Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 658 PM EST Tue Dec 12 2023 Valid 12Z Sat Dec 16 2023 - 12Z Wed Dec 20 2023 ***Heavy Snow and coastal rain for south-central Alaska this weekend, and windy for the Aleutians*** ...Guidance Evaluation/Preferences... A general model blend of relatively well clustered guidance from the 12Z deterministic guidance was used as a starting point in the forecast process going into the weekend, along with a little previous WPC continuity. Going into early next week, there is still decent overall synoptic scale agreement on the main trough over the Bering and a ridge over western Canada, but there is more mesoscale uncertainty going into this time range, so a gradual increase of the ensemble means up to 40% by next Wednesday was incorporated. ...Weather/Hazards Highlights... The most active weather during this forecast period is expected to be across the southern coastal areas and extending western across the Aleutians. Heavy snow is likely for the coastal mountain ranges extending from the Kenai Peninsula eastward to the St. Elias Mountains for the upcoming weekend with moist onshore flow, and several feet of additional snowfall accumulation is likely for these areas. Right along the coast, there may be just enough warm air to support either a cold rain or a rain/snow mix, and this could also be heavy at times. Winds will likely be making weather headlines across the eastern Aleutians and the Alaska Peninsula going into early next week with a potent Bering Sea low pressure system developing and a strong pressure gradient south of it. Very high surf and possible coastal flooding are also hazards that could be realized. This same low will likely be associated with warm air advection snow across portions of the western mainland/Interior. Elsewhere, most of the northern and eastern mainland should remain dry and cold during this time. Hamrick 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