Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 409 PM EDT Sun Sep 26 2021 Valid 12Z Thu Sep 30 2021 - 12Z Mon Oct 04 2021 ...Three Major Storms for Alaska over the next week... ...Guidance/Predictability Assessment and Pattern/Hazard Highlights... A very stormy pattern for Alaska and offshore waters continues and forecast predictability remains above average overall. However, despite a reasonably well clustered 500mb flow evolution in the models, vorticity interactions and phasing issues have led to more offshore surface low differences than was the case yesterday. I'd prefer to flip the script from yesterday and instead blend the model supportive and quite compatible GEFS/ECMWF ensemble means for the entire WPC day 4-8 forecast period for max consistency. WPC product continuity was well maintained in this manner in conjuncture with manual surface system modifications to ensure sufficient offshore storm depth/intensity consistent with a highly supportive and amplified upper flow evolution as a series of powerful closed lows/troughs work through the Bering Sea and into the Gulf of Alaska. A lead storm system will bring a threat of high winds/waves across the Gulf of Alaska into Thursday, allowing a southwesterly push of moisture to funnel especially into the Panhandle where rainfall amounts may be locally heavy in the valleys (and snow at the higher elevations). Meanwhile, a dangerous storm system digging/consolidating through Bering will robustly dig to bring high winds/waves along with an enhanced rain/snow to western then southwestern areas of the mainland. Into later next week as the system slams into the highly unsettled Gulf of Alaska, another round of potentially heavy rain/snow are expected for the Panhandle and coastal areas of south-central Alaska. Temperatures will overall generally be below normal for the period due to the continued troughing over much of the state. Farther upstream, powerhouse Typhoon Mindulle will start to recurve into the westerlies from the south of Japan by midweek. After that, the ensemble consensus takes the system to the northeast into/toward the trough to its north/northeast. A deep extratropical low associated with Mindulle is slated to track toward the southwest Bering Sea next weekend into early next week as a maritime and Aleutians heavy seas/wind/rainfall threat. Schichtel Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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