Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 617 PM EDT Mon Sep 26 2022 Valid 12Z Fri Sep 30 2022 - 12Z Tue Oct 04 2022 ...Heavy rainfall for portions of the Panhandle this week... ...Strong storm likely in the Bering Sea near the Aleutians Friday-Saturday... ...Synoptic Overview and Weather/Hazards Highlights... Amplified pattern into the medium range will be exacerbated by the extratropical transition of T.S. (and likely future Typhoon) Kulap in the West Pacific current southeast of Japan. Working in tandem with strengthening upper ridging over northwestern Canada, this will support a robust and deep area of low pressure moving through the Bering Sea late this week into the weekend before progressing (but weakening) into the Gulf. Modest to perhaps locally heavy rain (and high elevation snow) is possible over coastal Southcentral into the Panhandle with a lead system and following wave of low pressure. The Bering system will provide strong winds over the western Aleutians and modest rainfall, with a shift into coastal Southcentral (southeast Kenai eastward) as the low moves through the northern Gulf. Temperatures will be near to above normal over central/northern areas but near to below normal over southern areas. ...Guidance/Predictability Assessment... Guidance still showed poor agreement in the extratropical transition of Kulap, but a position between the quicker GFS and slower ECMWF was near the last JTWC point at Tau 72. By the time the system reaches the Bering, the 00Z ECMWF ensemble mean was nicely in between the two deterministic models (with support from the 12Z UKMET) and was the preference thereafter. Farther downstream, the GFS has trended slower/more closed off with a sharp trough and closing low well south of the Gulf that supports a lingering front near the Panhandle and a slower approach of a sfc wave (like the ECMWF-led camp 24 hrs ago). However, there was still a shift quicker overall in the northern stream portion to move the front eastward into Canada as the southern closed low lingers well south in the mid-latitudes. But, this kept reasonably good continuity. Back to the Bering... as the system translates into the Gulf, deterministic models showed less agreement and preferred to stay the course near continuity and the ECMWF ensemble mean with a track over the AKPen into the northern Gulf until/unless there is a trend one way or another. Another trailing system from the west could enter the Bering but an ensemble consensus near the ECMWF ensemble mean was preferred. Fracasso Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Thu-Mon, Sep 29-Oct 3. - Heavy precipitation across portions of the Alaska Panhandle, Thu-Fri, Sep 29-Sep 30. - High winds across portions of the Aleutians, Fri-Sat, Sep 30-Oct 1. 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