Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
764 FXUS02 KWBC 140734 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 334 AM EDT Tue Oct 14 2025 Valid 12Z Fri Oct 17 2025 - 12Z Tue Oct 21 2025 ...Guidance/Predictability Assessment... Medium-range guidance shows good mid-larger scale agreement on an amplified upper pattern evolution. An amplified western U.S. trough into Friday will work steadily eastward to the East Coast by early next week as a lead warming downstream ridge shifts from the east- central U.S. Friday to the western Atlantic on Sunday. Upstream, an amplified upper trough/low is slated to breach the West Coast into early next week. Overall, favor a composite blend of best clustered guidance of the 18 UTC GFS/GEFS, 12 UTC ECMWF/ECMWF ensemble mean and Canadian ensemble mean and 01 UTC National Blend of Models guidance for much of this forecast period. This solution holds good WPC continuity mainly in line with new 00 UTC guidance composite. ...Weather/Hazards Highlights... Lingering upper troughing in Atlantic Canada (tied to the current coastal storm) still supports continued unsettled/windy conditions over New England through late week with cooler than normal temperatures to start that will slowly moderate. The troughing and associated surface frontal boundary in the West will promote cool and showery (with some snow at higher elevations) conditions over the Northern/Central Rockies to start, with broader light rain in advance of the surface low that is poised to track from the Northern Plains into southern Canada. As the attendant cold front passes through the Plains, moisture will increase in advance of it through the Mid-MS Valley where rainfall could increase by Saturday. The WPC Day 5/Saturday Excessive Rainfall Outlook (ERO) introduces a Marginal Threat area centered over the Mid-South given favorable upper support and return flow. This rainfall will continue eastward next Sunday and Monday/Tuesday into the Northeast near the track of deepening/consolidating low pressure (and into the Southeast ahead of the cold front). Temperatures will be mild ahead of the cold front with values well into the 70s/80s Friday from the Corn Belt to the Ozarks with 90s across South Texas. By late next weekend into early next week, another deepened system will enter the Pacific Northwest/West Coast with another round of valley rain and higher mountain snow that will then dig and spread across the West and downstream to the Rockies. The Day5/Saturday ERO introduces a coastal Washington Marginal threat area given a favorable guidance signal. 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 (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 $$