Alaska Extended Forecast Discussion National Weather Service College Park MD 729 PM EDT Tue Jun 10 2025 Valid 12Z Sat 14 Jun 2025 - 12Z Wed 18 Jun 2025 ...Guidance Evaluation/Preferences... The medium-range forecast period through next Wednesday for the Alaskan domain will likely feature a 500-mb ridge gradually closing off into a separate anticyclone over northern Alaska while multiple vortices from the Bering Sea and northern Pacific will slide toward and be absorbed into the Gulf of Alaska cyclone under a confluent upper-air pattern. Even though deterministic global model solutions show increasing divergence in resolving the timing of the various vortices, the agreement among ensemble means remain very well through Day 8 with respect to the aforementioned evolution of the synoptic scale pattern. The WPC Alaskan medium forecast package was mainly derived from a composite blend of moderately well-clustered guidance comprising of 40% from the 12Z ECMWF and 00Z/12Z EC mean, 40% from the 12Z GFS and 12Z GEFS, and 20% from the 12Z Canadian and its ensemble mean. The composite blend transitions to mainly a blend of the ensemble means by Day 7 & 8. ...Weather/Hazards Highlights... No hazardous weather is forecast for the Alaskan domain through the medium-range forecast period. The main concern in terms of rainfall under this synoptic pattern will be across the southern Alaska Peninsula Friday into Saturday when moderate to locally heavy rainfall is expected ahead of a pair of occluded cyclones with gale-force winds. Lingering precipitation early this weekend across portions of the Panhandle is expected to taper off later on Saturday as an old occluded low retrogrades and moves further offshore, eventually be absorbed by the system sliding through the eastern Aleutians. The southwestern coastal sections will also see a good chance of rain from this system this weekend. By early next week going into midweek, chance of rain will be on the increase for the southern coastline into the Panhandle as the Aleutian system merges with the Gulf of Alaska low. The southern interior sections can also expect an increasing chance of scattered showers and thunderstorms from early to midweek next week along the northern edge of the Gulf of Alaska circulation. Under the gradually amplifying ridge forecast for northern Alaska, afternoon temperatures are expected to soar well into the 80s for the eastern interior especially across the Yukon Flats by this weekend. This is followed by a slow moderation forecast by the NBM. The strength of the upper ridge will be watched in subsequent forecasts for any signs of 90-degree heat going into early next week. Kong 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