Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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613 FXUS02 KWBC 221858 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 158 PM EST Sat Nov 22 2025 Valid 12Z Tue Nov 25 2025 - 12Z Sat Nov 29 2025 ...General Overview... A weakening low pressure system will track northeast towards the Ohio Valley on Tuesday while another storm system strengthens over the northern Plains and Upper Midwest. This northern system will become the dominant weather feature by mid-week and will bring widespread precipitation chances to the northern and eastern U.S., with potentially heavy snow in the Upper Midwest. Meanwhile, periods of rain and mountain snow are likely for the Pacific Northwest with an active storm track over the northeast Pacific, and an upper trough will likely amplify over the interior West later in the week. ...Guidance/Predictability Assessment... Model guidance has shown improving agreement today, resulting in above average confidence in the upper level and broad synoptic pattern. There still remains some uncertainty in the details of individual systems, but that is to be expected at this time range. There were no model outliers today, except maybe the GFS towards the end of the period, which is not as pronounced as the ECMWF/CMC with the deepening upper trough/low over the West. Given good agreement, a near even blend of the latest deterministic model runs from the GFS/ECMWF/CMC/UKMET provided a good starting point for the WPC forecast. Ensemble means from the GEFS/ECENS/CMCE were added in increasing amounts through the second half of the period to help smooth out model differences. ...Weather/Hazards Highlights... The low pressure system that is forecast to bring heavy rain to the south-Central U.S. Sunday into Monday will track northeast while weakening on Tuesday. Showers and thunderstorms are expected ahead of the system across the eastern U.S., and locally heavy rainfall will be possible over the interior Southeast. To account for this, there is a Marginal Risk of excessive rainfall in the Day 4 (Tuesday) Outlook from eastern Mississippi to the southern Appalachians. Precipitation is also expected across the north-central and northeastern U.S. on Tuesday as another low pressure/frontal system strengthens over the northern Plains and Upper Midwest. Wintry precipitation is expected along the northern side of the system, and a swath of moderate to potentially heavy snow will be possible from eastern North Dakota through northern Minnesota. The two low pressure systems will translate east across the nation on Wednesday then push offshore by Thursday, with lingering precipitation chances along the East Coast on Wednesday. Northwesterly winds on the backside of the system will result in lingering lake effect snows downwind of the Great Lakes Wednesday through Friday. Meanwhile, precipitation chances will increase across the Northwest as several Pacific frontal systems move into the region throughout the week. The heaviest precipitation is forecast across western Washington and northwestern Oregon on Wednesday, which may result in isolated flooding concerns along the coast and favored upslope regions of the Olympics and Cascades. There is a Marginal Risk of excessive rainfall for these areas in the Day 5 (Wednesday) Outlook. Precipitation will fall as snow in the higher elevations, and locally heavy snow may be possible in the Cascades in Washington. Temperatures are expected to be mild for this time of year from the Gulf Coast to the Great Lakes on Tuesday and for the East Coast on Wednesday, with high temperatures running 10-15 degrees above average. A cold front will bring a return to slightly below average temperatures for the Central and Eastern U.S. mid-to-late week. A modest warm-up is likely for the northwestern U.S. towards Thanksgiving as the early colder airmass modifies and flow from the Pacific moves into the region. Dolan/Hamrick 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 $$