Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 655 PM EST Sat Jan 27 2024 Valid 12Z Wed Jan 31 2024 - 12Z Sun Feb 04 2024 ...Heavy precipitation and high winds for southern Alaska should wane early next week as bitterly cold temperatures across the interior are expected to moderate some... ...Overview... An upper trough stuck over Alaska should finally begin to shift eastward with time around the middle of next week as upper ridging builds over the Bering Sea and eventually shift into Alaska. This should help to moderate bitterly cold temperatures across much of the Interior as well as ushering in a drier overall pattern. Upper troughing over the Gulf Wednesday-Thursday though will continue to support some lingering rain and gusty winds across Southeast Alaska as a surface low tracks south of the Panhandle. Another storm system looks to approach the western Aleutians by late week or next weekend bringing increased precipitation chances. ...Guidance Evaluation/Preferences... Initially, models suggest elongated west-east troughing from far eastern Siberia into northern Alaska should split as an upper ridge builds over the Bering Sea. This should shift an upper low across northern Alaska Thursday-Friday and eventually into the Arctic next weekend. Upper troughing should progress across the Southern Coast/Gulf Wednesday-Thursday. Compared to yesterday, there is better agreement on the overall evolution of this, but the CMC does continue to be an outlier in suggesting some sort of cut-off weak low near the Southeast before the upper ridge shifts into the region. The early period WPC forecast blend was able to utilize a purely deterministic model blend, but with greater emphasis towards the more agreeable 12z GFS/ECMWF (which had better consensus with the ensemble means). Meanwhile, the western part of the elongated trough should drop south towards the Bering and interact with a broad upper low/trough moving towards the region. There greatest forecast uncertainty of the period resides with individual shortwaves/surface lows rotating around this broad trough. There is a lot of noise late in the period on the placement, track, and strength of surface lows near/crossing the west and central Aleutians. These sort of systems have relatively low predictability at these time scales, so it seemed prudent to lean more on the ensemble means late period until there's a better consensus. Did continue to maintain small contributions from the ECMWF and GFS in the forecast blend just for a little bit of added definition to the overall pattern as the ensemble means wash out the detail. ...Weather/Hazards Highlights... By the start of the forecast period (Wednesday), heavy rainfall across the Southeast and Panhandle should be waning, but some lingering precipitation should continue into Thursday as a deep surface low slides south of the Panhandle and general troughing in the Gulf slides eastward. Some gusty gap winds could continue as well for Southern Alaska. Upper ridging moving into Alaska late week and the weekend will bring in much drier conditions across the Mainland. Systems near the Aleutians though will bring an increase in precipitation generally from west to east with cold front progression. Precipitation and some gusty winds could move into the Alaska Peninsula and possibly parts of the Southern Coast (and maybe far western Alaska) next weekend. Well below normal temperatures over the Mainland should be moderating and shifting east by the middle to latter part of next week, including Southeast Alaska. As the upper ridge moves into the region though, temperatures will warm to above normal Friday and especially next weekend across Western Alaska, the Aleutians, and the North Slope. Daytime highs along the Western Coast and North Slope could be 10-20+ degrees above normal, which would be a strong contrast compared to this weekend. Santorelli 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