Preliminary Forecasts
Issued by NWS
Issued by NWS
020 FXUS02 KWNH 020733 PREEPD Preliminary Extended Forecast Discussion NWS Weather Prediction Center College Park MD 233 AM EST Tue Dec 2 2025 Valid 12Z Fri Dec 05 2025 - 12Z Tue Dec 09 2025 ...Record cold likely for the Corn Belt/Midwest/Mid-Atlantic through Friday... ...Overview... Broad cyclonic flow will continue to dominate during much of the medium range period across the CONUS as a result of upper lows anchored over Canada and Alaska. This will favor below to well below normal temperatures for the Plains to the East Coast, with record cold lows (and cold highs) likely into Friday from the Corn Belt to parts of the Mid-Atlantic. Near to above normal temperatures are favored for the Western states downstream of the core of the upper ridge. With the upper trough touching the Gulf Coast late this week, a frontal system there will move eastward and promote an area of locally heavier rain along the I-10 corridor. Trend by the weekend continues to be for a flatter system to exit out to sea thereafter, but some generally light wintry precipitation is possible on its northern side. A couple of clipper systems will impact the northern tier states as well through the period. ...Guidance/Predictability Assessment... Guidance continues to show good agreement synoptically, but plenty of uncertainty in the details which impacts sensible weather grids. There are some differences across the Midwest this weekend with some weak shortwaves, and then the CMC is sharper with a shortwave down towards the Gulf Coast early next week. Some uncertainty with timing of upper ridging in the West as well. Even so, a general model blend sufficed for the first half of the period, with increasing weighting of the ensemble means on Days 6 and 7. This meant the 01z NBM was a good starting point for most of the sensible weather grids, but did have to supplement the QPF grids with deterministic guidance to increase coverage of light precipitation associated with the systems through the Northern Plains and Midwest. ...Weather/Hazards Highlights... Heavy rain along a frontal boundary will spread into the Southeast Friday and possibly into Saturday. The WPC Day 4/Friday ERO continues to show a Marginal risk across parts of the Southeast 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 Saturday, some moderate to heavy rain may linger across northern Florida and so a marginal risk was raised on the Day 5/Saturday ERO for that area. The whole system will lift out to sea by Sunday, but may still spread some light precipitation (rain/snow) on its northern side across the Mid-Atlantic and perhaps New England. Over the Pac NW, several Pacific systems will push into western Canada during the period with rain/snow over WA/OR and eastward to the Northern/Central Rockies. Some clipper like systems will bring rain and snow to parts of the Midwest and Great Lakes as well. Surges of below average temperatures continue for the central and eastern U.S. into late week as the sprawling low over Hudson Bay persists. A surge from the northern Plains through the Northeast occurs into Friday with low temperatures of 5 to 20 degrees below zero, which will likely set daily record lows. High temperatures in the teens and low 20s on Thursday will also set daily records for cold high temperatures. The next cold surge may follow the same path but perhaps be of lesser magnitude this weekend. The West will see above normal temperatures (especially the Great Basin) late week through this weekend, expanding into the Rockies and possibly the Plains by next Tuesday. 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 $$