240 FXUS02 KWBC 251834 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 234 PM EDT Fri Sep 25 2026 Valid 12Z Mon Sep 28 2026 - 12Z Fri Oct 02 2026 ...Early season New England Nor'easter lingers early next week... ...Multi-day Four Corners states to Plains/Mississippi Valley heavy rain/runoff/tropical moisture connection threat next week... ...Overview... An early season Nor'easter will linger off New England early next week before exiting into the Canadian Maritimes. Strong/gusty winds with potential for coastal flooding, beach erosion, and rip currents are possible, along with heavy coastal rains. Meanwhile, an upper trough will work through the West/Southwest early next week and move east into the Plains midweek and beyond. Heavy precipitation will be widespread ahead of this trough and with lead/wavy multi- stream frontal system interactions. A tropical moisture connection as East Pacific Hurricane Polo landfalls in Mexico favors multiple days of rain/storms and some mountain snows in the Four Corners states, with widespread heavy rainfall/runoff issues spreading across the Plains and Mississippi Valley as next week progresses. ...Guidance/Predictability Assessment... The large scale forecast and evolution show reasonable agreement, but there remains some considerable uncertainties on the smaller scale, leading to notable and potentially high impact differences in the sensible weather associated with systems. Forecast confidence remains high with the development and lingering of an early season Nor'easter, but models continue to come into better alignment on how long this system may linger off the Northeast coast. Certainly by early next week though, the system should begin to push off towards the Canadian Maritimes. Across the central U.S., there remains question on timing of a cut off low over the Southwest and its progression into the south- central U.S. next week. Regardless though, confidence is higher for leading tropical moisture from East Pacific Hurricane Polo to enhance rainfall across the Southwest into the Central U.S.. Recent 12z GFS run comes into better agreement showing an overall slower trough progression and absorption of Polo into the larger flow around Wednesday of next week. ECMWF remains a bit slower as well. WPC progs favor the slower ECMWF/ECENS/EC-AIFS solutions which have shown better run to run continuity and also is more consistent with the official NHC track for Polo. ...Weather/Hazards Highlights... The western Atlantic Nor'easter will lead to broad onshore flow from the Mid-Atlantic to the Northeast, continuing early next week. The lingering storm could lead to coastal flooding and beach erosion, as well as marine hazards like rip currents and high surf. Heavy rain could cause inland flooding across southeastern New England. See WPC's Key Messages regarding this coastal low for further information. Deep tropical Pacific and Gulf moisture should return ahead of the large-scale troughing into an unsettled/cooled West, bringing widespread rain to the Four Corners states northward and eastward into early next week. Moderate to heavy rain spreads across the Plains and Mississippi Valley into early-mid next week. A slow moving upper low will interact with tropical moisture from Polo, leading to heavy to excessive rainfall threats across the Four Corners Monday to Tuesday/Wednesday. A WPC Excessive Rainfall Outlook (ERO) Slight Risk area is in place for Monday. Vulnerable soils from recent heavy rainfall could exacerbate flash flooding concerns. Some snow is possible in the higher peaks of the Intermountain West/Rockies with the precipitation, as the trough pushes east into the Plains on Wednesday/Thursday and cools temperatures. A Slight Risk ERO has also been introduced for the south-central U.S. for Tuesday, with later week risks to monitor. Meanwhile, a wet period for Florida is expected to linger into early October as onshore moisture flow fuels enhanced daily rain chances. Warmer than average temperatures will persist in the south-central U.S. into early next week under an upper ridging, and highs in the 90s are forecast through the southern Plains and Lower Mississippi Valley. On the other hand, cooler than average temperatures (especially for highs) are forecast for the West under troughing aloft, gradually spreading eastward early next week and helping to moderate temperatures in the Plains by midweek. Temperatures could reach around 10 degrees above normal in the East ahead of the trough Wednesday-Thursday. Santorelli/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 $$