044 FXUS02 KWBC 081958 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 258 PM EST Mon Dec 8 2025 Valid 12Z Thu Dec 11 2025 - 12Z Mon Dec 15 2025 ...Potentially hazardous cold is possible for portions of the Northern Plains and Upper Midwest this weekend... ...Overview... A broad upper level trough with reinforcing shortwaves will continue to dominate areas east of the Rockies with broad ridging persisting along the West Coast through this weekend, though the amplitude of both may weaken some by next week. While the heavy precipitation and high wind threat fades in the Northwest, generally progressive clipper systems will be favored in this pattern east of the Rockies with enhanced northern tier wind/snow chances and lake effect snow in the lee of the Great Lakes. An arctic airmass will move in to portions of the north-central U.S. bringing much below normal temperatures and potentially hazardous cold. ...Guidance/Predictability Assessment... The guidance continues to show good agreement on the overall large scale pattern, but differences in the details which impacts sensible weather. For the first half of the period, a general deterministic model blend worked well as a starting point for the WPC surface fronts/pressures/500 hPa heights. For Sunday into Monday, there are some differences in the amplitude of the reinforced Eastern trough and Western ridge, with the GFS generally more amplified than the ECMWF or CMC. Leaned a bit heavier on the ensemble means late period to account for these differences. For sensible weather grids, the 13z NBM remains a good starting point, but did have to increase coverage of precipitation across the Northern Plains/Upper Midwest and into the Great Lakes (as well as the South) for some periods. ...Weather/Hazards Highlights... The heavy precipitation and wind threat across the Northwest is mostly in the short range period now, but precipitation should continue into Thursday. A Marginal Risk remains on the Day 4/Thursday ERO to account for saturated soils from prior days heavy rain. Snow is possible in the highest terrain of the Washington Cascades. A clipper system/disturbance into the northern High Plains will interact with a stationary frontal boundary and the northern Rockies to bring heavy snow threats to portions of central to eastern Montana Thursday- Friday, with several inches of snow possible. Additional energy rounding the base of the trough centered over the eastern third of the country will bring rounds of generally light precipitation, mainly snow, into the Midwest/Great Lakes and eastward towards the Appalachians and Northeast through the weekend. To the South, reinforcing fronts slowing as they approach Florida will bring daily rain threats near the Gulf Coast/Florida and possibly northward into parts of the Mid-South along frontal boundaries. A strong temperature gradient is forecast across the High Plains Thursday into early next week with 15-25F above average temperatures across the West and 20-30F below average temperatures Friday through this weekend from the Northern Plains across the Great Lakes, Midwest, and Ohio Valley. This may result in hazardous cold as morning temperatures dip below zero with wind chills near -20 degrees. This airmass will moderate somewhat as it moves into the Ohio Valley and East next week. Much of the South, Gulf Coast, and Florida will be near normal through the period. Santorelli 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 $$