Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
609 PM EST Mon Jan 30 2023
Valid 12Z Fri Feb 03 2023 - 12Z Tue Feb 07 2023
...Pattern overview and Weather/Hazard Highlights...
An reasonably active and overall progressive flow pattern expected
to develop over much of Alaska and vicinity from later this week
into early next week should feature a general storm track from the
northeast Asia through the northwest Pacific to the Bering Sea, a
blocky closed Arctic Ocean upper ridge/high overtop, general
northern mainland upper troughing and the undercutting of Pacific
system energies into the Gulf of Alaska/northeast Pacific.
Lead deepened low transition over the southeast Gulf of Alaska
should provide a late week focus for moderate to heavy
precipitation over the southern Panhandle including terrain
enhanced mountain snowfall. Subsequent deep energy formation and
track of an upstream deepened low in this period and through the
weekend is expected to be diverted farther offshore to the south,
with less Alaskan effect beyond maritime interests.
Upstream, a modest Northwest Pacific low is uncertainly slated to
work into the southeast Bering Sea Thursday into Friday along with
some sensible weather focus into the Aleutians and
Southwest/Western Alaska, but most likely mostly offshore. A much
deeper and well organized storm has a stronger guidance signal and
should work steadily across the Aleutiand and southern Bering Sea
Friday and the weekend. The large and windy circulation should
wrap some periods of moderately enhanced precipitation to
Southwest/Western Alaska and downstream with triple point low
enhancement into the Alaskan Peninsula, Kodiak Island and
increasingly into the eastern Kenai Peninsula/south-central Alaska
and eventually the Southeast Panhandle early next week.
...Model Guidance/Predictability Assessment...
The 12 UTC GFS/ECMWF/UKMET/Canadian and GEFS/ECMWF/Canadian
ensemble means offer quite similar larger scale flow evolutions
across Alaska and vicinity through medium range time scales in a
pattern with seemingly above normal predictability. Even so,
embedded system differences evident throughout the period seem
best mitigated by usage of a composite blend to maintain good
product continuity. An exception may be with an unusuallly diverse
Day 4/Friday low position to the Bering Sea where the 12 UTC GEFS
mean may offer the best centroid cluster position from the full
envelope of guidance lows. Manual adjustments were also applied at
WPC to ensure sufficient system and wind intensity.
Schichtel
Hazards:
- Heavy precipitation across the eastern Kenai Peninsula, Sun, Feb
5.
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