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Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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729 FXUS01 KWBC 201945 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 344 PM EDT Sat Jul 20 2024 Valid 00Z Sun Jul 21 2024 - 00Z Tue Jul 23 2024 ...A break in the heat continues for much of the Heartland but dangerous heat will build across the interior Pacific Northwest this weekend and into next week... ...Scattered thunderstorms continue across the South and Southeast as monsoonal thunderstorms linger across the Four Corners region... ...Scattered thunderstorms over the central Plains today will gradually shift into the southern Plains by Monday while a cold front will bring new rounds of thunderstorms across the northern tier states... An cooler than normal air-mass that has settled in throughout much of the Heartland will stick around not only for the remainder of the weekend but into the first half of the upcoming week. After seeing some parts of the Lower Missouri River Valley registering daytime highs only in the 70s, a cold front will continue to advance south tonight through the Southern Plains. By Sunday, daytime highs in the 70s and 80s (as low as 15 to 20 degrees below normal in the southern High Plains) will be common from central New Mexico to as far east as the Middle Mississippi River Valley. Meanwhile, a stalled frontal boundary over the Mid-South is responsible for daily rounds of showers and storms. The expansive cloud cover throughout the South will keep daytime highs capped generally in the mid-upper 80s, which is several degrees below normal (lone exception is Florida and south Texas where highs will be in the 90s on Sunday). The footprint of unusually cool temperatures for late July will persist in the Southern and Central Plains through Monday. While cooler than normal temperatures envelope much of the Heartland, dangerous heat will be a mainstay in the West through early next week. The experimental HeatRisk product depicts Major to Extreme heat risks from parts of the Lower Colorado River Valley and Mojave Desert to as far north as the Snake River Plain and Columbia River Basin. Some daily record highs and warm minimum temps are likely to be broken in these areas with the interior Northwest most likely to witness the bulk of the record heat. Major HeatRisk levels return to California`s Great Valley by Monday and look to expand throughout the center of the Golden State by Tuesday. Overall, these areas can expect highs in the 90s to 100s with little relief overnight thanks to lows in the 60s and 70s. Those in affected areas should stay hydrated, limit outdoor activities, and use fans when air conditioning is not available. This stagnant weather pattern will make for a stormy southern tier of the U.S. into next week. An elongated frontal boundary will spark numerous showers and storms from the Southern Rockies and Plains to the Southeast and Mid-Atlantic through Monday. Today, SPC does have a couple Marginal Risk areas(threat level 1/5) in the Southeast and in both the Southern and Central High Plains. However, an unusually high concentration of moisture aloft is supporting a rather wide area for Excessive Rainfall potential. WPC has issued a couple Slight Risks (threat level 2/4) for parts of the southern Mid-Atlantic and in both central New Mexico and southeast Arizona. A Marginal Risk (threat level 1/4) for Excessive Rainfall include much of the Four Corners region, the central Plains, and the Southeast. This will be a common theme for both Sunday and Monday with Slight Risks posted in parts of the Southwest on Sunday and in both the Southern Rockies and Southern Plains. The Marginal Risk areas each day are expansive, encompassing much of the Southern U.S. and portions of the southern Mid-Atlantic. Lastly, a frontal system will trigger scattered showers and storms across parts of the Midwest this afternoon and Sunday. Hit-or-miss showers and storms will remain in the forecast across the Midwest and Great Lakes early next week. Mullinax Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$