Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
722 PM EDT Mon Mar 20 2023

Valid 12Z Fri Mar 24 2023 - 12Z Tue Mar 28 2023

...Overview/Guidance Evaluation/Predictability Assessment...
A broad upper trough will be situated over northwestern Alaska for
the end of the week, and shortwave energy pivoting around the
southern periphery of this trough will support a relatively weak
surface low over the eastern Gulf that should be drifting
southeast through Saturday.  Another well organized low pressure
system is forecast to make weather headlines going into the
weekend as it approaches the western Bering and eastern Siberia as
an upper level trough becomes amplified over this region, and a
downstream upper ridge will likely be in place across eastern
mainland Alaska and western Canada for Sunday into Monday.

The model guidance initially has a good overall depiction of the
synoptic scale pattern, so a multi-deterministic model blend
sufficed as a starting point in the forecast process for the end
of the week and into early Saturday.  The CMC is a bit farther
west with the track of the Bering low across eastern Siberia
compared to the model consensus later on Saturday and into Sunday.
 The GFS becomes stronger with a trailing low across the Aleutians
by Sunday and stronger with the downstream ridge axis across the
Gulf and eastern Alaska.  More of the ensemble means were
incorporated into the forecast for the Sunday to Tuesday time
period to account for increasing model differences.

...Weather/Hazard Highlights...
Some coastal rain and mountain snow will likely be ongoing from
the northern Gulf low late in the week, although the heaviest
precipitation is likely to be over by that time.  However, the
main weather story is expected to be the increase in snow and wind
associated with the approach of the next Bering Sea low pressure
system over the weekend.  Heavy snow is likely for western
portions of the Brooks Range where 1 to 2 feet of snowfall
accumulation is possible from Saturday night to early Monday. 
Heavy snow is also increasingly likely for southern portions of
the Seward Peninsula where greater than a foot of heavy wet snow
is possible as well.  High wind gusts on the order of 40 to 60 mph
will be possible across coastal portions of western Alaska as a
strong pressure gradient develops, and some coastal flooding may
also be a problem.  In terms of temperatures, expect readings to
generally be running 10 to 25 degrees above late March averages
for central and northern portions of the state for the weekend as
deep southerly flow ahead of the Bering Sea low advects a much
warmer maritime air mass across the Interior, with the potential
for many inland areas reaching highs above freezing on Sunday,
even including areas north of the Brooks Range.  A return to more
seasonal March conditions is likely by early next week as a cold
front crosses most of the state.

Hamrick

Hazards:
- High winds across portions of western mainland Alaska and the
Aleutians, Sat, Mar 25.
- Heavy snow across portions of western mainland Alaska, Sat-Sun,
Mar 25-Mar 26.


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