Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
539 PM EST Sat Jan 11 2025

Valid 12Z Wed Jan 15 2025 - 12Z Sun Jan 19 2025

...General Overview...

Active weather will continue through mid-next week for portions of
the southern Mainland and Southeast Alaska as a couple weak lows
push onshore. Elsewhere, high pressure will dominate the weather
pattern through the work week, resulting in low precipitation
chances and cooling temperatures to near normal for the interior
and northern Alaska. The next impactful weather systems will skirt
just south of the Aleutians and gradually lift into the Bering Sea
late next week into the weekend, bringing chances for heavy
precipitation and gusty winds to the Aleutians, Alaska Peninsula,
and southwestern Alaska.


...Model Guidance Assessment...

The 12Z suite of model guidance remains in good agreement on the
upper level pattern and surface features through mid-next week.
Model spread increases significantly after Friday as the models
try to resolve the strong systems moving from the Pacific to the
Bering Sea and how they interact with each other. The ECMWF shows
the best run-to-run consistency while the 12Z GFS came in with a
more southern trend than what the consensus has been suggesting.
The CMC has fallen more in line with the general consensus today,
but still struggles to resolve the low interactions after Friday.

For WPC's forecast, a blend of the deterministic GFS/ECMWF/CMC was
used for Wednesday and Thursday, with higher weight placed on the
ECMWF and GFS. For Friday onward, ensemble means from the
GEFS/ECENS/CMCE were added in increasing amounts while the CMC was
phased out. Higher weight was placed on the ECMWF/ECENS next
weekend due to the greater level of run-to-run-consistency
compared to the other model guidance. This blend resulted in a
good starting point for the forecast that was close to the
ensemble mean solutions.


...Weather/Hazards Highlights...

Heavy precipitation will linger in Southcentral and Southeast
Alaska through mid-week as two relatively weak low pressure
systems track through these regions. Above normal temperatures
will make rain the main precipitation type, but wintry mixed
precipitation and snow will be possible in the higher elevations.
Precipitation chances will gradually decrease across Southeast
Alaska later next week as high pressure builds across the Gulf.
Precipitation chances will also be low for the interior and
northern Alaska under the influence of Arctic high pressure.

Precipitation chances will focus on western portions of the state
late next week as the next low pressure system tracks along the
Aleutians. This system will likely weaken and lose momentum as it
heads into high pressure ridging stretching from the Gulf to the
Arctic, causing it to become nearly stationary just south of
southwestern Alaska. Another strong low pressure system will
follow quickly behind the first, tracking into the Bering Sea and
pushing a frontal boundary across the Aleutians this weekend.
These systems will push an anomalously warm air mass into
southwestern Alaska and will result in a prolonged period of heavy
precipitation for the eastern Aleutians, Alaska Peninsula,
Southcentral and southwestern Alaska. Rain falling on top of snow
could enhance snowmelt and lead to localized flooding concerns in
some areas, such as Kodiak Island . The strong nature of the low
will also likely produce strong gusty winds from the Aleutians to
southwestern Alaska late next week into the weekend.


Dolan


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