Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 351 AM EDT Sun Sep 01 2024 Valid 12Z Sun Sep 01 2024 - 12Z Tue Sep 03 2024 ...Areas of heavy rain with the potential for flash flooding across the south-central U.S. through Labor Day... ...Unsettled weather across much of the East continues today... ...Well above average, hot late-summer temperatures spread from the northwestern to north-central U.S. this holiday weekend... Areas of locally heavy rainfall will continue over portions of the south-central U.S. through the holiday weekend as a couple disturbances help to drive shower and thunderstorm chances. First, a lingering coastal low will bring more storms to the western Louisiana and upper Texas Gulf Coasts today (Sunday) with a Marginal Risk of Excessive Rainfall (level 1/4) and some isolated flash flooding. The low will drift southwestward Monday (Labor Day), bringing storm chances to the central Texas Gulf Coast. Meanwhile, additional storms are expected along and to the north of a lingering frontal boundary draped from north Texas southwest towards the Rio Grande, with another Marginal Risk area Sunday across southeastern New Mexico and central/western Texas. An embedded weakness in broader upper-level ridging aloft will help to encourage more widespread storms on Monday with a higher threat of heavy rainfall and scattered flash flooding, especially as soils become wetter given rainfall over the first part of the weekend. A Slight Risk of Excessive Rainfall (level 2/4) has been introduced for the Texas Hill Country where this threat is greatest, with a continued more expansive Marginal Risk across southeastern New Mexico and Texas. The widespread storms and clouds will keep temperatures below average through the weekend in the region, with highs generally in the 80s, and even some 70s on Monday for west Texas and eastern New Mexico. Showers and storms will also remain in the forecast for much of the eastern U.S. ahead of a lingering frontal boundary. The heaviest rainfall is expected today from the southern Mid-Atlantic/Carolinas west through the southern Appalachians where some isolated flash flooding will be possible. Locally heavy rainfall will also be possible west through the Tennessee Valley and into the Mid-South. More scattered, lighter showers are expected across the Northeast. A second, stronger cold front will bring drier air by Monday for most locations, though storms are expected to continue ahead of the front along the Carolina coasts southwest through Georgia towards the central Gulf Coast. Daily thunderstorms are also forecast for the Florida Peninsula. Forecast highs today range from the 70s in New England and the Great Lakes/Upper Mid-West to the 80s in the Mid-Atlantic and Ohio/Tennessee/Middle Mississippi Valleys and 90s deeper into the Southeast and Lower Mississippi Valley. The passing cold front will bring the more mild temperatures in the 70s further into the northern Mid-Atlantic and Ohio/Middle Mississippi Valleys Monday. An upper-level ridge will continue to bring well above average, hot late-Summer temperatures to the northwestern U.S. today as highs soar into the 80s to near 90 for the Pacific Northwest and mid- to upper 90s for the northern Great Basin. Heat Advisories remain in place for portions of the northern Great Basin given the higher threat for heat-related impacts. The ridge will shift eastward on Monday, bringing these hotter temperatures into the northern High Plains with forecast highs in the mid- to upper 90s. Those with plans this weekend should limit their time outdoors or seek more breaks from the sun in the shade, as well as remember to stay well hydrated. An upper-level low over the Pacific approaching in its wake will bring relief to the Pacific Northwest Monday as highs drop into the 70s, and conditions will return closer to average for the northern Great Basin with highs in the mid-80s to lower 90s. However, strengthening downsloping winds off the northern Sierra Nevada with the approach of the upper low on Monday have prompted a Critical Risk of Fire Weather from the Storm Prediction Center for northeastern California, southeastern Oregon, and northwestern Nevada. Elsewhere in the West, highs will be closer to average but still hot, with highs in the 90s for the Great Basin and interior central California, and 100s for the Desert Southwest. Conditions will be a bit cooler in the Four Corners region with highs in the 80s, and a few thunderstorms will be possible today. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php