Extended Forecast Discussion NWS Weather Prediction Center College Park MD 236 AM EDT Sun Sep 24 2023 Valid 12Z Wed Sep 27 2023 - 12Z Sun Oct 01 2023 ...Overview... The pattern through the middle to late parts of next week features an amplifying upper trough over the West, increasingly amplified ridging which expands from the Plains through the Midwest towards the Appalachians which escorts a trough eastward into the western Atlantic. ...Guidance Evaluation/Predictability Assessment... There is some increased convergence in the guidance with the Western trough, with the Canadian slowly but surely trending towards the GFS/ECMWF/NAEFS/ECMWF ensemble mean solutions, which increases confidence in the forecast scenario. The initial blend is a fairly even blend of the 12Z ECMWF/UKMET/Canadian into Friday morning. Thereafter, the blend increasingly relied on the 12Z ECENS/12z NAEFS means. QPF grids are from the 01Z NBM enhanced with the ECMWF/GFS/Canadian through about Day 5, and the ECMWF/GFS thereafter. The remainder of the grids are primarily 01z NBM based, with adjustments to the PoPs based on the resultant QPF blend. ...Weather/Hazards Highlights... An early season storm system will bring active weather to the Pacific Northwest through next week. Rounds of heavier precipitation are expected. However, given generally lower rainfall rates/totals expected, no excessive rainfall areas appeared needed. Snow at higher elevation becomes increasingly favored with time across the Northern Rockies as the upper level trough strengthens. A stalled front over the Florida Peninsula through much of next week will bring periodic heavy rains mid week. There's enough agreement signal-wise on heavy rainfall in and near portions of northern FL and south GA to introduce a Marginal Risk area for day 4/Wednesday into Thursday morning. For the following day, the 00z ECMWF and 00z UKMET depart from the other guidance in shifting heavy rainfall up the Mid-Atlantic coast. For now, no risk area has been depicted for day 5/Thursday into Friday morning. Increased ridging over the center of the country and troughing farther west, will make for an increasing temperature trend in the Plains/Great Lakes and decreasing across the West. Below normal temperatures over the Mid-Atlantic States can be expected through midweek before moderating on approach of the ridge. Roth/Jackson 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