Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 625 PM EST Tue Jan 19 2021 Valid 12Z Sat Jan 23 2021 - 12Z Wed Jan 27 2021 ...Overview and Guidance/Uncertainty Assessment... Upper ridging over the northeastern Pacific on Saturday will transition westward and southwestward next week, favoring troughing in the Bering Sea. Several shortwaves will be blocked over the Mainland and split either toward the Bering Strait and/or into the Gulf. The models/ensembles showed reasonable agreement to start the period this weekend, but then diverged in timing/amplitude. Lead system will sink southeastward Saturday out of the Gulf as the first Bering system moves northeastward past the Dateline by Sunday. Blend of the 12Z GFS/ECMWF/UKMET offered a good starting point. Thereafter, the guidance split between a quicker and slower cluster. The quicker models included the GFS/Canadian and most GEFS/CMC ensembles. The slower camp included the 12Z ECMWF/UKMET and most ECMWF ensembles. The slower camp was preferred due to the fairly strong, though transient, ridging downstream Monday over the Gulf as well as upstream over the western Pacific. Continuity was on the slower rather than quicker side as well. However, utilized the 00Z ECMWF ensemble mean fully by later in the period as it was not as slow as the 12Z ECMWF. This would slow the system on Sunday in the Bering and allow for a surface wave to develop but eventually split to the southeast as it system tries to maneuver through the upper ridge in weakened fashion around next Tue. Next Bering system would move into the central part of the Sea by next Wed per the ECMWF ensemble mean (and actually the 12Z GEFS mean as well). ...Weather/Hazards Highlights... Gulf system on Sat will bring light to modest precipitation to areas of the Panhandle and far southeastern Alaska as it slips southeastward. Bering system on Sunday will bring breezy conditions and light to modest precipitation to the Aleutians, enhanced around the wave along the front where precipitation could be heavy (more than one inch). This could spread along the western coast of Alaska as the front pivots and redevelops to the southeast, across the AKPen, late Mon into Tue. Next system could spread additional rain/snow to the Aleutians Tue-Wed next week, along with windy conditions as the guidance shows potential for a modestly deep system. The majority of the state will see above to much above normal temperatures this weekend, with the most extreme anomalies likely to be over northern and western areas. Temperatures should cool back toward more typical late January values next week. The Panhandle may see a larger area of below normal readings after the weekend system departs and offshore flow increases. Fracasso Additional 3-7 Day Hazard information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php No significant hazards are expected over Alaska during this forecast period. 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