Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 524 PM EST Thu Feb 13 2025 Valid 12Z Mon 17 Feb 2025 - 12Z Fri 21 Feb 2025 ...Overview... An arctic upper low will initially be over northern Alaska by the start of the period on Monday with guidance showing better agreement this should slowly drift towards the northeast and lift north of the state by Tuesday. Meanwhile, a more active pattern emerges south of the Aleutians early to mid week with a couple additional low pressure systems tracking east towards the Aleutians, Alaskan Peninsula, and Gulf regions. This will provide a consistent onshore flow pattern, particularly from Kodiak Island to the Southeast, with periods of possibly heavy rain and mountain snow expected. Over the mainland, a weak ridge axis extends from western Canada to central Alaska, with generally above average temperatures expected across most of the state. ...Guidance Evaluation and Preferences... Model guidance shows better agreement on the upper low over the Arctic early in the period, with the 12z run of the ECMWF finally trending towards the consensus of the core of the low lifting northward by mid-week. The greatest focus for uncertainty during the period though continues to be with individual shortwaves/surface lows embedded within a broad trough near/south of the Aleutians. There continues to be a lot of run to run inconsistencies regarding the timing, track, and intensity of such lows and this lends to a very low confidence forecast at this time. The one outlier, at this time, was the 12z GFS which was different in the beginning of next week with a low(s) near the eastern Aleutians/AK Pen region. Much of the guidance was showing a couple of low pressure areas south of and near the Aleutians, but the 12z GFS showed one consolidated low. As such, the early week WPC blend did not include the GFS, and was instead weighted towards the 12z ECMWF which showed the best consistency with the ensemble means. The mid to late week blend trended much heavier towards the ensemble means to help with the operational model noise. ...Weather/Hazards Highlights... A series of low pressure systems, albeit with a lot uncertainty, will impact parts of the Aleutians to the Southern Coast and eventually Southeast Alaska through the period. Moderate to heavy rainfall is possible, with a focus right now on the Kenai Peninsula/southern Coast region. In higher elevations, heavy snow may be a concern as well. Periods of gusty winds, depending on exact low track, are possible. Consistent onshore flow throughout the medium range period though will continue the overall wet pattern. A weak front across the Mainland may also support some light showers next week, but otherwise the interior parts of Alaska should be mostly dry. An upper ridge over much of the mainland should support increasingly warmer temperatures next week. Initially, parts of northwest and northern Alaska though will be below normal before the Arctic upper low lifts out of the region by mid week. 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