Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
708 PM EDT Wed Apr 13 2022
Valid 12Z Sun Apr 17 2022 - 12Z Thu Apr 21 2022
...Deep cyclone transitions from western Pacific Typhoon Malakas
forecast to affect the Aleutians Sunday-Tuesday...
...Pattern and Weather/Hazard Highlights...
A deep cyclone originates from Typhoon Malakas currently located
in the western Pacific is forecast to approach the Aleutians for
the beginning of next week. Wrapping rains driven by high winds
associated with the significant storm will also offer a widespread
maritime threat.
Otherwise, an upper level ridge axis should remain in place across
much of mainland Alaska, with a surface high settling north of the
Arctic Coast. However, a weak undercutting upper low will likely
track westward across the Interior this weekend and then meander
over the Bering Sea. Meanwhile, a strong low pressure system over
the Bering Sea should weaken by the weekend. In this pattern, much
of the state should begin the period with temperatures generally
near to above average, and then colder weather arrives in time for
the weekend for eastern areas of the state as cold air moves in
from western Canada. Milder conditions should continue into early
next week for northern Alaska near a closed upper high and over
the southwestern mainland with deep Aleutian system affect. In
terms of precipitation, most of the Interior region should remain
dry and any periods of rain and mountain snow will likely be
modest for southern and southeast Alaska as storm systems spin
well offshore.
...Guidance/Predictability Assessment...
Pretty much the only system of concern continues to be the
extratropical counterpart of Typhoon Malakas forecast to move
near/through the Aleutians early next week. Model QPF and cyclone
depth had backed off in earlier runs today (especially the GFS).
However, the 12Z ECMWF and CMC went with a stronger cyclone and
more northerly track in a similar fashion as yesterday's GFS. A
composite blend of 40% from the 06Z GFS/12Z GFS/12Z GEFS, 40% from
the 12Z ECMWF/12Z EC mean and 20% from the 12Z Canadian/CMC mean
yielded solutions that are quite compatible with WPC continuity.
It should offer some system details to the impending cyclone and
also to most other features evident over the rest of Alaska in a
pattern with near average predictability. By Days 6-8, the blend
transitions to mostly a consensus of the ensemble means, which
should provide a decent starting point for the longer range
forecasts.
Kong/Schichtel
Hazards:
- Heavy precipitation across portions of mainland Alaska and the
Aleutians, Tue, Apr 19.
- Heavy precipitation across portions of the Aleutians, Sun-Mon,
Apr 17-Apr 18.
- High winds across portions of mainland Alaska and the Aleutians,
Tue, Apr 19.
- High winds across portions of the Aleutians, Sun-Mon, Apr 17-Apr
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