Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
707 PM EDT Sat Oct 15 2022
Valid 12Z Wed Oct 19 2022 - 12Z Sun Oct 23 2022
...Major storms offer a heavy precipitation and high wind/wave
maritime threat with impact from the Aleutians through
South-central/Southeast Alaska next week...
...Overview and Guidance/Predictability Assessment and
Weather/Hazards Highlights...
The 12 UTC GFS/ECMWF/UKMET/Canadian model solutions seem well
clustered Wednesday into Friday and are well supported by
ensembles, bolstering forecast confidence. In this period, low
energies into this period will keep the eastern Bering Sea and
Western/Southwestern Alaska into the Interior unsettled with some
periods of wintry precipitation and some gusty winds. This
includes influence from Arctic stream upper trough/low energies
lingering over Northwest Alaska.
A big story to highlight remains the track a major/deep low with
central pressure dropping near 950mb and gale to hurricane force
winds into the Gulf of Alaska Tuesday into Wednesday in what is
proving to be quite an astounding series of storms so far in
October in a highly energetic pattern. Forecast spread/uncertainty
has significantly decreased with this potent storm, albeit still
with an uncertain connection to Twentyone and Joint Typhoon
Warning Center (JTWC) invest area 91W over the west Pacific. The
composite depiction of a dangerous system track offers a
significant renewed threat of stormy seas/winds, heavy rain/runoff
issues and elevation snowfall threats into South-central and
Southeast Alaska Tuesday into Wednesday given long fetch moisture
connection and potent upper low/trough support.
Meanwhile, there is an emerging guidance signal for a large
deepened low to flourish and bring widespread high winds/waves
across the Bering Sea through the Aleutians into the north Pacific
along with wrapping heavy rains in a broader mean circulation
Tuesday into next Saturday. The details and embedded low
interactions and reformations within the flow remains less
certain, lending preference from a composite blend of the 12 UTC
GEFS/ECMWF ensemble means to mitigate the less predictable
forecast conponents. This overall gyre also threatens much of
West/Southwest Alaska into the Interior and underneath through a
stormy AKpen/Kodiak Island into the Gulf of Alaska and inland with
wrapping/frontal inflow into South-central then Southeast Alaska
Wednesday into next weekend with downstream potent energy
transition and system progression.
Schichtel
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