Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 656 PM EST Sun Jan 28 2024 Valid 12Z Thu Feb 01 2024 - 12Z Mon Feb 05 2024 ...Bitterly cold temperatures across the Mainland will quickly rebound to near or above normal by the weekend... ...Overview... Upper troughing over Alaska should shift east with time as a block upper ridge builds in upstream and shifts over the Mainland by the weekend. This should help moderate bitterly cold temperatures across much of the Interior as well as usher in a drier overall pattern. The exception to this may be across the Aleutians/Southern Coast as a couple of storm systems impact this region sliding underneath the upper ridge as the Bering Sea becomes active again. ...Guidance Evaluation/Preferences... The latest 12z models and ensembles show pretty good agreement on the overall large scale pattern, but plenty of variability in the small scale details, especially late period near the Aleutians. Models suggest energy from initial troughing over the Mainland on Thursday, may cut off over the Gulf briefly before quickly ejecting inland over northwest Canada. The 12z GFS is a notable outlier here keeping a closed low out over the Gulf through next weekend. There isn't much support for this outlier solution at this point, so it was not favored in the WPC forecast blend for today. Meanwhile, multiple shortwaves/surface lows look to rotate around a large stationary upper low generally centered over the Kamchatka Peninsula through much of the period (though may eventually slide south towards the far western Aleutians late period). There is growing consensus that a pair of surface lows should cross the island chain Thursday-Saturday, with model agreement for the second system to have a relatively deep central pressure in the mid-upper 960s. This should weaken over the weekend as additional weaker systems cross into the western domain, but there is increasing variability on these very low predictability systems. The WPC blend for today leaned heavily on the 12z ECMWF given its better agreement with the ensemble mean guidance. Paired the EC with additional deterministic solutions through day 6, with increasing contributions from the ensemble means 7-8 to attempt to break down some of the uncertainty near the Aleutians late period. Overall, this maintained fairly good continuity with yesterdays forecast. ...Weather/Hazards Highlights... By the start of the forecast period (Thursday), heavy rainfall across the Southeast should be waning, but some lingering precipitation may continue into Friday as a deep surface low slides south of the Panhandle and general troughing in the Gulf slides eastward. Upper ridging moving into Alaska late week and the weekend will bring in much drier conditions across the Mainland overall. Systems near the Aleutians though will bring an increase in precipitation generally from west to east with cold front progressions with gusty winds possible depending on system strength. One deep system looks to show the best potential around Friday-Saturday with some moisture moving into the Southern Coast/western Alaska as additional energy moves into the Gulf next weekend. Well below normal temperatures over the Mainland should be retreating eastward across the Mainland by the middle to latter part of next week, followed by a warming period from west to east Friday and especially the weekend. By next Monday, parts of western Alaska and the North Slope could be 10-20+ degrees above normal, which would be a strong contrast compared to current temperatures. Southeast Alaska looks to stay near or below normal most of the forecast period. 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