Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 716 PM EDT Mon Oct 23 2023 Valid 12Z Fri Oct 27 2023 - 12Z Tue Oct 31 2023 ...Synoptic Overview... The main feature for the extended forecast period through Saturday will be an anomalous and large upper ridge/closed high centered near the southern mainland coast, likely reaching 576 dm. It will serve as a blocking feature through the end of the week before gradually eroding, keeping most of the mainland dry. Some changes are on the horizon by late Saturday with a low pressure system originating from the Kamchatka Peninsula that'll head in the general direction of the southern Bering and the central Aleutians by late Friday, and should be strong enough to displace the ridge axis some to the southeast, closer to the southeast Panhandle region. This storm system would increase the prospects for precipitation across western Alaska and the Aleutians, also with some gusty winds. ...Guidance Evaluation and Preferences... The 12Z model guidance suite has a good overall depiction of the synoptic scale pattern across the Alaska domain for the end of next week, and therefore, a nearly multi-deterministic model blend suffices as a starting point in the forecast process for Friday. Going into the second half of the forecast period, the greatest model differences are generally located over the Bering Sea and the Arctic, and the best agreement with the upper ridge axis near the southeast Panhandle region. There is a gradual increase of the ensemble means going into early next week, accounting for about half of the forecast blend by that time, with a little more weighting to the 12Z GEFS mean compared to the 00Z ECENS. ...Weather and Hazards Highlights... Temperatures across the state are expected to range from the mid 20s to near 40 degrees for highs across most inland areas, and lows generally from the mid 10s to near 30 degrees, locally colder in the normally colder sheltered valley locations. Temperatures will also be highly dependent on whether valley inversions can mix out during the day. Highs in the 40s and lows in the 30s are generally expected for the southern coastal areas. The highest QPF is expected for the upslope terrain of the Alaska Peninsula and the eastern Aleutians where moisture advection from the North Pacific will be sustained the longest. Mainly light precipitation is expected for the western portions of the Interior. Moderate to locally heavy snow is possible for portions of the western Interior, and even some instances of freezing rain will be possible. 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