118
FXAK02 KWNH 272357
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
657 PM EST Thu Feb 27 2025

Valid 12Z Mon Mar 03 2025 - 12Z Fri Mar 07 2025

...Aleutians/North Pacific systems may bring enhanced
precipitation and gusty winds into southern coastal areas of
Mainland Alaska next week...

...Overview...

Guidance generally agrees that an upper ridge from the Panhandle
and western Canada into Mainland Alaska early next week should
drift slowly eastward as an upper low tracks along the Aleutians
and Alaska Peninsula.  The combination of a leading system
tracking northward toward/across the Alaska Peninsula and then one
or more surface lows emerging from the Aleutians/mid-latitude
Pacific should promote areas of focused rain and snow along the
southern coast, extending into the Panhandle later in the week.
Mid-late week details remain somewhat uncertain in light of
guidance spread for the shape of upper flow and specifics of
surface lows.  These systems may produce areas of strong winds as
well, though generally staying below hazardous criteria.  The
forecast pattern will favor widespread above normal temperatures
aside from more moderate readings over the far western mainland
early-mid week.


...Guidance Evaluation and Preferences...

A general guidance blend consisting of the 12Z ECMWF/GFS/CMC/UKMET
in order from more to less weight represented prevailing themes
well for significant features.  With typical detail variability,
solutions have been fairly stable over the past couple days or so
with a wavy front over the western mainland as of early Monday and
connecting with another front extending eastward.  The boundary
over the northwestern mainland should dissipate quickly, yielding
a southwest-northeast oriented front by Tuesday and beyond.
Continuity is also fairly good with a general area of low pressure
south of the Alaska Peninsula tracking northward into the area by
around midweek before losing definition.  Latest machine learning
(ML) models offer reasonable support for the track/depth in the
operational models.  Meanwhile strong northwestern Pacific low
pressure should track close to the western Aleutians by Tuesday.

By Wednesday most of the ML models suggest an eastward shift in
upper dynamics and surface low pressure emphasis into the eastern
Aleutians/southwestern Alaska Peninsula, while reflecting some of
the dynamical model theme of the initial parent low lingering
somewhat south of the Aleutians.  Then the overall area of low
pressure should wobble eastward later in the week, while details
diverge for individual waves.  During Wednesday-Thursday an
average among the 12Z GFS/CMC and the 00Z ECens/12Z CMCens means
provided the best reflection of ML model ideas while also
reflecting an evolution not too far from yesterday`s continuity.
For now there is not much support for the past couple ECMWF runs
that have been depicting a farther south track for the eastern
wave.  That said, there are hints in other guidance for a less
defined frontal wave near the ECMWF`s track.  Thus a minimal
amount of ECMWF input could be maintained in this time frame
before the model returned to agreement with the ensemble means
(though with the GEFS on the weak side) by next Friday.  On the
other hand, the 12Z GFS became a weak/suppressed extreme next
Friday to favor removal of its input at that time.  From the
big-picture perspective there is a continuing question of the mean
upper low`s shape in the mid-late week time frame.  Most ML models
and the AIFS mean suggests more east-west elongation of the upper
low (resembling the 12Z CMCens mean around Thursday), which would
somewhat temper the amount of moisture reaching the southern coast
relative to the more rounded shape in a majority of dynamical
solutions.  At the very least there is a good overall cluster to
support somewhat more precipitation than depicted in the 12Z ECMWF
late in the week.

The gradient ahead of another western Pacific storm may reach into
the western Aleutians by next Friday.  Some GFS runs (06Z in
particular and to some extent the new 18Z version) have strayed on
the fast side.  A number of ML models offer the potential for
timing to be even slower than the dynamical model/ensemble
majority so it will be worth watching for such trends in future
runs.


...Weather/Hazards Highlights...

Low pressure to the south of the Alaska Peninsula early in the
week should lift northward into the region, with flow to its east
primarily focusing precipitation between the far eastern Alaska
Peninsula and the Kenai Peninsula, with lesser totals extending to
the Southcentral coast.  Some rain/snow may be locally moderate to
heavy but at this time is not likely to reach hazardous criteria
on an organized scale.  Meanwhile, periods of light snow will
extend northward across the western mainland near a wavy front
through midweek as a portion of the front weakens to a stationary
inverted trough.

The system forecast to track from the northwestern Pacific into
the Aleutians during the first half of the week should become the
dominant feature by mid-late week.  At that time the overall
system may consist of more than one low, with specific
track/strength details not yet well resolved.  The surface low(s)
will likely increase winds across a broad area over the Pacific
and Bering Sea plus spread organized precipitation across the
Aleutians and then farther eastward along the Alaska
Peninsula/southern coast.  The Panhandle should see increasing
precipitation as well after midweek.  Guidance differences for the
overall shape of upper flow and individual surface low tracks
temper confidence in the precise magnitude of mid-late week
precipitation along the southern coast, so the Days 3-7 Hazards
Outlook currently does not depict any heavy precipitation areas.
Continue to monitor forecasts as some individual solutions would
lead to more pronounced focus.

Expect temperatures to be above normal over a majority of the
state through the period with a slight warming trend over some
areas continuing into early next week.  There should be decent
coverage of plus 10-20F or greater anomalies.  The main exception
will be over far western areas.  The wavy front pushing across the
western mainland early next week may bring temperatures somewhat
closer to normal for a time and then another cooling trend may try
to move in from the west by next Friday.

Rausch


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

$$