Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 629 PM EDT Sun Oct 09 2022 Valid 12Z Thu Oct 13 2022 - 12Z Mon Oct 17 2022 ...Mid-late week South-Central to Southeast Alaska Heavy Rainfall and Elevation Heavy Snow Threat returns into next weekend with Aleutians/Bering Sea to Gulf of Alaska Storm... ...Guidance/Predictability Assessment and Weather/Hazards Highlights... The 12 UTC GFS/ECMWF/UKMET/Canadian models are well clustered Thursday into Saturday and a composite blend seems to offer a good forecast basis. Forecast spread increases into next week, so included the compatible GEFS/NAEFS/ECMWF ensemble mean solutions with still useful model data to maintains max WPC product continuity. A vigorous closed low exiting through the Pole/high latitudes of the Arctic Ocean will favor lingering rotation of a series of progressive troughs underneath into the North Slope and Brooks Range into Thursday to offer some threat for enhanced coastal surf and erosion along with some modest Brooks Range snows. The pattern should also be quite cooled down over the Interior into south-central Alaska in the wake of system passages. Model and ensemble solutions strongly favor a similar pattern evolution aloft and highlight development of an amplified upper trough from the Bering Sea through the Aleutians and amplified upper ridging building over the central to eastern Gulf of Alaska leading into mid-later week. There is a good signal for the tapping of additional northern stream and mid-latitude Pacific system energy with long fetch moisture to fuel a renewed threat for multi-day heavy precipitation enhanced by topography into south-central to southeastern Alaska given an emerging flow channel to the state in between the upper trough/ridge couplet, albeit with slow eastward pattern translation over time with upstream system approach. There remains an above normal guidance signal in support of that system. That major storm will develop and track from the northwest Pacific through midweek to the Aleutians/southern Bering Sea then Southwest Alaska and the Alaska Peninsula/Kodiak Island later week. This storm is expected to strongly transition and reform over the Gulf of Alaska into next weekend along with mid-latitude influx to rejuvenate the wet pattern across south-central and southeast Alaska. This deep low also offers a wind/waves and enhanced rainfall threat into a region already having significant precipitation from the lead pattern/systems. 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