Extended Forecast Discussion NWS Weather Prediction Center College Park MD 253 PM EDT Fri Oct 09 2020 Valid 12Z Mon Oct 12 2020 - 12Z Fri Oct 16 2020 ...Overview... Upper troughing is forecast to progress eastward and carry a lead cold front to the East Coast midweek. Leftover moisture from Delta will surge northward in tandem with a warm front through the Mid-Atlantic into the Northeast, leading to modest to perhaps locally heavier rain. In the Northwest, a couple incoming Pacific systems will bring bouts of rain and high elevation snow to the area early in the week before it trends a bit drier and milder. ...Guidance Evaluation/Preferences... Longwave pattern evolution was in good agreement among the ensembles, but embedded systems remain tougher to forecast. Blended solution near the 06Z GFS/GEFS and 00Z ECMWF/ECMWF ensemble mean (about 40/60) offered a reasonable starting point. Ensembles have trended more amplified with the pattern by the end of next week, especially over the higher latitudes. This would increase the expected ridge/trough pattern across the CONUS later next week over the West/East, respectively. Weighted the ECMWF ensembles more than the GEFS ensembles which as the former showed more amplification than the latter. Both the Canadian and UKMET showed too much variability from the GFS/ECMWF-cluster to use in the blend. ...Weather/Hazard Highlights... The cold front moving across the central/eastern U.S. combined with above average moisture from the remnants of Delta should lead to a broad 1-2 inches of rainfall across portions of the Northeast. Some higher local amounts might result in minor flooding. Ahead of this front, warm temperatures are forecast, especially for morning lows, which could be 15-20 degrees above normal across the Ohio/Tennessee Valleys to Mid-Atlantic Mon/Tue. Cooler temperatures will follow behind the cold front into the northern Plains into the Great Lakes Thu/Fri. Farther west, a cold front should move across the Northwest Tue before sweeping across much of the country as the week progresses, but with limited moisture. Additional lighter rain and perhaps mountain snow could affect coastal Washington later in the week as a system well off the coast moves toward the Gulf of Alaska. Warm/hot temperatures are possible over the Southwest later next week as upper ridging takes hold. Upper 90s to low 100s are forecast for the lower deserts of AZ/CA/NV. Fracasso WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices 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/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml