Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
515 PM EST Fri Jan 22 2021
Valid 12Z Tue Jan 26 2021 - 12Z Sat Jan 30 2021
...Deep/Stormy lows to Threaten Alaska next week...
...Overview and Guidance/Uncertainty Assessment...
An active storm track with a series of potent closed lows/troughs
will reach the Aleutians and Bering Sea next week. Ample
downstream energy transfers over the AKPen/Southwest AK/Kodiac
Island and into the Gulf of Alaska offer more complex models
depictions of potentially deep systems, but guidance flow
evolutions and have trended in better agreement over the past few
days to bolster forecast confidence.
The WPC Alaskan medium range product suite were primarily derived
from a blend of reasonably well clustered guidance from the 12 UTC
GFS/ECMWF/UKMET/Canadian models days 4-5 (Tue-Wed) along with the
19 UTC National Blend of Models. Opted to replace the
UKMET/Canadian in the blend for days 6-8 with the more compatible
12 UTC GEFS/ECMWF ensemble means to maintain max WPC product
continuity next Thu-Sat.
...Weather/Hazards Highlights...
A well organized but exiting lead system digging though the
eastern Gulf of Alaska will bring some high winds/waves and
precipitation to the unsettled region and effect the Southeast
Panhandle Tue into Wed. Meanwhile, an upstream and very deep
system will spread heavy wrapping precipitation and a threat of
high winds/waves to the Bering Sea and Aleutians. This system
already has a well defined mid-latitude satellite signature off
eastern Asia and offers a substantial maritime threat with a
surface pressure risk to drop into the 950-960 mb range into the
Bering given favorable upper support. Details are less certain
with subsequent downstream transition across the AKPen/Southwest
AK/Kodiac Island, but guidance seems to rebound in support of a
pattern favoring another deepened northern to eastern Gulf of
Alaskan low by later next week to monitor.
Schichtel
Hazards:
- High winds across portions of the Aleutians, Tue-Wed, Jan 26-Jan
27.
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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