Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 553 PM EST Tue Dec 26 2023 Valid 12Z Sat Dec 30 2023 - 12Z Wed Jan 03 2024 ...Heavy Precipitation for Southeast Alaska into Saturday... ...Wet and stormy pattern from the Aleutians into the Alaskan southern tier heading into the New Year... ...Overview/Guidance Evaluation/Preferences... Expect an upcoming pattern to close out 2023 to be highlighted with amplified mean upper troughing over the Bering Sea and Aleutians and a blocky downstream amplified upper ridging from western Canada into the eastern mainland and up over the Arctic Ocean to the northwest of the state will generally hold into 2024. In this pattern the general storm track should hold from near the Aleutians and up across the Gulf of Alaska to the mainland where leading deep layered and longer fetch southerly to south-southeasterly moisture flow will be periodically directed into the southern coast and Southeast by a series of deepened storm systems. Quickly weakening system energies and additional Arctic flow impulse influx lingering into the Interior will meanwhile provide some local unsettled conditions in drier flow. Guidance offers a generally similar mid-larger scale pattern evolution into the New Year, but suffers from rampant smaller scale and flow embedded system differences and less than stellar run to run continuity issues. Accordingly, a blend of the 12 UTC GFS/ECMWF/Canadian/UKMET and especially 12 UTC GEFS/ECMWF ensemble means seems to best provide a forecast basis with reasonable detail and compromise system timing. This along with manual edits to emphasize systems with the best guidance signal has acted to maintain max WPC product continuity in a pattern with overall near average predictability. While individual storm systems have uncertain timing and detail, the overall wet pattern seems to have quite good predictability. ...Weather/Hazards Highlights... The expected flow pattern leads to some confidence in multiple inches of precipitation (coastal rains, with snow at higher elevations/inland) into Southeast Alaska and eastern South-Central associated with low pressure systems lifting Friday into Saturday. Showers may continue into the New Year, but should overall lose intensity as ridging builds over the region. Wet flow around additional systems approach the AK Peninsula/Kodiak Island region then South-Central New Years Eve/New Years Day with possibly heavy precipitation and gusty winds. Gale to storm-force winds are expected offshore, but colder air over interior Alaska could lead to periods of enhanced gap winds in favorable spots. This system should weaken quickly as it pulls north into Mainland Alaska, while at the same time, a much larger and stronger storm affects the Bering Sea/Aleutians and eventually again the AK Peninsula/southern Coast into a stormy early 2024. This will also include high wind/wave threats. Meanwhile, a significant warming trend will be happening across Alaska through the period. Temperatures across much of Alaska should warm to well above normal. 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