Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 651 PM EST Thu Feb 29 2024 Valid 12Z Mon Mar 4 2024 - 12Z Fri Mar 8 2024 ...General Overview... An upper level ridge is expected to build over mainland Alaska to begin next week along with a noticeable warming trend, compared to the frigid conditions expected over the upcoming weekend. However, this ridge should break down some going into mid-week and colder temperatures return to western and northern portions of the state. Meanwhile, an organized low pressure system is forecast to track south of the Aleutians and then enter the northern Gulf towards the end of the week, and result in increasing chances of precipitation for the southern coastal areas and adjacent mountain ranges. ...Guidance Evaluation and Preferences... The 12Z model guidance suite, along with the 18Z GFS, have a decent overall handling of the upper level pattern to begin next week, although there are already some placement and intensity differences with the initial surface low crossing the Alaska Peninsula, with the 18Z GFS the strongest solution. The guidance agrees well on this initial low steadily weakening through Tuesday evening across the northern Gulf. A more complicated set-up emerges south of the Aleutians with a dual-low pressure system that may eventually consolidate into a main surface low, or remain two distinct surface lows upon entering the Gulf region. Ensemble dispersion is high with major timing and placement differences, especially across the eastern Gulf, going into the Thursday-Friday time period, with below average forecast confidence at this time given the complexity of the upper level pattern across the north Pacific. Model agreement is generally better across the mainland and there is agreement in height falls across much of the state late in the period. A multi-deterministic model blend was used as a starting point in the forecast process on Monday and about 20% ensemble means, and then up to about 60% ensemble means by next Friday owing to the highly uncertain surface low evolution over the Gulf region. ...Weather/Hazards Highlights... Enhanced precipitation is likely for the south-facing terrain of the Alaska Peninsula, Kodiak Island, and the Kenai Peninsula early in the week as the initial low pressure system advects moisture northward across these mountain ranges, mainly in the form of snow. There will likely be some abatement midweek before the next Gulf low brings additional snow to the southern mountains, and eventually the southeastern Panhandle by Friday, although many aspects of the forecast are likely to change. Over the past 24 hours, there has been a general trend for heavier snow and coastal rain during this forecast period, but not to the point of reaching hazardous level criteria. Some snow showers are also likely across western portions of the mainland for the first half of the week, and then mainly dry for areas north of the Alaska Range for the middle to end of the week. In terms of temperatures, a continued warming trend can be expected across most of the mainland through about Wednesday, although the Arctic Coast remains quite cold. A cold front crossing western mainland Alaska will likely bring readings back down to below average levels near the Bering Sea coast by the end of the week. 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