Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 653 PM EST Thu Nov 23 2023 Valid 12Z Mon Nov 27 2023 - 12Z Fri Dec 1 2023 ...Synoptic Overview... An upper ridge axis is expected to extend from western British Columbia to the eastern Alaska mainland for much of next week, and thus keeping temperatures generally above late November averages across most of the state. A broad upper level gyre is expected to reside across the Bering Sea region through early in the week, before gradually moving eastward towards the western coast and weakening, following by another broad upper low vortex across the Bering by next Thursday. Meanwhile, a storm system will likely develop in the general vicinity of the Alaska Peninsula sometime around midweek and bring a renewed round of organized precipitation, with perhaps another storm system to close out the work week over the central Gulf. ...Guidance Evaluation and Preferences... The 12Z model guidance suite features good overall synoptic scale agreement to begin the forecast period on Monday. Going forward to Tuesday and Wednesday, timing differences become apparent with shortwave perturbations crossing south of the Aleutians, with the main difference being a faster trough progression in the CMC followed by a much stronger ridge axis building in behind it south of the Aleutians that loses support from the other guidance and even becoming out of phase, so the CMC was not used during this forecast period. The GFS becomes stronger with the low pressure system developing over the Gulf region by late in the period, but still reasonably close to the ECMWF in terms of overall placement. More model differences exist across the Bering Sea and Aleutians by next Thursday/Friday, and this is where forecast confidence is lowest. Ensemble means were gradually increased to about 50% of the forecast blend by Days 7 and 8. ...Weather/Hazards Highlights... The weather pattern will continue to remain active across southern coastal portions of the state Sunday into Monday, particularly from the Kenai Peninsula eastward to the northern portion of the southeast panhandle region, where sustained onshore flow will advect copious moisture inland and produce locally heavy coastal rain and mountain snow. There may be some abatement on Tuesday ahead of the next round of precipitation from the Alaska Peninsula to Prince William Sound for mid-week. Most of the Interior should be dry this weekend, but some snow showers are likely for southern and central portions of the state going into early in the week owing to warm air advection aloft. In terms of temperatures, highs are generally expected to be in the 20s to lower 30s for most inland areas, and 10s for the North Slope and lower-middle 40s for the southern coastal areas. There will likely be a return to colder weather by the end of the week, with some subzero lows expected for the normally colder locations in the Interior, and highs in the 0s and 10s for the northern half of the state. 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