Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Sun Aug 25 2024 Valid 12Z Sun Aug 25 2024 - 12Z Tue Aug 27 2024 ...Record heat relents over the Southern Plains as the heat shifts northward into the central/northern Plains and Midwest... ...Severe storms and isolated flash flooding possible for the Northern Plains/Upper Midwest Sunday-Monday... ...Daily monsoonal thunderstorms continue across the Four Corners region, shifting eastward into the southern Rockies/High Plains... As the cool upper trough pushes farther inland across the western U.S., the heatwave over portions of the Southern Plains will gradually relent during the next couple of days. Meanwhile, deep southerly flow ahead of the upper trough will direct the heat farther north into the central and northern Plains today before spreading into the Midwest on Monday, then reaching into the Great Lakes on Tuesday. The area of major HeatRisk today will expand well to the north across much of the central and northern Plains into the upper Midwest. By Monday into Tuesday, extreme HeatRisk is forecast to overspread the Midwest and toward lower Michigan where maximum heat indices are forecast to reach well into the 90s to the mid-100s in the afternoon, prompting widespread heat-related advisories and warnings. Extra caution should be observed by those without effective air conditioning and anyone who must be outdoors should remain adequately hydrated. A cold front marking the leading edge of a large dome of cool air over the western U.S. will reach into the Northern Plains on Monday, bringing relief to the heat into the region. However, the cold front will also bring a period of inclement weather across the northern Plains on Monday, followed by the possibility of severe thunderstorms by Monday night into Tuesday toward the upper Midwest. This is in response to strong upper-level dynamics ahead of the upper trough interacting with a low pressure system that is forecast to form along the cold front over the northern Plains. The Storm Prediction Center highlighted an area of enhanced risk for severe weather across the northern Plains toward the upper Midwest from Monday into early Tuesday, with a chance for potentially larger hail and significant damaging winds. Some locally heavy rainfall and isolated flash flooding will also be possible. By early Tuesday, the severe weather threat is forecast to shift east into the Great Lakes with areas of heavy rain farther north from the upper Midwest to the upper Great Lakes as the low pressure system passes to the south. Across the Southwest, daily monsoonal thunderstorm chances will continue, initially focusing over the Four Corners region today before shifting east to mainly across the southern Rockies for Monday and Tuesday. Deep moisture and moderate instability will lead to some more intense thunderstorms with locally heavy downpours along with some isolated flash flooding especially for terrain sensitive areas such as burn scars. Besides the rainfall, the big story across the West the next few days will be the much below average temperatures expected behind a strong cold front. Widespread high temperatures in the 60s and 70s will be common across the Pacific Northwest, northern Rockies, Great Basin, and northern California, with near record low maximum values for some locations. Lows are dipping into the 40s and even 30s this morning for much of the interior Pacific Northwest and Great Basin where Frost Advisories are in effect in portions of Nevada. Some post-frontal showers and storms over portions of the Great Basin will expand across the northern Rockies into the northern High Plains tonight into Monday, and then across the northern Plains later on Monday into early Tuesday. Elsewhere, some showers and storms with moderate to locally heavy rainfall will be possible Monday into Tuesday over New England when a back-door upper-level wave passes over the region. Daily showers and thunderstorms will also be possible for Florida and along the Gulf Coast with a lingering frontal boundary in the region. Over the Pacific Northwest, showers associated with the next system from the Pacific are forecast to arrive Monday night into early Tuesday. Kong/Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php