Brisk Wind Advisory 22, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
512 AM AKST Sat Jan 22 2022

.ANALYSIS AND UPPER LEVELS...

Southern Alaska sits between a longwave trough stretching over
the Bering into the Northwest Pacific and a longwave ridge
extending northward from the Northeast Pacific into Western Canada.
As a result, broad southerly flow continues to direct several
lows and shortwaves northward into the state along with warm,
moist air. One of these shortwaves is presently lifting across
Southern Alaska, bringing another round of precipitation to
Southcentral. With a warm layer of sufficient depth and above
freezing temperatures at the surface in place across Southcentral,
this precipitation is falling widely as rain along the north Gulf
coast and the Cook Inlet region. At elevation, the coastal
mountain ranges continue to wring out this moisture as snow.
A chinook also developed along the western slopes of the Chugach
Mountains overnight, where adiabatic compression of downsloping
air warmed temperatures into the 40s from the Kenai Peninsula to
the Mat-Su.

A low south of the AKPEN is also feeding warm air into the
Southwest, where precipitation is falling as rain in the Bristol
Bay region east of Dillingham. Snow is occurring across the rest
of Southwest Alaska. Temperatures are falling in the Kuskokwim
Delta as a low in the northern Bering wraps cold air behind it
into Western Alaska. Across the Bering, northerly flow continues
to bring scattered snow showers to the Aleutian Chain and the
Pribilof Islands.

&&

.MODEL DISCUSSION...

Models remain in good synoptic agreement through the short term.
The timing and placement of upper-level shortwaves tracking
northward through the broad southerly flow is in good agreement
through Sunday, although minor differences on timing of
shortwaves tracking across Southcentral contribute to uncertainty
in the timing of various rounds of light rain in the Cook Inlet
region through Saturday night. Another challenge is the resultant
timing of the Turnagain Wind bending in and out of Anchorage in
the short term.

On Sunday, there is some model discrepancy with the strength and
timing of the next low and shortwave as it heads towards Southern
Alaska. This results in decreased confidence and increased
uncertainty regarding the potential for freezing precipitation
over Southwest Alaska, as well as the potential for high winds
along Turnagain Arm and higher elevations.

&&

.AVIATION...

PANC...Intermittent rain showers will be possible which may lower
ceilings below 5000' at times, though ceilings are expected to
remain VFR through the TAF period. While timing is somewhat
uncertain, southeasterly winds are expected to diminish through
this morning and become light out of the north by this afternoon.
Gusty southeasterly winds may return once again after midnight,
but should begin to diminish late Sunday morning.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

Due south upper level flow is over the entirety of Southcentral
Alaska, bringing in warm and moist air to the region. The story
the next few days will be this warm, moist flow aloft and
downsloping over the lee side of the different mountain ranges.
After a shortwave moves through this morning, the lee sides of
the mountains should see little or no precipitation through
Sunday, with the windward sides of coastal mountains ranges
getting steady rain at sea level.

The strong winds through Turnagain Arm will persist through
Monday with the strongest winds occurring Sunday evening through
Monday morning. There is a chance that they could gust up to 75
mph along Turnagain Arm and higher elevations of the Anchorage
area during that time. Therefore, a High Wind Watch is in effect.

A strong front that is associated with the next low moving toward
the area will track over Kodiak Island Sunday afternoon through
the overnight hours bringing strong winds and heavy rain to the
island.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

The Bethel and King Salmon radars have been busy early this
morning. The active pattern will continue today as the remnants
of a frontal boundary move inland. Southwest Alaska will get a mix
of precipitation including rain, freezing rain, and snow. The
expectation is that where freezing rain forms, the accumulations
will be light. Sunday there will be a lull between systems. On
satellite imagery, there is a new low with a fetch of tropical
moisture that extends back to the Mariana Islands. The models
bring the leading edge of this system into Bristol Bay Sunday
night. Expect another wintry mix from this system complete with
freezing rain.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

The Bering will remain relatively stagnant, all of the action is
in the North Pacific the next several days. With the longwave
ridge centered over the Gulf and the East Pacific, the corridor
for the low tracks will set up over the central and eastern
Aleutians. Back to back North Pacific lows are expected this
forecast period, so expect heavy rain at times for the eastern
Aleutians. The northern and central Bering will be under the
influence of an Arctic airmass, with heavy freezing spray and
isolated convective snow showers possible.

&&

.MARINE (Days 3 through 5 - Monday through Wednesday)...

Gulf of Alaska...A well developed Bristol Bay low moves to the
Northern Gulf of Alaska for Wednesday. Its front moves across the
Gulf by Wednesday. Forecast confidence is fair due to the low
track by Wednesday. Southerly gales ahead of the front become an
easterly gale force barrier jet along the North Gulf Coast for
Tuesday, and northwesterly gales along the Alaska Peninsula coast
for Tuesday and Wednesday. Seas to 22 feet from the Alaska
Peninsula across the western Gulf, subsiding Tuesday, and to 15
feet east of the Barren Islands, subsiding Wednesday.

Aleutians / Bering...A well-developed Bristol Bay low moves
inland late Monday. Northerly gales move across the Alaska
Peninsula by late Monday. Seas to 22 feet on the Pacific side of
the Alaska Peninsula, subsiding. Forecast confidence good through
the period. Areas of weak low pressure with gusty winds move
across the Bering through Wednesday. A well developed North
Pacific low intensifies as it approaches the Western Aleutians.
Widespread high end gales with areas of possible storm force winds
spread into the Central Aleutians and southern Bering through
Wednesday. Seas building to 18 feet on the Pacific side of the
Aleutians by Wednesday.

&&

.LONG TERM FORECAST (Days 4 through 7: Monday through
Thursday)...

The pattern will remain amplified during the extended period with
upper troughing extending across Southcentral and Southwest
Alaska on Tuesday while upper ridging builds across the eastern
Bering/Aleutians. The upper trough will then move eastward on
Wednesday and Thursday across Southwest and Southcentral as upper
ridging builds in the wake. Then, the upper level ridging will
extend across the eastern Bering/Aleutians, Southwest and
Southcentral Alaska by Friday. Upper level troughing will continue
to extend across the far western Bering/Aleutians during the
extended period. This means the extended period will start off
cold for Southwest Alaska and gradually become warmer as the
ridging builds across the area. Southcentral will remain cold for
a longer period of time as the ridge-axis is expected to remain
west of the area which will allow for northwesterly flow (cold air
advection) aloft. This pattern is also conducive to sunny skies
during the day and clear skies at night. This results in colder
overnight low temperatures across Southcentral due to radiational
cooling.

A weakening surface low is expected to move northeastward from
the Gulf into Yukon Territory on Tuesday and result in a chance of
light snow for Southcentral Alaska. The next chance for snow will
be on Thursday as a second low moves into the northern Gulf of
Alaska. Forecast confidence remains low at this time with snowfall
amounts due to significant differences in the placement of this
low.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Watch 101.
MARINE...Gale Warning 130 132 150 172 352.
         Heavy Freezing Spray Warning 185 414.

&&

SYNOPSIS AND MODEL DISCUSSION...CQ
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...KZ/ED