Gale Warning 207, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
531 AM AKDT Wed Mar 22 2023

.ANALYSIS AND UPPER LEVELS...

The pattern remains amplified as strong low pressure is currently
moving northeastward across the Gulf of Alaska. A second low is
currently moving northeastward across the northern Bering Sea.

Closer to the surface, radar and observations show snow moving
across the northern Gulf into the Southern Kenai Peninsula, Prince
William Sound and then wrapping around the northern Alaska
Peninsula. A few flurries were reported in the Anchorage Bowl,
though the strong downslope forcing is keeping us mainly dry.

&&

.MODEL DISCUSSION...

Models are in good synoptic agreement. The biggest forecast
challenge continues to be resolving small scale local effects.

&&

.AVIATION...
PANC...VFR conditions will persist for this TAF package. A
southeasterly Turnagain Arm wind may periodically bend into
Anchorage after 22/15z. Low level wind shear is expected from
22/15z through 23/03z as southeasterly winds will be significantly
stronger aloft than at the surface.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Today through Friday)...

A strong low pressure will move across the southern tip of Kodiak
Island and then turn eastward across the Gulf. This low will allow
for gusty west to northwest winds to set up across Kodiak Island
today as well as snow showers across parts of the Island. A winter
weather advisory is in effect for Kodiak Island as blowing snow
will create low visibilities mainly across southern and western
portions of the Island. 3 to 5 inches of snow is expected today
across this area. Meanwhile, an occluded front will move through
the Kenai Peninsula and into the northern Gulf today producing
strong winds across Turnagain Arm and south across parts of the
eastern Kenai Peninsula and into Prince William Sound. These winds
will combine with falling snow to produce blizzard conditions
across the eastern Peninsula especially for areas south of
Girdwood to Turnagain Pass and Portage Glacier Road east towards
Whittier. Most coastal locations will warm into the mid to upper
30s where rain will mix with snow this afternoon. As the front
moves onshore this afternoon through this evening the winds will
begin to decrease with rain or a mix of rain and snow developing
across the western Kenai Peninsula into Anchorage and the Mat
Valley, however no snow accumulation is expected. Snow will
continue across Prince William Sound tonight into Thursday as low
pressure across the Gulf creates lift and onshore flow. A trough
will swing into Southcentral on Thursday bringing another shot of
snow to the Peninsula and towards Anchorage and the Mat-Su valley.
Up to an inch of snowfall is possible as this features crosses
the area. Finally, as we head into Friday a shortwave trough will
move in from the west and bring another chance of light snow for
parts of Southcentral including Kenai, Soldotna, Anchorage and the
Mat valley where another inch or two of snow is possible. This
shortwave will push a cold front across the area Friday with
temperatures dropping as we head into the weekend.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3:
Today through Friday night)...

A deep low centered near Kodiak Island this morning will continue
to bring light snow to the Southwest mainland and strong winds to
the Alaska Peninsula through Thursday morning. A band of light
snow associated with a front pushing across the Aleutian Range
extends over the northern Alaska Peninsula and across the Bristol
Bay region, expected to bring several inches of snow from
Dillingham eastward through tonight. The heaviest snow totals are
likely to be around 3 to 5 inches along the northern Alaska
Peninsula between King Salmon and Pilot Point, with most other
locations in the 1 to 3 inch range. 25 to 35 mph winds will
combine with the snow to reduce visibility along the coast within
the same corridor through this afternoon, before the front begins
to push east, allowing snow to come to an end from west to east. A
weak front bringing light snow along the Kuskokwim Delta coast
will also swing eastward today and join up with the front over
Bristol Bay to bring 1 to 2 inches of accumulation to the Lower
Kuskokwim Valley. Behind this front, colder air moves in, dropping
temperatures into the single digits tonight for most locations.
Light snow hangs up along the Western Alaska Range and tapers off
through Thursday morning as the low in the Gulf of Alaska exits
eastward.

