Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 651 PM EDT Sun Mar 21 2021 Valid 12Z Thu Mar 25 2021 - 12Z Mon Mar 29 2021 ...Stormy pattern for Alaska next week... ...Guidance/Uncertainty Assessment... This forecast cycle the model guidance showed above average agreement and clustering through about day 6. The upper level flow will initially be quasi-zonal but then the approach of digging shortwave energy will carve out a more amplified pattern toward next weekend and early next week. At 500 mb, the deterministic ECMWF/CMC/UKMET were well clustered and even the typical faster GFS showed some utility. The GFSP favored better than the current operational version, and the GFSP was included in the blend over the GFS. At the surface, several waves of low pressure will track through the region, mainly impacting the southern mainland and southeastern areas the most. The most active storm system looks to come day 6-8 with back to back lows. Aside from the typical model spread noise, there was decent agreement. However to mitigate the less predictable smaller scale differences during that time frame, the WPC blend utilized the ECENS/GEFS means and this resulted in a forecast blend that maintains forecast continuity. ...Weather/Hazards Highlights... A few storm systems are expected to bring unsettled to active weather to the area, particularly later in the forecast period. The first system at the start of the period will bring precipitation mainly to the western mainland before weakening/dissipating. This will be followed a stronger low impacting the southern mainland by late in the upcoming work week or early next weekend. A final system at the end of the period is likely to track across the Bering Sea into the western mainland early next week. The highest QPF amounts are forecast for the southern mainland and the southeastern areas. Temperatures are expected to at or above normal for nighttime lows for much of the upcoming period while highs generally range below normal for the southern mainland and southeastern areas with some above normal departures for the northern mainland. Taylor 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