Alaska Extended Forecast Discussion National Weather Service College Park MD 712 PM EDT Wed Jun 11 2025 Valid 12Z Sun 15 Jun 2025 - 12Z Thu 19 Jun 2025 ...Guidance Evaluation/Preferences... The medium-range forecast period for the Alaskan domain through next Thursday will likely feature a 500-mb ridge gradually closing off into a separate anticyclone over northern Alaska while multiple vortices over the Bering Sea and northern Pacific will slide toward and merge into the Gulf of Alaska cyclone under a confluent upper-air pattern in that vicinity. The 12Z ECMWF today shows more aggressive downstream cyclogenesis on Day 5 Monday off the west coast of Canada, and subsequent closer approach of the cyclone toward the Alaska Panhandle on Day 6 Tuesday. This is in contrast to the much slower progression of the cyclone in yesterday's 12Z EC run. The EC means also show a more progressive tendency in this regard compared with the GFS, GEFS, and the Canadian model. Even though deterministic global model solutions show increasing divergence on the timing and degree of interaction of various vortices, the overall agreement on the aforementioned evolution of the synoptic scale pattern among ensemble means remain very good through Day 8. 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 moderate rainfall associated with a pair of occluded cyclones early this weekend will mostly focus on the south-facing shore of the southern Alaska Peninsula for the remainder of the weekend and perhaps into early next week. Meanwhile, precipitation across portions of the Panhandle should have tapered off by this weekend 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 rain tapering off on Sunday when the Aleutian system slides toward the Gulf of Alaska. 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 and further up into portions of the western mainland can also expect an increasing chance of scattered showers and thunderstorms from early to midweek next week associated with instability on the northern edge of the Gulf of Alaska circulation. Meanwhile, rain chances are expected to gradually increase from west to east for the Aleutians through midweek next week as ensemble means indicate a good chance for the next Pacific cyclone to approach the region. Under the gradually amplifying ridge forecast for northern Alaska, afternoon temperatures are expected to soar well into the 80s to near 90 degrees for the eastern interior especially across the Yukon Flats this coming Sunday. This will be followed by a slow moderation of the heat heading 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