Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
546 PM EST Tue Jan 24 2023
Valid 12Z Sat Jan 28 2023 - 12Z Wed Feb 01 2023
...Significant pattern change will lead to increased chances of
precipitation, milder than normal temperatures, and potential for
gusty winds from the Aleutians to the western mainland late this
week to early next week...
...Overview...
A pattern change will be underway heading into the weekend as mean
upper ridging builds in atop the state, lasting into next week in
response to a couple of large upper troughs/lows in the western
Bering Sea. Above average temperatures will abound over especially
the western mainland given the ridge. The Aleutians and Alaska
Peninsula and into the western mainland are likely to see more
active weather with precipitation and gusty winds. Meanwhile the
Panhandle should see a drying trend as well as cooling
temperatures and some outflow winds with northerly flow to the
east of the ridge axis.
...Model Guidance/Predictability Assessment...
The 12 UTC GFS/UKMET and latest GEFS/ECMWF ensemble mean solutions
seem best clustered in amplified flow with good overall
predictability despite lingering smaller scale embedded system
timing/strength differences. A blend, weighted increasingly to the
compatible ensembles and most amplified GFS for next week tends to
mitigate these differences consistent with uncertainty and
maintains mainland upper ridge strength reasonably on the stronger
side of the full envelope of solutions as collaborated with
Alaskan offices. The main uncertainties in the pattern are
associated with the interaction of shortwaves around/into the
ridge as system/impulse integrity will channel the main weather
focus.
...Sensible Weather and Potential Hazards...
It generally remains the case that upper ridging becoming
established into the mainland should help moderate temperatures to
well above normal across much of the state, with possible +30F
anomalies for parts of the northwestern mainland by early next
week. Temperatures could warm above the freezing mark in the
southwestern mainland/Bristol Bay area, quite a change from
current conditions. There could be impacts from snowmelt with
these above freezing temperatures, and especially if precipitation
falls as rain or freezing rain there due to the relative warmth.
This is a possibility late week as precipitation crosses the
Aleutians/Alaska Peninsula as well as some possibly gusty winds
along a front stemming from the western Bering low, which
potentially makes its way into the western mainland, though the
impacts farther east are less certain. The pattern seems to
generally repeat early next week for another round of possible
western Alaska precipitation/winds. Some available moisture could
lead to snow showers over much of the mainland through next
weekend, but currently only light QPF is expected. The Panhandle
on the other hand is likely to see drier conditions than they have
lately, as well as temperatures becoming slightly below average,
and winds perhaps becoming gusty with offshore flow.
Schichtel
Hazards:
- Much above normal temperatures across portions of mainland
Alaska, Fri-Sun, Jan 27-Jan 29.
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
Hazards:
- Heavy precipitation across portions of mainland Alaska and the
Aleutians, Thu-Fri, Jan 26-Jan 27.
- Much above normal temperatures across portions of mainland
Alaska, Fri-Sun, Jan 27-Jan 29.
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