Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 754 PM EDT Mon Mar 14 2022 Valid 12Z Fri Mar 18 2022 - 12Z Tue Mar 22 2022 ...Overview... The most notable feature over Alaska for the medium range period will be an upper low with possibly multiple centroids at times meandering in the Gulf of Alaska as a potent upper-level shortwave diving southward across the Bering Sea as well as energy along an active storm track across the northeastern Pacific will serve to redevelop and reinforce the closed low through early next week. This pattern will support a series of surface low pressure systems and bring a sustained period of inclement weather through the Panhandle and occasionally up into the southern coasts for much of the period. ...Guidance/Predictability Assessment... Model guidance shows fairly good agreement with the overall pattern of a reloading upper low over the Gulf, with perhaps a bit more spread compared to the past couple of days with the details. By Day 5/Saturday, GFS runs are showing more of a double barreled upper low as energy approaches from the Bering Sea, while the ECMWF/CMC/UKMET have more interaction and one combined low. The latter solution is closer to continuity and shows more agreement overall, so leaned toward a more combined low feature, but even the ECMWF does have some energy lingering over Bristol Bay, so a compromise of deterministic guidance including the ECMWF, GFS, CMC, and UKMET seemed like a good middle ground to indicate this possibility but not jump on it. Troughing should amplify across the state and southward well into the Pacific as Bering Sea ridging builds early next week. Embedded within the trough, the low may reform or retrograde west of Kodiak Island Sunday/Monday due to additional energy interaction from the northeastern Pacific, and slowly track eastward Tuesday over the Gulf. The 12Z ECMWF appeared to be somewhat of an outlier by Monday-Tuesday as it drifts the original upper low east more quickly. Farther north, the GFS indicates stronger energy diving into the trough for interior Alaska around Sunday compared to other guidance, which is possible if arctic energy combines that way but uncertain at this point. The overall meandering and energy interactions aloft lead to surface low position and strength differences as well. Thus WPC forecast phased in about half of the GEFS/EC ensemble means by days 7-8 to alleviate the individual model differences, while maintaining some operational guidance in the blend for strength of systems. ...Weather/Hazard Highlights... Precipitation is expected to focus along southern parts of Alaska given the northern Pacific storm track. Southcentral Alaska to the Panhandle in particular should see rounds of enhanced precipitation, with increasing and decreasing intensity depending on location of the surface lows and the orientation of the upper trough/low. While precipitation does not appear to be very intense, recent heavy rain/snow across the area could make it more sensitive to additional impacts, and amounts may pick up by early next week. In addition, brisk winds are expected with the approach of a surface low Friday-Saturday with some gusty winds possible across the Panhandle. On the other side of the lows, periods of breezy northerly winds are expected over the Aleutians, along with some chances of snow showers. Snow is also possible for the eastern mainland over the weekend. Colder than average high temperatures are forecast for much of Alaska given troughing aloft, with highs generally 10-20F below normal for mid-March across the southwestern mainland and Alaska Peninsula on Friday and Saturday as a reinforcing cold front comes through. These cooler temperatures will spread into much of the interior as well. However, low temperatures should be closer to normal with some areas even above normal for lows. The North Slope and the southeast mainland are forecast to be closest to average. Meanwhile, the Panhandle should see below normal highs through the period and a mix of above and below normal lows. 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 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