501 FXUS02 KWBC 040703 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 203 AM EST Thu Dec 4 2025 Valid 12Z Sun Dec 07 2025 - 12Z Thu Dec 11 2025 ...Moderate to strong multi-day AR possible for the Pacific Northwest next week... ...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 into at least early next week. Near to above normal temperatures are favored for the Western states under the influence of upper ridging. A lingering frontal boundary over the Southeast will likely promote an area of locally heavier rain this weekend while a couple of clipper systems will impact the northern tier states as well with with modest snow chances. A couple of Atmospheric Rivers into the region will bring heavier coastal rains and terrain enhanced snows from the Pacific Northwest through the northern Rockies 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 shortwave dropping into the Upper Midwest next Wednesday shows some notable amplitude differences with the CMC much flatter than the ECMWF and GFS. The GFS also becomes faster than consensus with this as it pushes through the Ohio Valley into the Northeast by Thursday. Out West, guidance shows good agreement on a couple of shortwaves impacting the region early to mid next week. By Thursday though, the GFS brings another shortwave into the region while the CMC and ECMWF suggest upper ridging, and are consistent with the ensemble means. For the WPC forecast, a general blend of the deterministic model guidance was a good starting point for the first half of the period, with increasing weighting of the ensemble means (with the ECMWF) onward into Days 6 and 7. Given the overall agreement, the 01 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 light precipitation with systems moving through the north- central U.S./Midwest. ...Weather/Hazards Highlights... Moderate to heavy rainfall may continue into Sunday across northern Florida along a lingering frontal boundary. This frontal boundary may stall for a period of time, allowing for some training of storms into the Sunday afternoon period, although instability will be lacking so next expecting a widespread flash flood threat. A marginal risk was added to the Day 4/Sunday ERO to account for at least a localized threat. Rain should finally clear out of the region by next Monday. A shortwave looks to move into the Pacific Northwest around Sunday, bringing some potential for moderate rain and mountain snows. The next one beginning Monday looks quite a bit stronger with latest CW3E guidance suggesting at least a moderate if not strong AR due to both higher IVTs and a longer duration event. Some significant multi-day totals are possible both with coastal rain and higher elevation snows across the Cascades. Did go ahead with a marginal risk for western Washington and far northwest Oregon on the Day 5/Monday ERO, with likely needing additional risk areas beyond Monday once it gets into the ERO period. There is also a risk for terrain enhanced winds into next week extending eastward into the north- central states. Elsewhere, several clipper like systems will also bring some rain and snow to parts of the Midwest, Great Lakes/Appalachians and the Northeast next week. 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. On Sunday, daytime highs and morning lows could be 20-25 degrees below normal parts of the Northern Plains/Upper Midwest, with temperatures 10-20 degrees below normal by Monday into the Ohio Valley and Northeast. After Monday, temperatures should moderate with another shot of cold air into the northern tier by next Thursday. The West will trend warmer into next week underneath upper ridging, with warmer than average temperatures also spreading into the central and southern Plains by 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 $$