786 FXUS02 KWBC 291855 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EDT Wed Oct 29 2025 Valid 12Z Sat Nov 01 2025 - 12Z Wed Nov 05 2025 ...Overview... Guidance continues to advertise an amplified upcoming medium range pattern aloft, at least through this weekend, which features mean troughing over the eastern U.S. and a building ridge out west. A potent shortwave drops southward from the Upper Midwest on Saturday to bring renewed amplified troughing over the East with still varied recent guidance overall still continuing to trend toward more stream separation with a possible cutoff closed low over or near the Gulf Coast region/vicinity by early next week. The tail end of an atmospheric river will keep the Northwest still wet into Saturday, but drier into early next week with upper ridging. Another deep trough will approach the West Coast by around Wednesday of next week. ...Guidance/Predictability Assessment... A main forecast concern continues to be with the shortwave trough dropping southward to the Midwest into Saturday, with possible cutoff closed low development over the Mississippi Valley to Gulf Coast by Sunday or Monday. Latest guidance trends continue to be for this scenario. Recent CMC runs advertised a more progressive amplified trough through the region, but the latest 12 UTC run has at least trended more amplified/less progressive. There is also uncertainty in whether any sort of closed low will linger near the Gulf Coast or lift off the Southeast coast. A few GFS and ECMWF runs have recently offered this latter possibility, but it is not shown in either's new 12 UTC run that are more in line with the GEFS/ECMWF ensemble means. The AIFS is more progressive than that solution now, but the AIFS ensemble mean is slower. Accordingly with uncertainty, the WPC forecast is close to the GEFS/ECMWF ensemble means that show stream separation and fairly slow progression that seems a good match to the larger scale flow. Out West, there is question on the timing of the next trough towards the coast late period and an ensemble mean blend seemed a good starting point with a gradual slower trend recently that seems consistent with amplifying flow. ...Weather/Hazards Highlights... A departing strong surface low out of the Northeast/Canadian Maritimes will induce lake effect rains behind it. The shortwave dropping through the Midwest may bring some uncertain light rain showers with it, but additional rainfall may develop along the Gulf Coast with weak surface low development along a trailing frontal boundary in the Gulf. Rain coverage may expand for the Southeast and East Coast early next week, but with much uncertainty and highly dependent on the pattern evolution into this region. Locally moderate to heavy precipitation may linger into Saturday on the back end of a moderately strong atmospheric river into the Northwest late this week. But by Saturday, instability should be less and the better moisture anomalies will be quickly shifting eastward, so no marginal risk is planned at this time on the ERO since Friday should be the bigger day. Most precipitation is forecast to stay rain other than snow in the highest peaks of the Olympics and the Cascades. The region should trend drier Sunday with possibly another increase in precipitation early-mid next week again. Elsewhere, the Southwest to the Plains should stay mostly dry through the period under the warming ridge aloft. Much of the West can expect warmer than average temperatures underneath upper ridging through the period, expanding into the Central U.S. Sunday onward. Meanwhile, the East will be near to just below normal temperatures underneath mean upper troughing. 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 (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 $$