Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Thu Aug 8 2024 Valid 12Z Sun Aug 11 2024 - 12Z Thu Aug 15 2024 ...Excessive Heat lingers over portions of Texas and the central Gulf Coast into next week... ...Overview... The upper low that tracks just north of the Great Lakes and is responsible for pushing Debby remnants out of the Northeast by Saturday morning lingers over the Northeast as a trough into Tuesday. This will maintain a cooler/drier air mass to much of the Northeast/Mid-Atlantic through early next week. Upstream over the West and central states, upper ridging centered over Texas will maintain monsoonal flow over the Southwest/southern Rockies into the middle of next week with heat concerns persisting from Texas to the central Gulf Coast. Minor/mainly dry troughing over the Pacific Northwest will linger through the period. ...Guidance/Predictability Assessment... The 18Z GFS and 12Z ECMWF/CMC/UKMET had good agreement for Days 3-5 with the Northeast and Northwest troughing and south-central ridging. For Days 6/7 the 12Z ECENS/18Z GEFS means were included for the midweek pattern. For QPF the 01Z NBM was directly blended with the 12Z ECMWF/CMC with some 18Z GFS in targeted areas including the southern Plains where there is a heavy rain threat on Days 4/5. ...Weather/Hazards Highlights... Monsoonal moisture flow on the western side of the ridge centered over Texas will keep a wet and unsettled pattern in place from the Four Corners region northward into the central Rockies/High Plains for Sunday/Monday. Marginal EROs are in Place here for Days 4/5. With the surface high shifting east to the Midwest on Sunday, the clockwise flow opens the western Gulf to eject moisture up the Plains in a bit of a disjointed manner with the Rockies on Sunday, that then connects across the High Plains on Monday, so a separate Marginal Risk extends from South Dakota down the eastern side of the Plains through the Ozarks on Day 4. The connected Marginal on Day 5 extends east to the Mid-South. Convective processes that are not handled well in global models will likely cause further adjustment to these areas with possible upgrades in the coming days, so stay tuned. Finally, a persistent front over the Southeast/Carolinas looks to produce widespread rain with embedded heavier rain where recent excessive rainfall from Debby has resulted in fully saturated soils that may only partially recover by then. Marginal Risks are in effect in this part of the Southeast for Days 4/5. Above seasonal normal temperatures persist over Texas to the central Gulf coast into next week down stream of a ridge axis over west Texas. HeatRisk values will be at Moderate to Major levels with some isolated Extreme values. Below normal temperatures over the central U.S. persists behind a cold front into Monday before return flow brings temps back toward normal. Jackson 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 (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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