518
FXAK02 KWNH 112353
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
652 PM EST Tue Feb 11 2025

Valid 12Z Sat Feb 15 2025 - 12Z Wed Feb 19 2025

...Overview...

Over the weekend, an upper low supporting a surface low will track
east through the northeast Pacific, for some modest precipitation
in the southern tier. Meanwhile an upper low will slowly meander
over the Bering Strait and gradually lift north into the Chukchi
Sea and high Arctic into next week. Upper ridging is forecast to
build over the Mainland northwestward from western Canada
combining with another ridge in the northern Pacific between
systems, while troughing undercutting the ridge should lead to
multiple surface lows/frontal systems moving across the Aleutians
and the surrounding Bering Sea and northern Pacific waters.


...Guidance Evaluation and Preferences...

Model guidance is in reasonably good agreement for the pattern
described above, especially early in the period. Smaller model
differences by early next week include the 12Z UKMET drifting east
of consensus with the northern upper low and took it over northern
Alaska, and the 12Z GFS being more aggressive with a shortwave
near the Alaska Peninsula Sunday that disrupts the mean ridge
starting to build there. By Monday-Tuesday, the main impactful
model differences are with energies and surface lows embedded
within the broad trough stretching east from an upper low south of
Kamchatka. Models vary with the timing, track, and strength of
each individual wave, but it is hard to pick out outliers in this
pattern.

Therefore the WPC forecast used a blend of the ECMWF/GFS/CMC/UKMET
(in decreasing order of usage) early in the period, and decreased
the proportion of deterministic models in favor of the GEFS and EC
ensemble means as the period progressed. Means comprised half the
blend by Day 7 and more by Day 8 given the model differences
particularly around the Aleutians.


...Weather/Hazards Highlights...

An upper low along with a surface low pressure system are forecast
to track through the northeast Pacific this weekend, while an
Arctic front should stall on the leading edge of high pressure
strengthening over northwest Canada. These features will support
modest precipitation for southern areas, including the Alaska
Peninsula to Southcentral and Southeast Alaska. A few snow showers
are possible farther north in areas of the Interior with a weak
front in place. Into early-mid next week, low pressure systems
tracking through the Aleutians are likely to produce rounds of
precipitation and perhaps some gusty winds there. Southerly flow
should allow for some precipitation eastward, leading to renewed
rain/snow chances in the Alaska Peninsula to Southcentral
Monday-Wednesday and perhaps into Southeast. At this point,
weather impacts look to generally remain below hazardous levels.

Cooler than average temperatures may linger across the North Slope
and western Mainland into Saturday as well as in Southeast Alaska,
but temperatures in most areas will gradually moderate closer to
normal and then above normal as next week progresses given the
increasing ridgy pattern. Lows should generally be more
anomalously mild than highs, with lows in the teens almost
reaching Fairbanks by mid-next week.


Tate


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

$$