Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 717 PM EDT Mon Aug 30 2021 Valid 12Z Fri Sep 03 2021 - 12Z Tue Sep 07 2021 ...Pattern Overview and Model Guidance... Upper troughing over the Bering and southwestern areas will slip into the Gulf this weekend via two separate entities. Any ridging over eastern areas of the mainland will weaken into Canada after Friday as the flow becomes southwesterly aloft. Farther upstream over the East Siberian Sea, another upper low will slowly move toward the Bering Strait but with most of its focus over northeastern Russia. The models agreed overall on the evolution but the 12Z GFS strayed farthest from the generally good ECMWF-led agreement (with the Canadian mostly, and to a smaller degree the UKMET) and it was not used. In fact, differences appeared as soon as F24 south of the Aleutians which was unusual for such a short lead time. Other areas over the domain exhibited expected spread that increased with time, but the GFS remained just outside the ensemble agreement that included its own GEFS mean. Utilized the 12Z ECMWF most for a deterministic weight with an increased ensemble mean weighting (ECMWF + GEFS) by next week (Sun-Tue). ...Sensible Weather... Exiting system later this week will take its heavy rain threat into Canada with some lingering areas of at least modest rain near the area of low pressure near Haida Gwaii Friday and also over the eastern portion of the Kenai Peninsula. Subsequent system should bring in another round of light to modest rains for the Panhandle late Sat into Sun. For the rest of the state, troughiness will support a rather unsettled period with widespread light showers and snow at higher elevations as temperatures generally cool with time. Front moving into northwestern areas will support more organized rain/snow to the Seward Peninsula into the Brooks Range but likely still light to modest amounts. Additional enhancement is possible farther east as the front advances toward the Yukon. Temperatures will start the period within 5-10 degrees of normal (above normal over much of the Interior and below normal along coastal areas) with a trend toward cooler than normal temperatures from northwest to southeast next week. Temperatures in the 50s/60s will generally fall to the 40s/50s as the cold front moves through. Fracasso Hazards: - Heavy rain across the eastern portion of the Kenai Peninsula, Thu-Fri, Sep 2-Sep 3. 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