Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
530 PM EST Tue Feb 22 2022
Valid 12Z Sat Feb 26 2022 - 12Z Wed Mar 2 2022
...Overview...
The upper ridge axis that will be in place across the state for
the end of this week should be shunted east to western Canada by
the weekend as a broad upper trough becomes established over the
Gulf, with a couple of surface lows tracking towards the southeast
Panhandle and British Columbia coast. A brief ridge axis builds
northward over the Aleutians by early next week ahead of the next
amplified trough approaching from the west. This will equate to
above average temperatures across most of the mainland and periods
of rain/snow for coastal areas.
...Guidance/Predictability Assessment...
The 12Z deterministic guidance and the ensembles have the best
overall depiction regarding the retreating ridge axis over eastern
Alaska/western Canada at the beginning of the forecast period
Saturday, and some latitudinal differences with the low pressure
system over the Gulf region and also across the Bering. Basically
all of the deterministic guidance and the 12Z GEFS/ECENS mean are
now farther east with both of these lows compared to the 00Z
ECENS. By Monday, models continue to struggle with the next low
over the southern Gulf, with the UKMET northwest of the model
consensus and the ECMWF stronger but close to the consensus
regarding placement. However, the guidance at this time has a
good handling of the ridge briefly building over the Aleutians.
With the next storm system approaching the Aleutians by next
Tuesday, it appears the GFS is stronger than the CMC/ECMWF, and a
second strong storm likely follows that system by the middle of
next week.
Taking these factors into account, the WPC fronts/pressures
forecast is primarily derived from a multi-deterministic blend for
this weekend, and then greater weighting on the ECMWF and GEFS
mean, along with some CMC, GFS, and previous WPC continuity going
forward into early next week.
...Weather/Hazard Highlights...
Strong low-level flow to the east of a wave (and trailing front)
tracking from south of the Alaska Peninsula into the northern
Bering Sea Friday into early Saturday will enhance the potential
for heavy precipitation along the southern coast of the mainland
late this week. The Kenai Peninsula should see the highest totals
from this event. The heavy precipitation may extend as far east
as the Panhandle, with low-confidence details for a possible
trailing wave determining amounts and duration of activity over
the southeastern coast/Panhandle over the weekend. Some
precipitation could extend farther north over the mainland but in
much lighter and scattered form. While precipitation along the
southern coast and Panhandle should generally trend lighter with
time, another area of moisture could reach the southeastern
coast/Panhandle early next week if a northeastern Pacific system
tracks close enough. A strengthening northwestern Pacific to
western Aleutians/Bering Sea system and leading front may bring
increasing winds and rounds of rain across the Aleutians for early
next week.
Coverage of much above normal temperatures will be greatest this
upcoming weekend. Highest anomalies should be over the
northwestern half of the mainland and some areas could see
readings up to 35 degrees above normal, especially for lows.
Above freezing temperatures will likely reach as far north as the
Brooks Range. Temperatures should steadily moderate from south to
north early next week but remain above normal over most areas for
the majority of the forecast period.
Hamrick
Hazards:
- Heavy precipitation across portions of southern coastal Alaska,
Friday, Feb 25.
- High winds across portions of southern mainland Alaska, Friday,
Feb 25.
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