Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 303 PM EST Wed Nov 13 2019 Valid 12Z Sun Nov 17 2019 - 12Z Thu Nov 21 2019 ...Aleutians to Gulf of Alaska Stormy Pattern... ...Guidance/Uncertainty Assessment and Weather Highlights/Threats... Ensemble model guidance seems fairly well clustered this weekend with the overall pattern evolution and for the most part a number of potentially well-organized weather focusing systems. Unsettling mid-upper level troughing will hover from Southwest Alaska northeastward through the Interior/North Slope to the Arctic. Limited moisture and lift will support periods of snow for the region this weekend in gradually easing low level easterly flow. Lead multi-stream low/jet energies are meanwhile slated to work underneath toward southern/southeastern Alaska from the Gulf of Alaska. These systems pose a maritime threat, and the circulation is expected to wrap moisture onshore to sustain some threat of locally heavy precipitation for coastal areas and especially favored terrain early next week. A preferred composite solution of the latest models and ensembles seems to offer a reasonable basis for the effects associated with these systems. The main weather focus will then shift westward toward the Aleutians and southern Bering Sea by early next week and spread steadily toward southwestern and south-central Alaska into next midweek with advance of a series of deep lows. These systems should have closed upper low/trough support and may deepen enough to entrain some deeper lower latitude moisture. Expect a maritime and coastal threat for high winds/waves and heavy precipitation in a pattern with near average predictability. WPC progs used a blend of the GEFS/ECMWF ensemble means amid growing model forecast spread, but manually deepened the surface lows given favorable upper support and continuity. Schichtel/Tate 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 Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Nov 19-Nov 20. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Sun, Nov 16-Nov 17. - High significant wave heights for coastal portions of the Aleutians, Mon-Tue, Nov 18-Nov 19. 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