Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 PM EDT Sat Mar 27 2021 Valid 12Z Wed Mar 31 2021 - 12Z Sun Apr 04 2021 ...Guidance/Uncertainty Assessment... The 12 UTC GFS/ECMWF/UKMET, the 12 UTC GEFS mean, the 00 UTC ECMWF ensemble mean and the 19 UTC National Blend of Model solutions are reasonably well clustered day 4/5 (Wed/Thu) and a composite blend seems to provide a good starting point for the forecast process in a period with above normal predictability. However, forecast spread increases dramatically at longer time frames as guidance seems quite sensitive to upstream feature effect on flow evolution and amplitude. Given rapidly rising uncertainty, the WPC Alaskan medium range product suite into days 6-8 (Fri through next weekend) was primarily derived from the still reasonably compatible GEFS/ECMWF ensemble means and the 19 UTC National Blend of Models. These blends maintain good WPC continuity in difficult flow. ...Weather/Hazards Highlights... Short range Bering Sea storm energies moderate over the mainland into mid-later week, but along with lingering upper trough support the pattern should favor a period with unsettled/cooled weather to include some threat for locally heavy snows. Meanwhile, an amplified upper trough will settle over the Gulf of Alaska and be periodically be reinforced by progressive/uncertain upstream energies and surface systems digging from an also unsettled Bering Sea/Aleutians. This may anchor a mean surface low position over the northern Gulf of Alaska and a risk of high winds/waves and lead/favorable onshore flow to fuel a threat for a prolonged periods with terrain enhancing precipitation over Southeast Alaska midweek into 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