792 FXUS02 KWBC 300701 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 301 AM EDT Wed Sep 30 2026 Valid 12Z Sat Oct 03 2026 - 12Z Wed Oct 07 2026 ...Major South/Southeast U.S. Excessive Rainfall/Flooding threat with tropical connections this weekend and early-mid next week... ...Guidance/Predictability Assessment... Guidance forecast spread continues to improve through medium-range time scales, again bolstering confidence. A favored composite of overall compatible model, ensemble mean and machine learning guidance seems to offer a solid forecast base for consistent threat messaging and products mainly in line with the National Blend of Models. Greater uncertainty remains with smaller scale convective interaction and local focus. The composite will tend to mitigate variance as consistent with individual feature predictability. ...Pattern Overview and Weather/Hazards Highlights... A main upper trough and wavy/wet frontal system will shift slowly eastward from the South-central U.S. into the weekend in separated southern stream flow. Leading excessive rainfall/flooding threats working into the South/Southeast will be fueled by tropical moisture from the remnants of Hurricane Polo and an increasingly deep and protracted lead Gulf inflow pattern with tropical influence. WPC Excessive Rainfall Outlook Marginal Risk areas with embedded Slight Risk areas cover from coastal Texas through the Gulf Coast states and Tennessee Valley/southern Appalachians then the Southeast for Day4/Saturday and Day5/Sunday. Meanwhile, systems within a more progressive northern stream flow will support passage of a series of wavy frontal systems down from the U.S. northern tier. These fronts will act to provide a northern rainfall shield focus and over-running boundary for lifting moisture/clouds before delivering a post-frontal fall temperatures/drier airmass southward with high pressure settling. This will act to shift southward and confine the lead focus for heavy rainfall/flooding threats down over the South/Southeast through early-mid next week to monitor given the ample repeat activity threat. Elsewhere, upper-ridging will lead to a period of above-average temperatures over the western U.S. including highs into the 90s and low 100s for central/southern California and the Desert Southwest. Some heat may reach hazardous levels for southern California this weekend/early next week. Schichtel 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 $$