Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 626 PM EST Thu Nov 05 2020 Valid 12Z Mon Nov 09 2020 - 12Z Fri Nov 13 2020 ...Guidance/Predictability Assessment... Progressive and active pattern is still forecast for Alaska next week. Lead system will be in the exit phase on Monday with its surface low in the Gulf and front moving through the Panhandle. Consensus of the 12Z guidance sufficed there. To the west, a robust Bering system from the west will move eastward as the parent low moves northeastward toward the Gulf of Anadyr. GFS continues to be just different enough from the ECMWF/UKMET/Canadian that it was excluded from the blend, but was not necessarily unreasonable. 12Z GEFS mean was close to the GFS on timing and was not preferred initially. Deterministic models strongly suggest a surface wave along the front Tuesday along the Aleutians that will move into the Gulf early Wednesday, spreading another round of coastal rain and inland snow with windy conditions to Southcentral. Yet another system may follow along the Aleutians to the AKPen around next Thursday to the Gulf around next Friday. ECMWF and Canadian paired fairly well with theses systems but relied much more on the ECMWF ensemble mean and GEFS mean as it fell back into good agreement from its earlier fast bias. This maintained good continuity from the forecast 24 hrs ago aside from the surface wave on Tuesday over the central Aleutians/southern Bering (hinted at yesterday but uncertainty had been high in the details). Still believe there are details on which the models will not yet have a handle, so features in the day 6-8 period will likely shift around. To the north, weak troughing and ridging will settle towards troughing by the end of the week as a surface boundary slowly decays. ...Weather/Threats Highlights... System in the Bering Sea Mon-Tue will spread an area of precipitation and strong winds across the Bering Sea/Aleutians/AKPen/western coastal Alaska. Trailing surface wave could bring additional modest precipitation to the region as it becomes the main low into the Gulf, spreading coastal rain and inland snow across Southcentral. Lingering precip will slowly face from northwestern areas (Seward Peninsula area) as the old parent low dissipates. Next system across the Aleutians around Wednesday will bring a quick round of rain/snow to the region again, ending into the Panhandle around next Friday. Above normal temperatures are forecast to remain over much of the Interior (generally west and north of the Alaska Range) next week. By contrast, below normal temperatures are expected over the Panhandle and through portions of Southcentral. Fracasso 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 Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Nov 8-Nov 9. - High winds across portions of mainland Alaska, Tue-Wed, Nov 10-Nov 11. 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