Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 535 PM EDT Sat Sep 14 2024 Valid 12Z Wed Sep 18 2024 - 12Z Sun Sep 22 2024 ...Dynamic Storm to Impact Southwest through Southern/Southeast Alaska into midweek... ...Guidance Evaluation/Preferences... Guidance still highlights a pattern with highly energetic and progressive flow with dynamic storms impacting Alaska. A composite of reasonably well clustered guidance of the 12 UTC GFS/ECMWF/UKMET/Canadian shows good system detail consistent with above normal system predictability and WPC product continuity for Wednesday/Thursday. Switched to a models/ensemble means blend Friday/next weekend. The models offer much deeper systems clustering in position around a more stable center point provided by the ensemble means. Manual edits will be applied to further deepen offshore storms. ...Weather/Hazards Highlights... Forecast confidence continues to rise through above average levels regarding the details for yet another major storm slated through the early through middle part of next week. Expect a deepened/potent low track through the Aleutians and southern Bering Sea into with earnest Southwest Alaska will also with downstream energy transfer reform over the northern Gulf of Alaska and track near/offshore the Alaskan southern tier, eventually and actively crossing Southeast Alaska later Wednesday into Thursday. This would focus the majority of precipitation to the southwestern mainland and southern to southeastern Alaska. This storm will again also produce widespread maritime threats of high winds and waves. Onshore, the WPC Hazards Outlook depicts an associated risk of high winds and coastal impacts from the Aleutians to Southwest Alaska and the Alaska Peninsula given dynamic system strength and speed. The pattern seems to remain favorable for additional storm systems upstream in this flow along with the potential tapping of Pacific system energy and longer fetch moisture inflow leading into next weekend. Predictability lowers to average for details, most the bulk of guidance agrees in the development/re-developments of a complex and deep/moist storm to work potently up into the Gulf of Alaska. This seems to favor widespread threats of enhanced winds/waves/rainfall and coastal impacts from the southern Bering Sea/Aleutians/northern Pacific into especially the Gulf of Alaska/Alaska southern/southeast tier for next Friday/weekend to monitor. Meanwhile to the north, lingering low pressure centering over the Interior along with the uncertain passage and digging of shortwave energies aloft over the mainland may support persistence of scattered light precipitation into next week in the wake of a highly energetic leading short range storm. Activity on the northern periphery of the next main Bering Sea storm through next midweek may also lead to some locally/terrain enhanced gusty winds and precipitation with passage. 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