Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 754 PM EDT Sat Oct 24 2020 Valid 12Z Wed Oct 28 2020 - 12Z Sun Nov 1 2020 ...Guidance/Predictability Assessment... The forecast period begins on Wednesday with a lingering surface low over the northern Gulf of Alaska, and a surface high building over the Interior by the middle to end of the week. Meanwhile, an active weather pattern is likely for the Arctic Coast region with a couple of shortwave disturbances. Deterministic guidance indicates reasonable mass field agreement through Thursday night, and then normal levels of model spread become apparent. This holds true with the next and stronger storm system to pass south of the Aleutians, with the 12Z GFS considerably slower than the ECMWF/CMC and the ensemble means. By the end of the forecast period next weekend, a third system is forecast to approach the western Aleutians, with surprisingly better model agreement regarding location of the surface low, with the 12Z ECMWF faster than the model consensus, but not to the same degree as the 00Z run. The WPC fronts and pressures forecast was primarily derived from the 12Z CMC/ECWMF/EC mean, and with time increasing the weighting of EC mean along with some of the NAEFS mean. Some previous WPC continuity was also incorporated into the forecast. ...Weather/Threats Highlights.. Some lingering rain and mountain snow is expected across the southeast panhandle and portions of the southeastern Mainland through mid-week as the surface low over the northern Gulf gradually weakens, with onshore flow to the east of the low. Some snow showers and gusty northwest winds are likely across the Arctic Coast region as a couple of disturbances pass north of the region. Very little in the way of snow is expected for the Interior as high pressure will govern the overall weather pattern. The coldest temperatures are expected to be across the east-central portion of the state, especially for the latter half of the forecast period where some sub-zero high temperatures will be possible. Depending on the track of the Aleutian storm system next weekend, strong winds may materialize across this region, although confidence in this remains limited for now. Hamrick 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