Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 642 PM EST Fri Nov 17 2023 Valid 12Z Tue Nov 21 2023 - 12Z Sat Nov 25 2023 ***High winds and heavy precipitation expected for south-central Alaska early next week*** ...Synoptic Overview... A large Arctic surface high will be slowly exiting the state early-mid next week. An incoming strong low pressure system from the North Pacific is progged to enter the central Gulf by Tuesday, and this will create a very steep pressure gradient across the south-central and southeast portions of the state, particularly near the coast, generating very windy conditions and an onslaught of deep maritime moisture towards the coastal mountain ranges. By Wednesday, this low weakens and a stronger second storm system crosses south of the Alaska Peninsula and towards the Alaska Peninsula by the end of the week, bringing more inclement weather to the region, and strong winds for portions of the Aleutians. ...Guidance Evaluation and Preferences... The 12Z model guidance suite is generally in good overall synoptic scale agreement, with the exception of the GFS that is displaced to the north of the model consensus with the Gulf low early in the week. Looking ahead to the end of the week, the GFS is northwest of the consensus with the next low pressure system near the central Aleutians, but close enough to be a plausible solution. The greatest degree of model spread is across the western Bering and Aleutians with the next system to affect the region. A general model blend, more focused on the ECMWF/UKMET/CMC, was used through mid-week, followed by gradually increasing percentages of the ensemble means going through Saturday. ...Weather/Hazards Highlights... A high impact weather event is looking increasingly likely for south-central portions of the state on Tuesday and into Wednesday as a potent surface low tracks northeastward into the Gulf. The 1040+ mb high over western Canada will create quite a pressure difference, and this will generate strong east to southeast winds across the northern Gulf and the coastal areas, with gusts into the 45-60 mph range possible and extremely rough seas. Additionally, strong onshore flow from the Alaska Peninsula to the Chugach Mountains will hammer this region with very heavy precipitation during this time, although models have trended a little lower compared to yesterday's guidance. Several feet of snow is likely for the higher elevations, and 3-6 inches of a cold rain for portions of the coast. More bad weather is possible later in the week as well, but this will be dependent on the eventual track and intensity of the second Gulf low. In terms of temperatures, a frigid start to the week across the Interior is forecast to modify some going into midweek as the Arctic high slides southeast away from the state. Milder air will likely be the case for the south-central portion of the state with more onshore flow and maritime air mass influence. 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