Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 609 PM EDT Mon Apr 4 2022 Valid 12Z Fri Apr 8 2022 - 12Z Tue Apr 12 2022 ...Overview... A deep upper level trough and closed low is expected to be in place across northwestern Alaska and the eastern Bering on Friday, and a weakening surface low will affect southern coastal portions of the state. By the weekend, the polar low continues to govern the weather pattern across the North Slope and Arctic Coast, while an upper ridge axis likely builds in across the Aleutians and the southwestern mainland. There is also a model signal for a low pressure system approaching the Aleutians by the beginning of next week. ...Guidance/Predictability Assessment... The 12Z model guidance suite continues to show fairly good synoptic scale agreement with the overall pattern through the end of the week, and a general deterministic blend represents a good forecast starting point through early Saturday. By late Saturday and into Sunday, models struggle with shortwave energy crossing the northern periphery of the Aleutians upper ridge, and there is also a good deal of longitudinal spread in the main polar low by Sunday. The feature with the greatest model agreement is the upper ridge in place across southwest Alaska through early next week. Due to these uncertainties in the Sunday through Tuesday time period, the WPC forecast leaned increasingly more towards the ensemble means to help mitigate these differences, along with some previous WPC continuity. ...Weather/Hazard Highlights... Onshore flow from the dissipating low pressure system over the Gulf of Alaska will likely continue to generate areas of moderate rain and mountain snow from the Kenai Peninsula to the southeast panhandle region on Friday, before abating on Saturday as a drier overall pattern commences. Patchy areas of light snow are likely across central and southern portions of the Interior going into the weekend, and mainly dry conditions farther north. Depending on the eventual evolution and track of the next low reaching the Aleutians by next Sunday/Monday, widespread showers and some gusty winds can be expected for these islands, with potentially enhanced rainfall for windward portions of the eastern Aleutians. Most of central and eastern Alaska will likely have readings near or slightly above normal for the end of this week, and below average for the western mainland. A brief cooling trend appears likely across much of the mainland going into Saturday, followed by a return to milder conditions by Sunday and into early next week as the upper level ridge builds in overhead. 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