Sunday. Isolated thunderstorms are expected in the interior western U.S. as well, mainly during the afternoon. Farther east, a cold front will continue to move into the Gulf states, extending northeastward through the Mid-Atlantic and Northeast. Showers and thunderstorms will form along and ahead of this front, producing periods of locally heavy rainfall. Flash flooding is possible across portions of the lower Mississippi Valley and New England today. A secondary cold front will pass through the Upper Midwest and Great Lakes region this weekend which will bring another round of showers and thunderstorms. This system will have greater potential to produce heavy rain, and flash flooding may occur over portions of the Upper/Middle Mississippi Valley on Sunday. Campbell/Tate/Burke Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php