940 FXUS02 KWBC 241959 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Wed Jun 24 2026 Valid 12Z Sat Jun 27 2026 - 12Z Wed Jul 01 2026 ***Additional heavy rain for the Midwest and Ohio Valley*** ***Heat and humidity increases across the Central and Southern U.S. starting this weekend*** ...Pattern Overview... An anomalous upper low digging into the northwestern states will put an end to the heat wave across the Southwest and even lead to some higher elevation snow for the northern Rockies. This trough will spur surface cyclogenesis across the Plains with an occluded low lifting north across south-central Canada. In contrast, a building downstream upper ridge across the east-central U.S. will result in increasing heat and humidity going into next week. Numerous showers and storms are likely from the Ohio Valley to the Northeast on Saturday to the south of a slow-moving frontal boundary. ...Guidance/Predictability Assessment... Assessment of the latest model guidance suite continues to highlight a faster eastward ejection of a shortwave from the Ohio Valley toward the Mid-Atlantic along the stationary front this weekend. Meanwhile, model consensus has continued to trend toward a higher amplitude ridge to extend northward across the Midwest from an expanding closed upper high centered over the east-central U.S. while the upper low over the Northwest U.S. lifts into southern Canada and opens into a positively-tilted trough. The stronger ridge continues to increase the chance for heat to build across the upper Midwest early next week. In addition, latest 12Z ECMWF continues the trend to increase the strength of the upper high over the Southeast U.S. which would support the chance for the heat to increase across the east-central U.S. to the Southeast toward the middle of next week. In contrast, models have trended toward lower heights to dip further south into the Great Basin with cooler temperatures than in previous forecasts. The WPC fronts/pressures were based on a general deterministic model blend for the weekend, followed by a higher percentage of the ensemble means towards the middle of next week. The NBM was a reasonable starting point for most areas of the country, although a smoother QPF field was used to replace some of the high QPF maxima and a reduction of 0.02 inch areas where it was widespread. In addition, temperatures were lowered for coastal areas of the Mid- Atlantic, Northeast, and the Great Lakes. ...Weather/Hazards Highlights... A stormy start to the weekend is forecast across the Ohio Valley and into the central Appalachians as a wave of low pressure and a shortwave aloft fuel the development of widespread showers and storms, with 1-2 inch rainfall totals likely where storms are most persistent. Another region of perturbed weather will also be likely across the Dakotas with enhanced rainfall and strong/severe thunderstorms developing near the main surface low. Both of these areas probably have an abatement in rainfall coverage and intensity by Sunday. Looking ahead to Monday/Tuesday, a corridor of showers and storms, some of which could be heavy, are forecast to develop from Nebraska to the Upper Peninsula of Michigan ahead of the cold front crossing the Upper Midwest. Elsewhere across the country, decreasing snow levels across the northern Rockies will lead to a very late season snowfall across the higher terrain of western Montana, central Idaho, and northwestern Wyoming, especially Saturday night into early Sunday, and cold rain for the valleys. Some thunderstorms may develop along the dryline across western Texas for the beginning of the week, but currently not expected to be widespread. Scattered showers and thunderstorms are expected from the central Gulf Coast to the Florida Peninsula for the first half of next week with moisture increasing south of the upper ridge. A temperature dichotomy will exist across the country starting this weekend as the deep upper trough heralds the arrival of much cooler conditions starting across the Pacific Northwest, and then the Rockies by Sunday with highs running on the order of 15-25 degrees below late June averages. This will likely be cold enough to establish some new daily record low temperatures. The opposite will hold true from the Plains to the Ohio Valley with widespread above average temperatures expected with the strong upper ridge developing. Highs in the 90s are expected as far north as the Great Lakes and Minnesota, and 100s for much of Texas. Heat indices approaching 110 degrees are possible from the Mid-South to the central Gulf Coast where the combination of heat and high dewpoints will be greatest. Overnight lows will also be quite warm, with some record high minimums possible. Kong/Hamrick Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw $$