Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 627 PM EDT Tue Sep 19 2023 Valid 12Z Sat Sep 23 2023 - 12Z Wed Sep 27 2023 ...Overview and Guidance Evaluation/Preferences... Upper pattern over the high latitudes during the medium range will feature a very strong (~175kt) upper jet exiting off eastern Asia late this week and arcing across the Aleutians into a broad trough well south/southeast of the Gulf of Alaska. To the north, troughing over northeastern Russia will slowly settle into the western mainland with leading weak/narrow ridging squeezed into northeastern Alaska. This favors rather quiet/typical conditions over much of the 49th state with the storm track near and south of 50N. The troughing digging into the northeast Pacific west of Washington will spur cyclogenesis and a fairly deep system (PMSL values nearing minimum values for this time of year per CFSR and ERA5 climo data around 48N/135W) but with only fringe effects for the southern Panhandle. 12Z guidance was in good agreement overall with expected timing/track differences in the handling of weaker waves along the baroclinic zone just south of the Aleutians. ECMWF was closer to the ensemble consensus (which was better than average) than the GFS, but neither was too far removed. This led to a multi-model/ensemble blend that trended toward increased ensemble weighting by next week (Days 6-8) for the surface progs. The 19Z NBM was a good starting point for the sensible weather grids. ...Weather/Hazards Highlights... With near to below average precipitable water values over nearly the entire state for this period, so will be precipitation for the period. Little to no rain/snow is expected over the majority of the interior/mainland, with light precipitation over the Aleutians eastward across coastal Southcentral. Rainfall will be more likely over the southern Panhandle as the deep system wraps up southwest of Haida Gwaii. Temperatures are forecast to be within several degrees of typical values for late September, with highs generally in the 40s/50s and lows in the 20s/30s. Fracasso No significant hazards are expected over Alaska during this forecast period. 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