Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EDT Thu Oct 08 2020 Valid 12Z Sun Oct 11 2020 - 12Z Thu Oct 15 2020 ...Lingering heavy rainfall possible from Delta over portions of the Appalachians and Mid-Atlantic... ...Much colder for parts of the West early next week... ...Overview and Guidance Evaluation/Preferences... Upper pattern will remain modestly amplified yet progressive next week as western troughing moves through the CONUS. The remains of Delta will lift out of the Tennessee Valley across the Appalachians as it gets embedded into a frontal boundary. This could carry at least modest to perhaps locally heavy rainfall through the Appalachians late Sun into Mon. Western trough will carry a surface cold front steadily eastward/southeastward all the way into Mexico and the Gulf of Mexico which will pave the way for cooler temperatures in its wake for much of the northern tier. Drier conditions are also expected later next week as another system into the West/Plains may have limited moisture. Through the 00Z/06Z guidance suite, the 06Z GFS and 00Z ECMWF paired well with their ensemble means to start with the remains of Delta and mostly with the western system but strayed apart with the next Pacific front into western Canada. There, the models/ensembles showed varied solutions so that the ECMWF ensemble mean was implored as a best middle ground option. In the east, the ensembles trended much quicker than just 24 hrs ago with the progression of the front, but much slower with the surface low well north in Canada. This resulted in a quicker pace and generally lower rainfall amounts in the East Mon-Tue. Ridging over the NW Atlantic may attempt to slow the front down by next Wed/Thu but given the inconsistencies in the guidance confidence is low. ...Weather/Hazard Highlights... Remnants of Delta along with the frontal boundary may yield a broad 1-2 inches of rainfall with some enhancement on southeast-facing terrain due to southerly flow ahead of the system. Some higher local amounts might result in minor flooding. cross the West, a potent trough will favor a few days of cooler than average temperatures in the Northwest/Great Basin/northern Rockies Sunday, spreading eastward Monday. By Tuesday, temperatures will moderate back to near average levels. Precipitation will move out of the West (some snow likely for the higher terrain) Sunday and expand across the Upper Midwest/western Great Lakes along and ahead of a warm front. Rainfall from leftover Delta moisture and the approaching front may converge over New England and/or southeastern Canada Tue-Wed. Temperatures Sunday will likely approach and exceed records over Texas ahead of the front, with 90s common and low 100s possible across the Rio Grande (perhaps into Monday as well around Brownsville). Near-record heat will also be possible across southern Florida near 90F Sun/Mon. 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