394 FXUS02 KWBC 191959 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Mon Oct 19 2026 Valid 12Z Thu Oct 22 2026 - 12Z Mon Oct 26 2026 ...Lingering Nor'easter offers East Coast Maritime Impacts... ...Southern California/Southwest/Rockies Heavy Precipitation... ...Overview... A potent lingering Nor'easter will bring high wind/wave and coastal erosion impacts to the East Coast into mid-late week. This maritime storm offers subtropical transition potential. Meanwhile, a cutoff low will support heavy rainfall from Southern California through the Great Basin/Rockies states mid-later week along with some mountain snows. Activity will spread downstream with PLains system genesis. An upper ridge wedged between over the Central U.S. will support above average temperatures through the weekend. Elsewhere of note, Bahamas upper low/trough settling and surface low pressure genesis may favor a wet onshore flow pattern for the Bahamas and back to southern Florida from this weekend/next week. ...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 by the weekend, especially for stream separation with handling of ample Pacific energies set to work into and downstream out from a western U.S. mean upper trough positions. Clustering would seem improved with discount of recent GFS/GEFS runs whose outlier solutions show less than stellar cycle to cycle continuity. Accordingly, favor a solution more in line with better compatible ECMWF/Canadian and ECMWF/Canadian 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 this week. The storm will intensify off the Carolinas 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 potent 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. Anomalous moisture will feed into the West to support increasingly widespread rain/thunderstorms over the region and through the Great Basin/Rockies. The pattern offers a fueling tropical moisture connection to T.S. Trudy forecast to lift/weaken from the south of Baja California. Accordingly, there's a slight risk (at least 15% chance) of excessive rainfall leading to flash flooding for portions of the Four Corners region, with a signal for heavy precipitation over the San Juan Mountains as well as the general southwestern Colorado area peaking on Thursday. The slow moving system will then eject downstream and lead cycle/fronto genesis and return flow should support emerging showers/thunderstorms over the Plains, especially with flow focus for the southern High Plains by the weekend, albeit with lingering timing uncertainties. Upstream, a closed low with ample upper troughing will dig from the Gulf of Alaska, amplify and work toward the Northwest this weekend into early next week. This potentially well organized system could generate moderate precipitation and cooling to support some high elevation snows across the Northwest as dependent on ultimate inland motion to monitor with upcoming guidance. Meanwhile, mean upper trough development and lingering down though the Southeast U.S. to the Bahamas may lead into a protracted wet onshore flow period for Florida this weekend into next week. The pattern may especially favor urban runoff issue potential, perhaps with focus from West Palm Beach through Miami/Southeast Florida. 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 $$