Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Thu Oct 12 2023 Valid 12Z Sun Oct 15 2023 - 12Z Thu Oct 19 2023 ...Guidance Evaluation/Predictability Assessment... Model and ensemble forecast spread overall remains below average Sunday into Tuesday in a pattern with seemingly better than average predictability. The WPC product suite was primarily derived from a blend of the 12 UTC GFS/ECMWF/Canadian/UKMET and GEFS/ECMWF ensemble means along with the compatible 01 UTC National Blend of Models. Blend weighting favoring the deterministic models in this period for details consistent with predictability was shifted increasingly to the ensemble means at longer time frames amid growing forecast spread/uncertainty. WPC product continuity is well maintained. A blend of latest 00 UTC guidance remains generally in line with the aforementioned forecast plan. ...Weather/Hazards Highlights... A dynamic upper trough/closed low and deepened surface low/frontal system will track through the Mid-Atlantic this weekend, leading to reformation as a coastal low/storm and maritime threat by Sunday. Expect enhanced winds and lingering but relatively modest/lingering wrap-around moisture and rains far around this multi-phased system over the Eastern U.S.. An influx of upper energies will continue to dig back into an amplified/unsettling mean eastern continent upper trough position through early-mid next week to the lee of at least initially amplified/warming upper ridging from the Intermountain West to the Canadian Prairies. Meanwhile upstream, a complex series of systems will act to amplify an eastern Pacific upper trough position and with gradual coastal intrusion to bring moisture inland to fuel moderate to heavy precipitation for the Northwest, but particularly favored southern facing terrain of the Pacific Northwest/Olympics in a wet period late weekend into next week. However, low enough precipitation rates do not seem to warrant an excessive rainfall risk area at this time. The cold front sweeping across the eastern U.S. Saturday into Sunday will bring temperatures generally 10 to 15 degrees below normal, including south Florida which will see near record high temperatures in the low to mid 90s through Saturday. Meanwhile, a building ridge over the west-central U.S. brings temperatures generally 5 to 10 degrees above normal west from the Rockies to the eastern lee of the Cascades. 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