Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 751 PM EDT Mon Sep 18 2023 Valid 12Z Fri Sep 22 2023 - 12Z Tue Sep 26 2023 ...Guidance Evaluation/Preferences... The 12Z model guidance suite is initially in fairly good agreement late in the week, with some timing differences already apparent with the storm system entering the Bering Sea region from eastern Siberia. The 18Z GFS and its ensemble mean are on the faster side of the guidance here. The CMC has trended more in line with the model consensus compared to yesterday with the low entering the Bering Sea by Saturday, so a solution between the ECMWF/GFS and some of the CMC was favored. However, the CMC is much stronger than the model consensus with the development of the Gulf of Alaska trough/low by the weekend, so a slightly less amplified solution seems to work best for that area. The use of the ensemble means increased to about 50-60% by early next week owing to increased uncertainty. ...Pattern Overview and Weather/Hazards Highlights... Periods of rain will likely be ongoing across southeastern Alaska on Friday with a deep surge of moisture from an atmospheric river event directed towards the southern Panhandle region, although the event should be abating by this time with the heaviest rainfall on Thursday. Attention then turns to the strong low pressure system entering the Bering Sea region by Friday and then reaching the western mainland by late Saturday. This will likely produce gale force winds over the coastal waters and an increase of rain and higher elevation snow for portions of western Alaska for the upcoming weekend. A third low pressure system is likely to develop over the Gulf by Sunday/Monday and bring increased chances for additional rain and wind for southern portions of the Panhandle region. In terms of temperatures, temperatures should generally be near to slightly above average for much of the mainland, equating to highs from the middle 40s to middle 50s for most locations, and slightly colder for locations north of the Brooks Range. Hamrick 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