Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 646 PM EDT Mon Oct 26 2020 Valid 12Z Fri Oct 30 2020 - 12Z Tue Nov 3 2020 ...Guidance/Predictability Assessment... The forecast period begins on Friday with a strong storm system passing just south of the central Aleutians and a compact low approaching the Arctic Coast region. The deterministic guidance indicates above average mass field agreement for Friday and into the weekend, given the increasingly amplified pattern in place. The 00Z ECENS becomes more progressive overall compared to the generally slower 12Z model guidance suite, with the 12Z ECENS slower and closer to the other guidance. By Sunday and Monday, another system is forecast to approach the western/central Aleutians, with the 12Z ECMWF slower than the GFS/GEFS, and the CMC to the southeast of the consensus. There has been an overall slower trend in the past 48 hours of model runs with the storm systems across the north Pacific. The WPC fronts and pressures forecast was primarily derived from the 12Z GFS/ECWMF/CMC for the first half of the forecast, and with time increasing the weighting of the GEFS mean and some of the EC mean. Some previous WPC continuity was also incorporated into the forecast. ...Weather/Threats Highlights.. Heavy rain and mountain snow will likely be making weather headlines across the southeast panhandle region as a potential atmospheric river event sets up to the east of a northern Gulf low. The potential exists for several inches of rain for the lower elevations as a result of the onshore flow, and at least a foot of snow for the higher elevations in this region. A wind-driven rain is looking more likely for portions of the Aleutians for Friday as the strong oceanic storm passes near or just south of this region, and again early next week in association with the next occluded surface low that passes south of the islands. The weather should also be noteworthy for the Arctic region with a well-developed polar low passing near the Arctic Coast through Saturday afternoon. There will likely be a period of gusty northwest winds over mainly ice-free water, and this may lead to some coastal flooding and heavy freezing spray. In addition, 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. Hamrick Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri-Sat, Oct 30-31. 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