Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 451 PM EST Thu Dec 12 2024 Valid 12Z Mon Dec 16 2024 - 12Z Fri Dec 20 2024 ...Deep low to produce a high wind threat from the southern Bering Sea through the Aleutians into early next week... ...Overview/Guidance Evaluation/Preferences... The 12 UTC models seem reasonably well clustered into early next week. This includes a main deep low and high wind threat for the Aleutians and southern Bering Sea. However, given rampant cycle to cycle variances without clear resolve beyond early next week, suggest a switch to better compatible and consistent guidance from the GEFS/ECMWF/Canadian ensemble means at the cost of less predictable than normal individual system and impact detail, especially over a highly unsettled Gulf of Alaska. WPC manual adjustments will try to offset inherent weakening of a blending process to ensure sufficient maritime lows with favorable upper support. WPC product continuity will overall be best maintained with this strategy. ...Weather/Hazards Highlights... A deep Arctic air mass and associated 1035 mb or so high will build into the Yukon and interior north/eastern Alaska on Sunday. Temperatures at the surface could drop as cold as 35 below, with colder wind chills possible in the windier gaps. Temperatures will not be quite so cold as to be an extreme event. Further, as the cold air from the high reaches the gaps in the Chugach and northern Panhandle, predominant southerly flow over the Gulf should mitigate the gap winds some. The Arctic air will be short-lived, already moderating by Tuesday as a large low over the Bering approaches Alaska and upper ridging builds downstream over the mainland. High winds associated with this low are forecast over the Aleutians on Sunday and Monday, which will weaken but remain gusty as they move towards the Gulf of Alaska midweek. Terrain enhancing rain at the lower elevations and mountain snows are possible, but increasingly uncertain through Kodiak and the western Gulf of Alaska through the Kenai Peninsula as the low approaches on Monday and Tuesday, but trends seem more offshore. A secondary low developing east of the primary lows may spread heavy precipitation into the southern Panhandle in a about a week to monitor given possible snow potential. There will also be some threat for gap winds on the periphery of this low. Schichtel Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart at: The WPC Hazards Outline depicts these threats. 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