Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EST Tue Nov 22 2022 Valid 12Z Sat Nov 26 2022 - 12Z Wed Nov 30 2022 ...Overview... Most guidance shows a fairly progressive pattern aloft with a series of troughs and ridges, with a general tendency for these features to become more amplified with time. This regime will support a succession of surface lows/fronts across the Bering Sea/Aleutians into the Gulf of Alaska/Northeast Pacific, with primary precipitation emphasis from the Aleutians through parts of western and southern Mainland Alaska as well as the Panhandle. Meanwhile, high pressure building into the northern portion of the state during the weekend and shifting into western Canada early next week should favor driest conditions over northern/northeastern areas. ...Guidance/Predictability Assessment and Preferences... The 12Z model guidance suite, along with the 18Z GFS, indicates the strong low over the northern Gulf Saturday morning should stay just offshore while weakening this weekend. The ECMWF is slightly farther north across the southern islands of the southeast panhandle, and the CMC is a bit slower in bringing this low towards the southeast and down the British Columbia coast. For the storm system approaching the Aleutians/Bering by Sunday, there is still considerable model spread here with the GFS continuing to depict a more northern track, whereas the CMC is quicker in weakening this storm. Looking ahead to early next week, the GFS and ECMWF generally agree on a new low forming over the northern Gulf with a similar southeast track as the last storm, but the CMC is not as much on board with this idea. By the end of the forecast period Wednesday, the models agree best on the placement of a building upper ridge axis over mainland Alaska, but differ considerably across the North Pacific and the Bering with shortwaves emerging from eastern Siberia. The WPC fronts/pressures forecast was primarily derived from a CMC/ECMWF/GFS blend for the weekend, followed by an increase of the EC/GEFS means early next week with about 70% ensemble means by Wednesday. ...Weather/Hazards Highlights... For the weekend, the southeast Panhandle will likely get some heavy coastal rain and inland/mountain snow, from a combination of lingering moisture from a weakening short-range storm and the upstream low expected to be offshore by Saturday. Passage of a cold front progressing southward over the mainland behind the Friday-Saturday system may lead to a period of strong gap winds over some areas in the southern coastal areas. The next system in the series will likely produce a broad area of precipitation across the Bering Sea/Aleutians during the weekend, with some of this moisture likely to reach the southwestern half of the mainland by Sunday. Confidence remains limited on the details of precipitation coverage and intensity at this time due to uncertainty on the position and track of a surface low. How much moisture reaches the Panhandle on Monday will be dependent on the exact track of low pressure emerging over the Gulf. There will likely be another frontal system over the Aleutians/Bering Sea early next week and some of the precipitation could reach the far western mainland. The gradient between the front and high pressure departing into northwestern Canada may lead to some brisk winds, but again with low confidence in specifics at this time. High pressure building across the North Slope during the weekend should lead to a colder trend over most of the state from Friday through Sunday, with central areas most likely to see the greatest below normal anomalies. Then the eastward shift and amplification of upper features should bring a warming trend to above normal temperatures over western areas for early next week. Hamrick/Rausch Hazards: - High winds across portions of southern mainland Alaska, Fri-Sat, Nov 25-Nov 26. 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