Preliminary Forecasts
Issued by NWS
Issued by NWS
843 FXUS02 KWNH 030828 PREEPD Preliminary Extended Forecast Discussion NWS Weather Prediction Center College Park MD 428 AM EDT Fri Oct 3 2025 Valid 12Z Mon Oct 06 2025 - 12Z Fri Oct 10 2025 ...General Overview... Upper ridging over the Eastern Seaboard will shunt south and shift west over the Gulf Coast Monday through Tuesday where it will persist through next week. Meanwhile a more transient upper pattern continues over the central/northern states with a deep trough swinging through the Great Lakes Tuesday into Wednesday. A cold front a Canadian surface high pressure follows this trough with cooler than normal temperatures tracking from the northern Plains Tuesday to the Northeast by late week. Farther south, tropical moisture interacting with a lingering stationary front may produce heavy thunderstorms over Florida, Georgia, and into South Carolina Monday. Finally, deep upper troughing looks to amplify along/off the Pacific Northwest coast later next week. ...Guidance/Predictability Assessment... A major shift in the 00Z guidance is noted over prior runs with stronger ridging over Florida Monday into Tuesday with markedly less QPF in SC/GA. Also the 00Z ECMWF is much slower with tropical activity/QPF into the Desert Southwest later next week compared to the 12Z run. Also, the late week troughing over the Northwest looks to be slower and farther west/offshore in the 00Z guidance compared to the previous. Quite remarkable how stark the differences are with Days 4/5 QPF in the Southeast and Days 6/7 in the Southwest. However, much of this was noted in the 12Z/18Z EC-AIFS runs which once again seems to be leading global deterministic guidance in overall synoptic pattern recognition. By the way the UKMET is no longer available for usage in our blending process, so the WPC forecast relied heavily on the EC/GFS with some CMC Days 3-5 before going heavier on the ECENS means for 6/7. ...Weather/Hazards Highlights... Despite 00Z guidance having marked reductions in Southeast QPF Monday/Tuesday, the new Day 4 ERO remains Marginal with some shifts south and inland. The moisture anomalies are now generally focused over the FL Peninsula into GA/AL, so this are will need continued monitoring for excessive rain. A cold front ahead of a powerful trough pivots over the central Plains into the Midwest Monday. The risk of repeating heavy rain warrants maintenance of a Marginal Risk for Day 4 from central KS through the IL/WI border. The area was shifted south a bit based on 00Z consensus trending more toward the greater instability to the south. Moisture anomalies increase over New Mexico Tuesday from continued surges of moisture from the western Gulf onto a frontal wave that is stalled over northern NM. Introduced a Day 5 Marginal Risk for much of NM. Considered a Slight Risk, but given the notable run- to-run changes in guidance a Marginal will suffice for now. Temperatures will be below normal under troughing over the Intermountain West Monday with that cooler trend shifting east with a cold front over the Northern Plains Tuesday, the Midwest Wednesday, and the Eastern Seaboard for Thursday/Friday. Meanwhile, ridging over the Gulf Coast will maintain above normal temperatures over Texas and Louisiana through next week. Jackson 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 $$