Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
628 PM EDT Mon Mar 21 2022
Valid 12Z Fri Mar 25 2022 - 12Z Tue Mar 29 2022
...Pattern Overview and Weather/Hazard Highlights...
It remains that case that a closed high/ridge is expected settle
over the Arctic Ocean through later week/weekend before possible
ejection and replacement by a westward working upper trough. A
generally benign weather pattern for the North Slope and Alaskan
Interior could become more unsettled over the North Slope with
this flow transition. Meanwhile, a closed low/trough centered over
the Alaskan Peninsula to northwest Gulf of Alaska into Friday then
reforms and settles over the south-central Gulf of Alaska and down
into the northeast Pacific. Lingering flow around
associated/deepened low pressure systems may nonetheless present a
lingering pattern favorable for some periods of moderate
precipitation (coastal rains/terrain snows) from south-central
Alaska to the Southeast Alaskan Panhandle.
The WPC Hazards Outlook desk in collaboration with the Alaska
Region ROC identified a threat for heavy precipitation into Kodiak
Island/South-Central Coastal Alaska Thursday into early Friday
with approach of a lead/organized northern Gulf of Alaska low.
Trends from latest guidance are slightly more offshore now with
this low. Later, there is a growing guidance signal that deep low
genesis with amplified upper trough energies progressing off
eastern Asia will track toward the Aleutians later this week and
spread enhanced winds, rains and waves across the region before
progressing into the Gulf of Alaska into early next week. Yet
another deepened low may work over the north Pacific in the wake
of this system, but with increased uncertainty at this longer time
frame.
...Guidance/Predictability Assessment...
The best clustering of model/ensemble guidance and WPC Alaskan
medium range product continuity seems to include the 12 UTC
ECMWF/Canadian and GEFS/NAEFS/ECMWF ensemble means days 4-7
(Friday into next Monday), albeit in a pattern with average to
below normal system predictability, mainly with maritime lows.
Only the less detailed ensemble means remain well clustered later
next Monday into next Tuesday, but do seem to provide reasonably
consistent pattern evolution.
Schichtel
Hazards:
- Heavy precipitation across portions of mainland Alaska, Thu, Mar
24.
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