Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 707 PM EDT Fri Apr 14 2023 Valid 12Z Tue Apr 18 2023 - 12Z Sat Apr 22 2023 ...Cold pattern for much of Alaska to ease next week... ...Overview... Upper lows/troughs over the Arctic Ocean, through the mainland and additionally over the Gulf of Alaska are expected to remain roughly sandwiched between upper ridges centered both to the west and east of Alaska, allowing a a blocky pattern to linger into next week. The recently stagnant/stable pattern may be interrupted by weaker waves embedded with the flow. There is a growing trend in support of pattern transition as ridging to the west of the state reforms into a closed high to center near the Bering Strait as heights slowly rise downstream over the mainland. This overall pattern will promote a dry and cold, but increasingly moderating period for most of the state over time, with most light to moderate precipitation set to linger from coastal South-central to Southeast Alaska as lobes wrap around a mean upper trough position. There is a risk of deeper than expected Gulf of Alaska low developments to monitor given potentially potent but quite uncertain energy interactions within the mean upper trough position. ...Guidance Evaluation/Predictability Assessment... Models and ensembles show a reasonably similar larger scale pattern into Tuesday/Wednesday. A 12 UTC GFS/ECMWF/CMC and GEFS/ECMWF ensemble mean blend seems to best mitigate flow embedded feature differences consistent with predictability. The 12 UTC UKMET offers a plausible but stark outlier deep Kodiak Island low by Wednesday. Applied most blend weighting increasingly from the models to the ensemble means over time to best maintain WPC product continuity in a pattern with below normal predictability along with a noticable westward low position trend over the Gulf of Alaska. ...Weather/Hazard Highlights... Upper troughing will focus much below normal temperatures over the mainland for especially the West Coast and western Interior into early next week as high pressure over the Bering shifts northeastward to the Beaufort Sea. It may take until next midweek for any appreciable moderation in temperatures over the mainland to be realized, though this period will at least be milder than the deep cold in the near term. Initially strong pressure gradient between the Bering high and the Gulf low will favor NW gap winds from the eastern Aleutians to the AKPen which may exceed 40 kts into early next week. Moderate precipitation will be mostly confined to the Southeast as weakening occlusions and surface troughs rotate around the mean parent low position over the east-central Gulf of Alaska, but guidance has trended farther offshore. The deepened lows present a maritime threat. Schichtel Hazards: - High winds for the eastern Aleutians and Alaska Peninsula, Mon, Apr 17. - Much below normal temperatures for the West Coast and western Interior Alaska, Mon, Apr 17. 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