Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 800 PM EDT Tue Oct 27 2020 Valid 12Z Sun Nov 01 2020 - 12Z Thu Nov 05 2020 ...Guidance/Predictability Assessment... Model guidance initially is in better good agreement with the compact low crossing the Aleutians into the Gulf of Alaska. However spread with the low in the Arctic and the low in the western Bering is enough to cause downstream phasing with the Low in the Gulf by the middle of the extended period, and continues through the end of the period. Even though this is occurring, the general synoptic pattern is handling well. Chose to maintain continuity by utilizing the 12Z ECWMF/GFS/CMC early with increasing amounts of the ensemble means in the later period. ...Weather/Threats Highlights.. A long duration of deep moisture will be directed onshore over parts of the southern Mainland and the panhandle. Several inches of rain could fall over the lower elevations with snow possibly exceeding a foot in the higher terrain through at least Sunday November 1st. The compact low crossing the southern Aleutians into the Gulf will have strong wind-driven rains over the region. There will be a brief lull before another occluded low pressure system tracks south of the islands. A robust polar low will pass near the north shore through Saturday afternoon which will likely lead to some coastal flooding and heavy freezing spray. Colder weather is expected across the northern and eastern portions of the Interior, with more sub-zero high temperatures likely by the second half of the forecast period. Campbell Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri-Sun, Oct 30-Nov 1. Additional 3-7 Day Hazard information can be found on the WPC medium range hazards 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