Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 503 PM EDT Sun Mar 28 2021 Valid 12Z Thu Apr 01 2021 - 12Z Mon Apr 05 2021 ...Guidance/Uncertainty Assessment... Yet another tough Alaskan forecast through medium range time scales. The 12 UTC GFS/ECMWF solutions seem reasonably well clustered and have good ensemble support for day 4/Thu. It goes downhill quickly from there with model solutions diverging due to upstream sensitivities in both the amplitude evolution and stream interaction without a clear signal for any singular solution, at least to me. For the just sent WPC 500mb progs, I used a guidance composite day 4/Thu and quickly transitioned Fri to a 50-50 GEFS/ECMWF ensemble mean blend out through day 8. The means have differences with stream interactions as well, but overall are decently compatible considering the rapidly increasing forecast spread and maintain much better WPC continuity than the models. ...Weather/Hazards Highlights... Lingering/uncertain upper trough support over the Interior may favor periods with unsettled/cooled weather to include some threat for locally heavy snows. Meanwhile, an amplified upper trough will dig over the central to eastern Gulf of Alaska into later week and next weekend. This will be periodically be reinforced by progressive/uncertain upstream energies and surface systems from an also unsettled Bering Sea that dig to the lee of an upper ridge building up through the Aleutians. This pattern should favor a mean surface low position over the northern Gulf of Alaska and a threat of high winds/waves and lead/favorable onshore flow to fuel periods with terrain enhancing precipitation over eastern southern and especially Southeast Alaska later week through next weekend. Schichtel 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