Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 AM EDT Wed Jul 23 2025 Valid 12Z Wed Jul 23 2025 - 12Z Fri Jul 25 2025 ...Over 95 million people are under heat related warnings & advisories from the Mississippi Valley to the Northeast today through Thursday... ...Heavy rains, flash flooding & severe weather possible from the Northern & Central Plains into the Upper Mississippi Valley & Upper Great Lakes... ...Heavy rains & flash flooding also possible from the Southeast, across much of Florida, & into the Central Gulf Coast... The remainder of the week features a strengthening heat dome over the Mississippi Valley today that gradually builds east towards the East Coast by week's end. A combination of mid-upper 90s for high temperatures and humid conditions are a recipe for oppressive heat indices that range between 100-115F for many areas along and just east of the Mississippi River today. Record heat in parts of these regions are also expected, with the bulk of the record warmth coming via the overnight/morning lows as temperatures drop only into the mid-upper 70s. The NWS HeatRisk product depicts Major Impacts, and even localized Extreme Impacts, from as far south as the central Gulf Coast to as far north as northern Wisconsin. By Thursday, the footprint of searing heat moves east into the Great Lakes and Northeast. Numerous heat-related warnings and advisories are in place today across the Mississippi Valley, with Heat Advisories also out for Thursday in parts of the Great Lakes and Northeast. WPC continues to carry Key Messages for this ongoing heat wave. Please visit www.weather.gov/safety/heat for more information on tips for how to stay cool and safe when dealing with dangerously hot conditions. As the heat ridge orients itself over the Mississippi Valley today, copious amounts of moisture over the Southern Plains will stream northward into the Midwest today. This moisture source will be directed at an approaching frontal boundary and trigger widespread showers and storms from the Central Rockies to the northern Great Lakes. There are Slight Risks issued from both the Weather Prediction Center (WPC) and Storm Prediction Center (SPC) as widespread storms across the Midwest pose a threat for both flash flooding and severe weather today. By Thursday, the flash flood threat shifts south from the central Rockies on east to the Great Lakes. WPC has issued a Slight Risk (threat level 2/4) for flash flooding from central Kansas to the western shores of Lake Michigan. Farther south, a low pressure system drifting west along the Gulf Coast will utilize tropical moisture to produce torrential downpours across portions of the Southeast. The heaviest rainfall will likely occur along the central Gulf Coast and across much of Florida through Thursday. WPC has issued a Marginal Risk for much of the Southeast given the potential for localized flash flooding through Thursday. In the West, temperatures will largely be on the unseasonably cool side thanks to a meandering cut-off upper low meandering off the California coast through Thursday night. The upper low will also act as a trigger for showers and thunderstorms in pats of northern California on Thursday, particularly in the Shasta and Sierra Nevada mountain ranges. WPC has introduced a Marginal Risk (threat level 1/4) for Thursday due to the potential for localized flash flooding near burn scars and along complex terrain in these mountain ranges. Aside from the locally heavy thunderstorms in northenr California, mostly dry conditions are anticipated in the Desert Southwest, the Pacific Northwest, and along the I-95 corridor from central Virginia to southern New England. Mullinax Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php