Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 305 PM EST Mon Dec 03 2018 Valid 12Z Fri Dec 07 2018 - 12Z Tue Dec 11 2018 ...Guidance Assessment... Latest model run-run consistency and compatabilty with respective ensemble means is well below normal days 4-8. Ample forecast spread/uncertainty has led to main derivation of the WPC Alaskan medium range product suite from the 00 UTC ECMWF ensemble mean and to a lesser extent the 06 UTC GEFS mean. This solution was collaborated with local NWS Alaskan forecast offices and provides good WPC forecast continuity in a chaotic and transitional pattern. ...Pattern Overview and Weather Highlights/Hazards... The WPC Alaskan medium range period begins with an amplified upper ridge extending from the southeast panhandle to the Interior. This feature will likely gradually weaken over the next week, but there is much higher than normal forecast spread with the mechanism for this as the GFS/ECMWF in particular differ with with northern stream trough energy intrusion into the Interior and Bering Sea. The GEFS/ECMWF ensemble means are in better agreement in showing eventual mid-upper level trough development through the Bering Strait/Sea and over the northwest and western Interior. This compromise solution would support cold air advance into the Interior, but with more limited potential into the southern Alaskan tier as buffeted by maritime onshore fetch. This moist fetch will fuel heavy precipitation into the entire southern Alaskan tier as deep systems develop underneath into the Gulf of Alaska, with a lead deepened low expected to reach Kodiac Island and the Alaskan Peninsula Friday before gradually weakening next weekend. Additional stormy conditions/heavy precipitation are also on tap for maritime interests and inland into the southwest/southern/southeastern Alaskan tiers in a protracted wet pattern fueled into next week by additional system genesis potential. There is also a decent signal in guidance to bring a deep low generally eastward toward the Aleutians and southern Bering Sea days 6-8 that has potential to become a significant storm. Schichtel WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can be found at: http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html