Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 648 PM EDT Thu Oct 06 2022 Valid 12Z Mon Oct 10 2022 - 12Z Fri Oct 14 2022 ...Potent Bering Sea storm to impact Western/Southwestern Alaska Monday with a threat for high winds/waves and coastal flooding... ...Heavy rainfall and elevation heavy snow threat for South-central to Southeastern Alaska to return mid-late next week... ...Guidance/Predictability Assessment and Weather/Hazards Highlights... The 12 UTC GFS/ECMWF/UKMET solutions seem best clustered Monday into Wednesday and a composite blend seems to offer a good basis for the forecast that is well supported by ensembles. There is a high likelihood that this period will be highlighted by emergence of a powerful storm set to lift from the North Pacific into the Bering Sea before slamming into West/Southwest Alaska Monday. Guidance has trended much stronger with this dynamic system and that seems reasonable given upstream satellite signature/upper jet support. This system offers a maritime high wind/wave threat and lead enhanced precipitation/long fetch deep moisutre inland across western/southwest Alaska Monday along with a swath of wrapping high winds and a risk of coastal flooding. Later, individual system timing and emphasis differences remain more problematic through mid-late next week in amplifying flow. However, model and ensemble solutions still favor a similar patern evolution aloft into 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. There remains a decent signal to monitor for the tapping of additional mid-latitude Pacific system energy and long fetch moisture that could fuel a renewed threat for heavy precipitation back into south-central to southeastern Alaska given an emerging flow channel to the state in between the upper trough/ridge couplet. The WPC medium range product suite at these longer time frames was derived from the most compatible 12 UTC GEFS/NAEFS/ECMWF ensemble means. Manually adjustements were applied to blend output to mitigate some system weakening inherent to the blending process amid growing forecast spread and run to run model continuity issues. Upstream, there is also now an above normal ensemble guidance signal in support of yet another potent storm expected to track generally eastward from eastern Asia and the northwest Pacific early-mid next week to the Aleutians/southern Bering Sea in about a week. This deep low also offers a wind/waves and wrapping enhanced rainfall threat broadly along the path. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun, Oct 9. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Oct 11-Oct 12. - High winds across portions of mainland Alaska, Mon, Oct 10. - High winds across portions of mainland Alaska, Sun, Oct 9. 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