Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sun Aug 25 2024 Valid 00Z Mon Aug 26 2024 - 00Z Wed Aug 28 2024 ...Dangerous heat wave intensifies over the Midwest... ...Severe storms and isolated flash flooding possible for the Northern Plains/Upper Midwest Sunday-Monday and Great Lakes Tuesday... ...Daily Monsoonal thunderstorms continue across the Four Corners region, shifting eastward into the southern Rockies/High Plains... An upper-level high building northward over the central/eastern U.S. will help to expand/intensify a dangerous heat wave over the Midwest the next couple of days. Forecast highs in the mid-90s to near 100 combined with high humidity will send heat indices into the 105-115 degree range, with widespread heat-related advisories and warnings in place. Morning lows will also remain very warm, in the mid- to upper 70s, providing little relief from the heat overnight. Numerous record-tying/breaking highs will be possible both over the Midwest as well as into portions of the Southeast on Tuesday. Those without efficient air-conditioning or who must spend time or effort outdoors will be at a heightened risk of heat-related illness. Remember to drink plenty of water and seek out relief from the heat. An approaching cold front and increased storm coverage will help to bring relief to portions of the Upper Midwest on Tuesday. While the Southern Plains will see some relief from the record heat that has plagued the region, conditions will still be Summer-time hot with highs generally in the mid-90s. Just to the northwest, a series of upper-level shortwaves traversing the building high and an approaching cold front will continue to trigger multiple rounds of showers and storms over portions of the Northern Plains and Upper Midwest. The hot temperatures and plentiful moisture ahead of the front will contribute to strong to extreme instability and the potential for severe weather, with the first round of storms expected this afternoon/evening (Sunday). The Storm Prediction Center has issued a Slight Risk of severe weather (level 2/5) for the eastern Dakotas and western Minnesota for the threat of some large hail and damaging winds. The front will slowly push southeastward on Monday. Increasing winds aloft with a stronger wave will bring greater shear, and the expectation for more widespread/potentially organized lines of storms has resulted in an Enhanced Risk (level 3/5) of severe weather from central Minnesota west through eastern South Dakota. Very large hail, widespread and potentially significant damaging winds with any organized lines of storms, and a few tornadoes will all be possible. A broader Slight Risk covers portions of the Upper Midwest and northern/central Plains for some more isolated instances of large hail and damaging winds. The stronger upper-level wave will help to weaken the upper-high over the Great Lakes on Tuesday, with increasing storm chances and a Slight Risk of severe weather, with more instances of large hail and damaging winds expected. In addition to severe weather, the plentiful moisture and high instability will lead to the chance of some more intense downpours, and these higher rain rates along with any organized/widespread storm coverage will also bring the risk of some isolated flash flooding each day. Daily Monsoonal thunderstorm chances will continue over the Four Corners region today, shifting a bit eastward further into portions of the southern Rockies and High Plains Monday-Tuesday. Some locally heavy downpours remain possible, with the threat of isolated flash flooding, especially for terrain sensitive areas along steeper hills/mountain ranges and over burn scars. Some severe storms will also be possible through this evening, with a Slight Risk over eastern Utah/western Colorado for the threat of large hail and damaging winds. Some post frontal showers and storms are expected into the northern Rockies through Monday evening as well. Temperatures over portions of the West will remain well below average following a frontal passage and under the influence of an unseasonably strong upper-trough. Forecast highs in the 70s will be common over the northern/central Rockies and eastern Great Basin. More seasonably warm temperatures will return by Tuesday with highs back up into the 80s. However, a cold front moving into the Pacific Northwest will drop highs into the 60s and 70s. Elsewhere, an upper-level wave over New England will bring some shower and storm chances through Monday evening with some moderate to locally heavy rainfall. Some severe storms will also be possible, with a Slight Risk over southern New England for the potential of some large hail and damaging winds. The passing wave will also help to keep temperatures down here compared to elsewhere in the eastern U.S., with highs in the 70s and low 80s. Daily showers and storms are also expected over Florida and along the Gulf Coast into south Texas with a lingering frontal boundary in the region and a weakness in the upper-high passing overhead. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php