Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
528 PM EST Mon Feb 14 2022
Valid 12Z Fri Feb 18 2022 - 12Z Tue Feb 22 2022
...Stormy pattern continues for Alaska...
...Guidance/Predictability Assessment...
Models and ensembles offer reasonably similar larger scale flow
evolution through medium range time scales. However, there remain
issues with the timing and focus of embedded systems as
day4/Friday. A composite of the "best" clustered 12 UTC GFS/ECMWF
and GEFS/ECMWF ensemble means seems to present a reasonable
forecast days 4-6 (Friday-Sunday) with respect to WPC product
continuity. Prefer just the ensemble means days 7/8 (next
Monday/Tuesday) amid normal forecast spread growth.
...Pattern and Weather/Hazard Highlights...
It remains generally the case that more in a series of highly
unsettling storms seem on tap over the next week, both with
several deep lows near the western Aleutians and as ample energies
from multiple systems again break downstream across Southwest
Alaska, the AKpen/Kodiak Island, south-central Alaska, the Gulf of
Alaska and Southeast Alaska. System timing variance is not ideally
set through medium range time frames, but has marginally improved
within an overall stormy pattern that offers above normal larger
scale predictability. While the short range also remains very
active, expect an additional series of deep and relatively slow
moving storms for the western Aleutians through medium range time
scales into the weekend and early next week. Each with presenting
a maritime and Aleutians threat with potential for high
winds/waves and wrapping rains. System energies progressing
downstream should spread a focus for deepened moisture fueling
heavy precipitation from a warmed Southwest AK and the
AKpen/Kodiak Island through southern/southeast Alaska. While
active in the short range, expect additional focus especially this
Friday and the weekend, then again early next week. This includes
threats of multi-day heavy coastal rains and inland/terrain
enhancing snows.
Meanwhile, expect overall Arctic stream upper troughing from the
North Slope down into the northern Interior, but generally modest
moisture and snow potential outside of favored terrain in lower
atmospheric flow dominated by cooled surface high pressure.
Temperatures are expected to be well above normal over a warmed
southern Interior, but cold enough for periods with enhanced snows
considering ample support with approach and passage of a series of
moistened southern stream systems slamming inland through a mean
upper ridge position combined with a lingering and wavy surface
frontal system focus. The best bet for organized snows may be
Friday, then possibly again early next week.
Schichtel
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle,
Thu-Fri, Feb 17-Feb 18.
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