Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 619 PM EST Sat Feb 17 2024 Valid 12Z Wed Feb 21 2024 - 12Z Sun Feb 25 2024 ...Stormy Pattern for Alaska next week... ...Guidance Evaluation and Preferences... 12 UTC GFS/ECMWF/UKMET/Canadian model solutions seem reasonably well clustered for Wednesday and Thursday in active flow and have good ensemble support, bolstering forecast confidence. The 12 UTC GEFS/ECMWF ensemble means seem best compatible with the 12 UTC GFS/ECMWF into later next week and next weekend. A favored composite maintains maximum system detail consistent with slowly lowering predictability in a steadily progressive and amplified pattern with energetic/windy storms driven by a strong upper jet slated to punch eastward from eastern Asia. WPC product continuity is reasonably good. ...Pattern Overview and Weather/Hazards Highlights... System energies lifting in a channel between a Bering Sea/Aleutians closed upper low/trough and a downstream upper ridge from western Canada up into a quite warmed Mainland will focus lingering heavy precipitation through next midweek from SouthCentral Alaska to northern Southeast Alaska. Near coastal rains and inland/mountain enhanced snows will be fueled by a long fetch atmospheric river with origin at low latitudes past Hawaii. This feed will steadily weaken into Thursday along with influence from this phase of the Bering Sea upper trough that shears/retrogrades away from the state. In this transition, unsettling trough energies/height falls will lift on the periphery of the upper ridge over the Mainland to offer periods with light to moderate snows blown by locally enhanced flow/gap winds. This transition will be prompted and lead into an increasing dynamic flow pattern as a powerhouse east Asian upper jet punches eastward across the northern Pacific toward Alaska around the base of a renewed and quite amplified new upper low/trough expected to work steadily into and settle over the Bering Sea and highly windy Aleutians mid-late next week into next weekend. This will stage unsettled conditions and foster large deepened low pressure systems over the Bering Sea as well as locally enhanced flow and periods of light to moderate precipitation on the eastern periphery up through Southwest and Western Alaska as impulses lift across the area. Meanwhile underneath, the potent upper jet and upper trough system energies will also work earnestly downstream next week, spreading a threat for high winds. This and associated surface based system development and track will enhance precipitation from the Alaska Peninsula/Kodiak Island through SouthCentral and Southeast Alaska later week into next weekend, increasingly working into an eroding lead upper ridge. The re-emerging heavy precipitation threat will be fueled by a long fetch plume, but this time with origins back across the northern Pacific into Asia. Schichtel 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