Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EDT Sat Sep 20 2025 Valid 12Z Sat Sep 20 2025 - 12Z Mon Sep 22 2025 ...Scattered to widespread storms continue into the weekend from the Midwest to the central/southern Plains with isolated flash flooding possible... ...Above average temperatures for the last weekend of Summer across much of the eastern and southern U.S... ...Scattered storms return to the Southwest Sunday with an isolated risk of flash flooding... A slow-moving upper-level trough and associated surface frontal boundaries will continue to help support scattered to widespread showers and thunderstorms across much of the Midwest and central/southern Plains this weekend. Upper-level shortwaves rounding the trough will lead to multiple rounds of storms, with moisture supportive of moderate to locally heavy rainfall. The greatest concentration of storms/heavy rainfall and a risk for isolated flash flooding is expected over eastern Wisconsin/northern Illinois and from portions of the Ozarks southwest through central/southwestern Oklahoma Saturday, and the Middle Mississippi Valley west into eastern Kansas/northeastern Oklahoma Sunday. Additional more scattered storms are forecast ahead of the upper-trough across the Appalachians, Southeast, and Gulf Coast. An upper-level shortwave is expected to bring more widespread storms to portions of the central Appalachians in West Virginia Saturday, with isolated flash flooding possible here as well. To the west, a lingering upper-wave will bring some widely scattered storms to portions of the Great Basin, central/southern Rockies, and the Southwest on Saturday. Then, on Sunday, another upper-trough approaching from the Pacific will bring a return of increased Monsoonal moisture into the Southwest, with scattered thunderstorms and the risk of isolated flash flooding, particularly across Arizona. Further north, another Pacific system moving into the Pacific Northwest with bring increasing showers and some thunderstorms to the Pacific Northwest Saturday and into the northern Rockies Sunday. Much of the eastern and southern U.S. will continue to see above average and hot temperatures for the last weekend of the Summer. Highs in the upper-80s to mid-90s will be common across the Ohio/Tennessee and Middle/Lower Mississippi Valleys, the Southeast, and the southern Plains/Texas. Highs will be cooler and around or below average north of frontal boundaries across the northern/central Plains, Upper Great Lakes, and the Interior Northeast/New England, with highs in the 60s and 70s. Another round of lows dipping into the upper-20s to mid-30s for the Interior Northeast Sunday morning has prompted a second night of Frost/Freeze related Warnings and Advisories. Cooler air pushing southward east of the Appalachians will also keep more mild temperatures in the forecast for much of the Mid-Atlantic, with highs mainly in the 70s. In the West, highs will also be well above average Saturday across the Pacific Northwest and northern Rockies, with temperatures well into the 80s. A Pacific system will bring much cooler, below average temperatures to the Pacific Northwest on Sunday, as highs fall into the 60s to low 70s. Highs will generally be around or a bit below average across the central/southern Rockies, Southwest, Great Basin, and California, with highs in the 70s and 80s, and 90s to low 100s for the Deserts. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php