Alaska Extended Forecast Discussion National Weather Service College Park MD 716 PM EDT Fri Oct 31 2025 Valid 12Z Tue 04 Nov 2025 - 12Z Sat 08 Nov 2025 ...Synoptic Overview... The synoptic pattern in the Alaskan domain continues to favor fast-moving cyclones to track west to east through the Aleutians then gradually dissipate over the Gulf of Alaska as a negatively- tilted upper ridge remains stationary across eastern mainland Alaska and further up into the Arctic Ocean in the form of an omega block. ...Guidance Evaluation and Preferences... The ensemble means from the ECMWF, GEFS, and CMC continue to show reasonable agreement on the above-mentioned synoptic pattern evolution through the medium-range period. Much of the uncertainty has to do with the timing of individual cyclones that are forecast to move from west to east near the Aleutians into the Gulf of Alaska through next weekend. Regarding the midweek cyclone that is forecast to move across the Aleutians, the GFS remains near the slow end of the model spread followed by the UKmet, while the ECMWF and CMC are near the fast end of the spectrum. The latest (18Z) GFS has sped up the cyclone to agree better with the rest of the faster guidance. These model spread characteristics are similar to those noted in the preceding cyclone. Toward the end of the medium-range period, model guidance shows good agreement for this cyclone to merge with the preceding cyclone over the Gulf of Alaska followed by gradual weakening. Meanwhile, both the deterministic and ensemble means indicate the arrival of what appears to be the next significant cyclone into the Aleutians by next weekend despite the large spread in the deterministic guidance. The Alaska forecast package is based on a general consensus of 40% from the 12Z ECMWF/00Z EC mean, 40% from the 12Z GFS/GEFS, and 20% from the 12Z CMC/CMC mean. This blend yielded an isobaric pattern reasonably compatible with yesterday's WPC forecasts. ...Weather/Hazards Highlights... The medium-range period will begin with a clipper cyclone whose center is forecast to pass through the central Aleutians on Tuesday before swiftly moving off to the southeast on Wednesday. The predicted pressure pattern appears to favor high winds on the back side of this system. Therefore, the "High Winds" area has been retained on the WPC Hazards Outlook map for the central to eastern Aleutians on Day 7 Wednesday 11/5. Precipitation amounts appear modest due to the speed of the system. Light precipitation is forecast to linger along the southern and southeastern coastal Alaska through much of the medium-range period as the offshore cyclones merge and then weaken. The merger will then edge closer to the coast toward the ridge axis that is forecast to anchor across eastern mainland Alaska and into Yukon Territories, keeping the light precipitation in place along the southern periphery of mainland Alaska. By next weekend, unsettled weather and strengthening winds appear to return for the Aleutians as model guidance indicates the arrival of the next significant cyclone from the west and southwest. Temperatures will be mostly above average for much of Alaska to start out the medium-range period. Gradual clearing skies will allow temperatures to return closer to normal for interior mainland Alaska while colder than normal readings are forecast for the Southwest, spreading north into the West as next week progresses. Kong 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 Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html