Then, there is increasing confidence in the development of a
compact low in the northern Bering Sea on Thursday. With
supportive upper-level dynamics, the low has the potential to
bring a brief round of gale force winds to the Kuskokwim Delta
coast as it tracks over the Y-K Delta Thursday afternoon. Combined
with a quick shot of snow, visibilities may briefly drop to one
half mile or less, but these conditions are not expected to be
sustained for more than a few hours. As the low tracks up the
Western Alaska coast, it will push a front that brings 1 to 2
inches of snow across the mainland Southwest through Thursday
night. Behind the front, a transient surface ridge moves in along
with another cold air mass. This will make for a relatively calm
and cool day, with highs in the low 20s, before a large low over
Chukotka pushes a warm front to the coast with another round of
light snow for Friday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Today through Friday night)...

A deep low centered near Kodiak Island this morning is drawing
cold air across the eastern Aleutians and Alaska Peninsula,
bringing widespread gales and snow showers through tonight. Gusts
of 60 to 70 mph will be possible through gaps and passes along
the Alaska Peninsula until the low departs into the central Gulf
of Alaska this evening and the strongest cold advection and
upper- level jet moves over the western Gulf coast. Westerly flow
and a cool airmass with embedded snow showers predominate for much
of the rest of the week. Winds subside below gale force for
tonight and Thursday across the Bering Sea. The one exception to
this could be a compact low developing in the northern Bering
Thursday morning and tracking into the Yukon-Kuskokwim Delta
Thursday afternoon, which may develop localized gales near the
center and is likely to enhance snow showers in its vicinity. By
Thursday night, a strong system begins to track along the coast
of Far East Russia and brings a surge of southerly gales and warm
air to the western Aleutians. Through Friday, this air mass
spreads across the Bering Sea, bringing rain to the central
Bering/Aleutians as the front slides eastward.

&&

.LONG TERM FORECAST (Days 4 through 7: Saturday through Tuesday)

A transient, but amplified ridge will build into Southcentral
Saturday bringing quieter weather through Sunday before another
Bering Sea front approaches in the latter half of Sunday and into
Monday. This creates another problem with possible precipitation
for Southcentral heading into the week due to the development of a
possible surface low in the Gulf. Models have been struggling to
define what exact impacts this aforementioned low will have. Out
west, conditions along the southern half of Bristol Bay and the
Alaska Peninsula should remain fairly quiet through Saturday.
Northern parts of Bristol Bay into the Kuskokwim Delta region
could get clipped by a Bering low pressure system's warm- front
the latter half of Friday into the day on Saturday, which paves
the way for light precipitation chances. The cold- front of this
Bering low will track into the western Bering and western
Aleutians Friday making it to the Southwest coast by Saturday
night into Sunday morning. Accompanying this front will be gale-
force winds with possible storm-force gusts, especially for the
western Aleutians. As the front progresses eastward throughout the
central and eastern Bering, winds will weaken mostly to low- end
gales to high-end small craft through Sunday morning. Southwest
looks to become unsettled late Saturday night into the day on
Monday as the front will cross the southern mainland then. There
are still a few timing differences regarding the progression of
the front through Southwest. However, the progressive pattern
looks to continue with no real sustained breaks in activity.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Blizzard Warning 125.
Winter Weather Advisory 171.
MARINE...Storm Warning 734 751.
Gale Warning 710 711 712 713 715 716 724 725 726 730 731 733 732 738
750 752 753 754 755 756 757 758 759 770 772 771 773 774 778 766 760
761 762 764 767 351 352 414.
Heavy Freezing Spray Warning 760 761 762 764 767.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ED
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CQ
LONG TERM...NS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
210 PM AKDT WED MAR 22 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0142 PM     SNOW             SEWARD                  60.10N 149.44W
03/22/2023  M14.0 INCH       KENAI PENINSULA    AK   PUBLIC

            THE SNOW IS EXTREMELY HEAVY DENSE SNOW.
            VISIBILITY IS LESS THAN A 1/4 MILE SINCE
            THIS MORNING AT 7:30 AM. ROAD CLEARING IS
            NOT KEEPING UP WITH SNOW FALL. FROM 1130 TO
            130 WE RECEIVED 4 INCHES.

&&

CJ