Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 611 PM EST Tue Nov 05 2024 Valid 12Z Sat Nov 09 2024 - 12Z Wed Nov 13 2024 ...Overview... The weather pattern will feature Arctic high pressure and progressive low pressure systems moving across the North Pacific to the Gulf of Alaska. Initially, a remnant low and occluded front from an earlier system will stall along the the coast of Southcentral and Southeast Alaska and will dissipate by Sunday. The next low pressure system will quickly move into the Gulf of Alaska over the weekend, then weaken as it approaches the coast by Monday. A third system will move into the Gulf of Alaska early next week and approach Southeast Alaska by mid-next week. These low pressure systems will be impactful for the Gulf waters, producing gale to near storm force winds, and may also bring moderate precipitation and gusty winds to portions of Southcentral and Southeast Alaska. ...Guidance Evaluation/Preferences... The WPC medium range forecast blend was composed of the best clustered guidance from the 12Z ECMWF/UKMET and GEFS/ECENS ensemble means, which showed the best agreement on timing and strength of low pressure systems affecting the Gulf of Alaska. These ensemble means, and to a lesser extent the Canadian ensemble mean, supported the deterministic solutions from the ECMWF and UKMET. The WPC blend weighted the deterministic model solutions higher for the first 3 days (Saturday through Monday), after which the ensemble means were given more weight amid steadily increasing uncertainty at longer time frames. This blend maintains WPC continuity from the previous forecast cycle. Manual adjustments were applied to offshore low pressure systems to ensure significant depth consistent with favorable upper level support and to offset weakening inherent in the blending process. ...Weather/Hazards Highlights... The active and progressive weather pattern will feature multiple Pacific systems moving across the Gulf of Alaska, which will produce hazardous conditions over the Gulf waters and near the Aleutians in the vicinity of the low tracks. The low pressure system that will be in the Gulf this weekend is forecast to produce gale force, and potentially near storm force, off the Aleutians and over the Gulf as it tracks east. Depending on the exact low track, gale force winds with this system may spread north to Kodiak Island as well. This system will also bring moderate precipitation chances to Southcentral Alaska and moderate to locally heavy precipitation to Southeast Alaska. The next system entering the Gulf of Alaska early/mid next week is forecast to be a little weaker than the first system, but will still bring another chance for gale force winds across the Gulf waters and Aleutians next week. This system will also bring another round of moderate precipitation to portions of Southcentral and Southeast Alaska. Models have been hinting at on an Arctic low developing off of northeastern Asia/Russia and nudging its way into the Bering Sea mid-next week. Arctic high pressure will likely steer this low south towards the Aleutians during the second half of next week. Arctic high pressure will remain in place through the forecast period, and will be responsible for maintaining mainly dry, cool weather across most of Mainland Alaska. Temperatures across the mainland will be near average through the weekend, then gradually dip below normal into next week, continuing a cooling trend. Dolan/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