Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
746 PM EDT Tue May 6 2025

Valid 12Z Sat 10 May 2025 - 12Z Wed 14 May 2025


...General Overview...

Much of mainland Alaska will likely be situated between two 
upper-level gyres through the medium-range period. The most active
weather will be associated with the gyre centered generally over
the Bering Sea, as frequent arrival of moderately strong cyclones
will keep weather unsettled for the Aleutians and along the 
southern coastline of mainland Alaska into the middle of next 
week. It appears that the unsettled weather will most likely reach
southwestern Alaska by late this weekend with the arrival of the 
second cyclone.


...Guidance/Predictability Assessment...

Models and ensemble means indicate that there will be three
moderately strong cyclones to track northeastward from the 
Pacific across the Aleutians, then weaken and be absorbed into 
the upper-level gyre centered over the Bering Sea through the 
medium-range period. All guidance show good agreement on the 
first cyclone reaching the Bering Sea by this weekend, but with 
the latest ECMWF and 00Z EC mean showing more pronounced triple- 
point low development to the south of the Alaska Peninsula. The 
second cyclone taking a similar track to cross the Aleutians into 
the Bering Sea late this weekend into Monday shows more model 
uncertainties, with the GFS taking it on a much faster and more 
northeastward track into southwestern Alaska. The 12Z ECMWF is the
slowest guidance of all, with the cyclone center not reaching the
central Aleutians until Monday. The latest GFS runs have 
progressively backed off on the fast forward motion for this 
cyclone, although the latest EC-AIFS has just switched to a
comparable fast solution. The WPC blend leans slightly toward the 
slower side of the guidance, coming up with a solution comparable 
to the CMC. For the third cyclone, the ensemble means from global 
models show good agreement on bringing this cyclone to the 
Aleutians by Tue-Wed of next week via a similar track.

The WPC medium-range forecasts for Alaska begin with an even blend
of the 12Z EC/00Z EC mean and 12Z GFS/GEFS together with 20% from
the CMC/CMC mean, followed by slightly higher percentages from the
EC clusters. The blend then transitions to mostly from the ensemble
means toward the end of the forecast period.


...Weather/Hazards Highlights...

Rain and high-elevation snow are likely to be ongoing along the 
southern coastline into the Panhandle region into Saturday before 
starting to gradually taper off on Sunday as the Gulf low 
continues to weaken. Meanwhile, unsettled weather is forecast to
continue through the Aleutians while getting more frequent and
widespread by Sunday with the arrival of a moderately strong
cyclone from the Pacific. This system should spread rainy weather
and high-elevation snow progressively farther into southwestern 
Alaska and along the southern coastline early to middle of next 
week with amounts not expected to be excessive. A third cyclone 
taking a similar track like its predecessors should bring 
additional unsettled weather to the Aleutians into midweek.

Temperatures are expected to be above average across southwestern
and interior mainland Alaska while the North Slope will be below 
normal. The Arctic Coast has the coldest anomalies, but these too
should moderate going forward. The ridge of high pressure from 
northern Alaska into the Arctic Ocean is forecast to weaken 
through time with a gradual warm up expected by midweek next week
for the North Slope.

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