Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 728 PM EDT Tue Mar 21 2023 Valid 12Z Sat Mar 25 2023 - 12Z Wed Mar 29 2023 ...Overview/Guidance Evaluation/Predictability Assessment... The weather pattern remains active across the Aleutians and the Bering Sea for the weekend and also into next week, with the first storm system arriving late Saturday and into the Sunday, and the next potential storm next Wednesday/Thursday showing up on the distant weather horizon for the western Bering Sea region. Meanwhile, an upper level ridge will likely be in place across the Gulf after the departure of the eastern Gulf low by Sunday, and this will be in response to a gradually amplifying upper level pattern. This will tend to keep things quieter in the extended range across much of the southern mainland coast after multiple heavy precipitation events. The 12Z model guidance initially has a good overall synoptic scale depiction across the Alaska domain for the Friday to Saturday time period, although the CMC is a little more amplified with the trough over the Gulf of Alaska and it drops the low pressure center faster towards the southeast compared to the model consensus going though the weekend. The GFS becomes more amplified with its upper trough over the Aleutians and Bering Sea by Sunday and this results in a trailing surface low that does not have much support from the other guidance, but is otherwise comparable across other areas. Looking ahead to the first part of next week, the models handle the evolving amplified pattern better than a typical day 6 and 7 forecast, even though some differences remain regarding mesoscale features. Looking ahead to next Wednesday, the ECMWF/CMC/GFS are all signaling the potential for another low pressure system entering the western Bering Sea, so this will be something to monitor in the days ahead. A multi-deterministic model blend suffices as a starting point for Saturday, and then contributions from the GEFS and ECENS total up to 50% by next Wednesday. ...Weather/Hazard Highlights... The main weather story is expected to be the increase in snow and wind associated with the approach of the next Bering Sea low pressure system over the weekend. Heavy snow is likely for western portions of the Brooks Range where 1 to 2 feet of snowfall accumulation is possible from Saturday night to early Monday, along with blizzard conditions. Heavy snow is also increasingly likely for southern portions of the Seward Peninsula where greater than a foot of heavy wet snow is possible as well, except for coastal areas where more rain may mix in and keep snowfall totals lower. Rain is also likely for the lower elevations of the Interior on Sunday as highs reach into the middle 30s to around 40 degrees. High wind gusts on the order of 35 to 55 mph will be possible across coastal portions of western Alaska as a strong pressure gradient develops, and some coastal flooding may also be a problem. In terms of temperatures, expect readings to generally be running 10 to 25 degrees above late March averages for central and northern portions of the state for the weekend as deep southerly flow ahead of the Bering Sea low advects a much warmer maritime air mass across the Interior, with the potential for many inland areas reaching highs above freezing on Sunday, even including areas north of the Brooks Range. A return to more seasonal March conditions is likely by early next week as a cold front crosses most of the state. Hamrick Hazards: - Heavy snow across portions of western mainland Alaska, Sat-Sun, Mar 25-Mar 26. - High winds across portions of western mainland Alaska, Sat-Sun, Mar 25-Mar 26. - High winds across portions of the Aleutians, Sat, Mar 25. 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