Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 628 PM EST Mon Feb 07 2022 Valid 12Z Fri Feb 11 2022 - 12Z Tue Feb 15 2022 ...Overview... An active storm track is expected in the northern Pacific south of the Aleutians late this week into early next week, with potential for relatively weaker surface lows to approach the Gulf and southern Alaska in southwesterly flow just east of an upper trough weakening over northwestern Alaska and the Bering Sea. These surface lows could enhance precipitation periodically in southern Alaska especially from the Kenai Peninsula into the Panhandle. Then the largest and deepest surface low should track south of the Aleutians early next week, with some chance to cross the islands by around Monday-Tuesday. But regardless of the exact track, given the low's breadth it is likely to affect the Aleutians with high winds, rough seas, and precipitation. ...Guidance/Predictability Assessment... Recent model guidance continues to show an elongated upper trough over northern and western parts of the mainland to start the period Friday, and a multi-model deterministic blend of guidance worked well for the WPC forecast at that point. These heights tend to rise a bit as the period progresses, though some level of troughing will be maintained. Meanwhile overall ridging builds across the eastern Pacific and into northwestern North America, but chances are still high for it to get disrupted by a potent shortwave around Sunday. Model guidance shows relatively good agreement with this overall pattern. However, plenty of differences remain in the details of individual shortwaves and surface low pressure systems, especially as they potentially approach southern AK. Recent models have persisted with a strong shortwave quickly moving across southern Alaska/Gulf/northern Pacific over the weekend, but timing differences are still an issue. The 12Z GFS and GEFS mean seems to cluster with the slowest shortwave, while the ECMWF (especially the 12Z deterministic but the 00Z ensemble mean as well) are faster. Preferred the middle ground placement of the 12Z CMC and 06Z GFS along with some incorporation of the NAEFS and EC means for that in the middle part of the medium range period. This shortwave also maintains an occluded low pressure system in the Gulf of Alaska through Sunday. Some low pressure systems in the series could be somewhat strong into the weekend, but there is still considerable run to run and model to model variability in their placement and strength. Guidance is most agreeable for a massive and deep (likely in the 960 mb range) low centered south of the Aleutians Sunday, which could take a northward turn Monday-Tuesday, with some guidance showing the low crossing the Aleutians. The ECMWF appears to be an outlier in splitting the low into pieces while other guidance maintains one low and with its faster track north crossing the Aleutians. But overall, considerable model differences in the placement of the low keep confidence low with the specifics. At this point, leaned toward the position of the ensemble mean guidance, which do keep the low centered south of the Aleutians through early Tuesday, though given the size of the low the Aleutians should be affected regardless. ...Weather/Hazard Highlights... Southwesterly flow between the Bering Sea upper low/trough and the East Pacific/far western Canada ridge will support wet weather over southern Alaska continuing into the weekend. Individual surface lows will periodically help to focus heavier episodes of rain in low/coastal areas and heavy snow in higher elevations. Highest totals are likely to be from the southeastern coast through the Panhandle, particularly through early Saturday, while amounts over locations farther west in the Alaska Peninsula and Southcentral Alaska will depend more on exact storm tracks with the series of low pressure systems. Some light snow may extend farther north into central parts of the mainland over the weekend. Each storm could also produce brisk to strong winds and rough seas between the Aleutians/Alaska Peninsula and the Panhandle, with the most likely period of high winds next Sunday-Tuesday in the Aleutians per the current forecast storm track. Precipitation could also increase somewhat for the Aleutians early next week. Below normal temperatures are expected for the western mainland with lesser cold anomalies for the North Slope through the period underneath the trough. Generally near normal temperatures are forecast elsewhere, but with the largest above average anomalies across the southeastern mainland. Tate 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 Hazards: - Heavy precipitation across the northern portion of the Alaska Panhandle, Fri-Sat, Feb 11-Feb 12. 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