Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
066 FXUS02 KWBC 031833 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 133 PM EST Wed Dec 3 2025 Valid 12Z Sat Dec 06 2025 - 12Z Wed Dec 10 2025 ...Overview... A central to eastern U.S. mean upper trough and broad cyclonic flow with reinforcing shortwaves will continue to dominate during much of the medium range period across the CONUS. This will favor below to well below normal temperatures for the Plains to the East Coast. Near to above normal temperatures are favored for the Western states under the influence of upper ridging. A lingering frontal system over the Southeast will likely promote an area of locally heavier rain while a couple of clipper systems will impact the northern tier states as well with with a modest snow chances. Heavier coastal rains and terrain enhanced snows may develop inland from the Pacific Northwest through the northern Rockies early next week along with a threat of high winds to monitor. ...Guidance/Predictability Assessment... Guidance continues to show good agreement synoptically through the medium range period but there remains quite a bit of uncertainty in the details and the timing of multiple shortwaves through the northern tier impacting sensible weather grids. A general blend of the deterministic model guidance continues to offer a good starting point for the first half of the period, with increasing weighting of the ensemble means onward into Days 6 and 7. The 13 UTC NBM seemed to provide a reasonably good starting point for most of the sensible weather grids, but did have to supplement NBM QPF to increase coverage of weekend light precipitation with systems moving through the north-central U.S./Midwest and also over the eastern Carolinas with frontal wave passage. I also generally increased winds/wind gusts from the Cascades eastward through the Great Lakes through the period in energetic and progressive flow. ...Weather/Hazards Highlights... Heavy rain along a frontal boundary should continue into Saturday for parts of the Southeast. The WPC Day 4/Saturday ERO shows a Marginal risk from the Florida Panhandle to far southern Georgia, along the frontal boundary, which may stall for a period of time allowing for some training of storms. Instability may be lacking overall which should limit the flash flood threat toward the I-10 corridor. By Sunday, some guidance shows rains hanging around along the trailing Florida cold front, but with lower amounts,so opted for no risk areas at this time for the Day 5 ERO. Several dynamic Pacific systems will push into western Canada and the Pacific Northwest, especially into next week, with rain/snow over WA/OR and eastward to the Northern/Central Rockies. This activity should be especially on the increase for the Pacific Northwest where some significant multi-day totals are possible and will be monitored for later period ERO threat area consideration. There is also a protracted risk for terrain enhanced winds into next week extending eastward into the north- central states. Several clipper like systems will also bring some rain and snow to parts of the Midwest, Great Lakes/Appalachians and the Northeast. Temperatures across the north-central U.S. to the East will remain below normal at least through the weekend, with some moderation from west to east early next week. This weekend, daytime highs and morning lows could be 10-15 degrees below normal in the Northern Plains/Upper Midwest, with this airmass transitioning into the East on Monday. The West will trend warmer into next week underneath upper ridging, with warmer than average temperatures also spreading into the central and southern Plains next Tuesday and Wednesday. Santorelli/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 $$