Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 639 PM EDT Fri Mar 19 2021 Valid 12Z Tue Mar 23 2021 - 12Z Sat Mar 27 2021 ...Stormy pattern for Alaska next week... ...Guidance/Uncertainty Assessment... Guidance offers much better than average agreement for the pattern evolution and significant features for much of the next week's expected stormy pattern. The Day 4-6 (Tuesday-Thursday) forecast was primarily derived from a composite blend of well clustered guidance of the 12 UTC GFS/ECMWF/Canadian/UKMET models and 19 UTC National Blend of Models. Forecast spread increases gradually into days 7/8 when a composite of the best compatible 12 UTC GFS/ECMWF and GEFS/ECMWF ensemble means was mainly used along with the NBM. Composites tend to mitigate the less predictable smaller scale differences. WPC continuity is well maintained with this forecast methodology in a pattern with above normal predictability overall. ...Weather/Hazards Highlights... A lead northern Gulf of Alaskan storm will bring increasing moisture to the southern coast and especially the Panhandle next Tuesday into Wednesday where there is the highest potential for terrain enhancing heavy precipitation given the lower-latitude origin of the moisture. A main storm track out from northeast Russia will bring a series of deepened lows and frontal systems across the Bering Sea/Strait that are expected to take aim on the mainland next midweek and possibly again later next week into next weekend. These storms will be accompanied by organized wrapping precipitation and strong winds. Activity is slated to create unsettled maritime conditions over the Bering Sea before reaching mainland coastal areas and inland across the northwestern and western mainland along with periods of enhanced snow and winds. Downstream energy transfers underneath across Southwest Alaska and the Alaskan Peninsula next midweek and later next week with these systems will meanwhile favor northern Gulf of Alaskan cyclogenesis with renewed chances for organized southern and southeast Alaska precipitation. Schichtel Hazards: - No significant hazards are expected over Alaska during this forecast period. 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