Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 412 PM EDT Thu Jul 18 2024 Valid 00Z Fri Jul 19 2024 - 00Z Sun Jul 21 2024 ...Dangerous heat to expand across the Western U.S this weekend... ...Multiple areas of unsettled weather from the Four Corners to Upper Midwest; Southeast to Mid-Atlantic... The main headline for the Nation's weather story this afternoon remains dangerous heat expected to build across the Western U.S this weekend, where 38 million people are under heat alerts from the interior Pacific Northwest to the Desert Southwest and California. As an upper-level ridge amplifies tomorrow, daily high temperatures will begin the climb in the 90s and triple-digits, with little overnight relief expected. These brutal temperatures could challenge numerous records across the region beginning this weekend, ultimately leading to dangerous conditions as the heat looks to stick around beyond this weekend. Meanwhile, monsoonal showers and thunderstorms will continue through this weekend east of the Four Corners region, which will bleed into the High Plains and Upper-Midwest as some monsoonal moisture and disturbances drive additional thunderstorms along and ahead of a lee-side trough. Not to be outdone, a lingering frontal boundary forecast to meander northward will also force daily thunderstorms across the Southeast and Mid-Atlantic. As is usually the case this time of year, isolated to scattered flash flooding and severe weather may result from the strongest storms owing to the copious moisture and instability available. Asherman Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php