Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 719 PM EDT Fri Sep 22 2023 Valid 12Z Tue Sep 26 2023 - 12Z Sat Sep 30 2023 ...Overview and Guidance Evaluation/Preferences... Deep troughing southeast of the Gulf of Alaska will favor ridging to its west and east to start the period, followed by a trend toward deeper troughing into the Aleutians from the northwest via the northern stream but mostly the southwest via a developing system in the mid-latitudes. The pattern has become a bit more unstable in the models, with the GFS/UKMET/Canadian favoring weaker/quicker systems later next week while the ECMWF favors a highly amplified pattern (due in part to a much stronger northern stream interaction with the mid-latitude flow out of the North Pacific). The ensemble means were roughly in the middle, though each tended to follow the parent model to a degree. The ongoing forecast favors at least some amplification late next week as the pattern over the rest of North America should retain modest meridional flow (in line with the multi-day means and from the CPC D6-10 forecast). This still favors a generally drier pattern to start with near normal temperatures. Though a multi-model consensus was used to start the forecast period, this quickly transitioned to a ECMWF ensemble mean majority blend in order to keep some semblance of continuity until further guidance dictates otherwise. The 19Z NBM was a good starting point for the sensible weather grids, but with a bit more weight toward the latest ECMWF ensemble mean. ...Weather/Hazards Highlights... Little to no rain/snow is expected over the majority of the interior/mainland this period, though the central/southern Panhandle could see modest rain Tuesday as the weakening low near Haida Gwaii lifts northwestward near and just offshore the coast. Given the forecast for a defined system to approach the Aleutians in some fashion late next week, light to modest or perhaps some heavier rain is possible there. This would spread into southwestern Alaska next weekend. 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, but cooler along the North Slope where temperatures have a higher probability of being above normal. 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