077 FXUS02 KWBC 181928 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 328 PM EDT Sun Oct 18 2026 Valid 12Z Wed Oct 21 2026 - 12Z Sun Oct 25 2026 ...Lingering Nor'easter offers East Coast Maritime Impacts... ...Southern California/Southwest/Rockies Heavy Precipitation... ...Overview... A lingering Nor'easter will bring wind and coastal flooding impacts to the East Coast into mid-late week. A cutoff low will support heavy rainfall from Southern California to the Four Corners states mid-to-late week along with some mountain snows. Associated activity will spread through the West Rockies and then work downstream with PLains system genesis. There is also an emerging onshore wet pattern for Florida to monitor late period. ...Guidance/Predictability Assessment... Guidance forecast clustering seems reasonably good for mid-later this week and a broad blend with focus on the models seems to provide a solid base forecast and messaging, bolstering forecast confidence. Model differences increase more significantly heading into next weekend, especially for stream separation with handling of ample Pacific energies set to work into a western U.S. mean upper trough. The 12 UTC models remain mixed. Instead, favor a solution trending more in line with better compatible GEFS/ECMWF ensemble means for max cycle-cycle consistency and NBM continuity. ...Weather/Hazards Highlights... A Nor'easter will offer threats for high winds and coastal flooding with stormy maritime conditions from the coastal Mid- Atlantic to off the Northeast. The storm will intensify off the Carolinas over the next few days and bring strong winds back to the coastline into mid-late week to protract a threat for beach erosion. The storm offers potential subtropical transition to monitor later week per NHC. Please refer to WPC's Key Messages on our website for more information: www.wpc.ncep.noaa.gov. A shortwave passing south of the Gulf of Alaska is forecast to dig/amplify into a cut-off low over the Eastern Pacific just off the West Coast into midweek and work inland into California and the Southwest later week. Lead anomalous moisture will feed into the West to support increasingly widespread rain/thunderstorms over the region and through the Great Basin/Rockies. WPC Excessive Rainfall Outlook Marginal Risk areas are in place for local runoff concerns, but rainfall should also aide lingering fire concerns. Some high elevation snowfall is likely for the Sierra through parts of the Intermountain West to the Rockies. The slow moving system will then eject downstream and lead cyclo/fronto genesis and return flow should support emerging showers/thunderstorms over the Plains by next weekend, albeit still with timing uncertainty to navigate. Upstream, a closed low with ample upper troughing will dig from the Gulf of Alaska to approach the Northwest and/or offshore late week. This system could generate moderate precipitation including high elevation snows into the Northwest as dependent on ultimate inland penetration to monitor with upcoming guidance. Meanwhile, mean upper trough development and lingering down though the Southeast U.S. may lead into a wet onshore flow period for especially southern Florida late period into next week. Kebede/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 $$