Gale Warning 278, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
438 PM AKDT Mon Mar 16 2020

.ANALYSIS AND UPPER LEVELS...
The high pressure over the Gulf and Southcentral remains today,
but is weakening and moving southeastward away from the region.
A weak trough along the north Gulf of Alaska coast is a small
feature, but important enough to keep those gap winds from Seward
through Prince William Sound going today.

A low south of the Alaska Peninsula and associated front will
move over Kodiak tonight and into Southcentral tomorrow. The large
low is still a bit southwest of Attu but will move into the
Bering Sea Tuesday night and become the main weather feature out
west the remainder of the week.

&&

.MODEL DISCUSSION...
Models can now be considered in very good agreement with forecast
confidence increasing. Even the precipitation-type questions over
Southwest Alaska are becoming more clear with the latest model
runs.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist through Monday
night. Snow will move into the area Tuesday bringing MVFR or IFR
conditions to the terminal in the afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
High pressure remains in place over Southcentral AK. However, a
weak area of low pressure will push northeastward from Kodiak into
the Southcentral coast tonight into tomorrow night. This will
induce a barrier jet and turnagain arm winds. Recent model runs
show the barrier jet will be stronger than initially forecast, so
we upped barrier jet strength. Southcentral can continue to
expect light precipitation out of this system as well. Most
locations will remain cold enough to see snow, however it will be
warm enough along the coast of the southern Kenai for places like
Homer to see rain. Overall, the forecast looks to be on track so
little change was made. Confidence is high with good model
agreement with this system.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
An area of low pressure currently centered south of the Alaska
Peninsula will drift northward and inland over the Bristol Bay
region. As the leading warm front moves in over Southwest Alaska,
expect warming temperatures and widespread precipitation. The main
forecast challenge continues to be precipitation type. A mix of
snow and potentially freezing rain will begin at the onset tonight
followed by a change to rain Tuesday as temperatures continue to
warm. As an upper level trough moves over the area late Tuesday,
colder temperatures will be reintroduced at the mid-levels,
allowing for a return to snow, especially over the Kuskokwim Delta
area Tuesday evening.

Any lingering precipitation will taper off by Wednesday as an
upper level ridge moves in over Southwest Alaska. A frontal
system associated with a storm force low moving north toward the
Gulf of Anadyr will bring the area another round of wintry weather
beginning Wednesday night and continuing through Thursday
afternoon. Areas north of Dillingham and King Salmon will remain
all snow at this time as temperatures will be falling at 850mb as
the precipitation is moving through. Areas south will remain
mostly rain with the an area of rain/snow mix possible near
Egegik.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
Weak, unorganized flow across the Bering is keeping stratus and
low level moisture in place, especially over the Pribilof Islands.
A ridge of high pressure builds over the area for Tuesday
morning, allowing low level stratus and fog to persist.

Meanwhile, a storm force low over the North Pacific will continue
moving northward early Wednesday morning with the center
remaining west of the western Aleutians and western Bering Sea.
Strong cold air advection on the backside of this low will bring
strong gusty winds to the region as a result. Therefore, storm
force winds were introduced in this forecast package for Wednesday
afternoon and evening over the western Aleutians. Winds will
begin to slowly subside early Thursday but still remain fairly
gusty with gale force winds expected through Thursday afternoon
and evening before subsiding further to small craft advisory
level.

The aforementioned low pressure will send a cold front through the
central Bering and central Aleutians Wednesday morning along with
strong southerly winds. This front will continue moving eastward
with a faster timeline expected for the Pribilof Islands.
Therefore, pops were increased to the likely category a few hours
earlier. All rain is expected with this front as plenty of warm
air will be in place as the front pushes through. Behind the
front, cold air advection will take over which will create gusty
winds on the backside of the low.

&&

.MARINE (Days 3 through 5 Thu through Sat)...
On Thursday morning a front associated with a low in the eastern
Bering will enter the western Gulf bringing with it small craft
winds. There is low confidence that another triple point low will
form in the northern Gulf Thursday night. If it does, expect gale
force winds to occur through channels including Shelikof Strait,
the Barren Islands and through gaps and passes on the Pacific side
of the Alaska Peninsula through Saturday morning.

A gale force front over the Bering will continue to push
northeastward through Thursday before it exits the Bering
Friday. There is moderate confidence that another front will enter
the western Bering Friday night. Depending on the strength and
track of this front, gale force winds will be possible in the
western Bering through Saturday.

&&

.LONG TERM FORECAST (Days 3 through 7 Thu through Tue)...
Models continue to show good agreement that an upper level ridge
that extends from the Gulf north across the state, will continue
eastward into Canada on Thursday. Upstream, ahead of a large
Bering low, a strong front moves eastward across western Alaska
and the Peninsula. This front will impact the southwest coast
Thursday into Friday, bringing precipitation and strong southerly
flow. The track of this low still remains uncertain, though models
are showing the center departing the Bering to the north by
Friday. This will be followed by another upper level ridge moving
across the Bering and into southern Alaska through Sunday. Similar
to last week, warm temperatures and moist conditions will advect
into the Aleutians and Bering following the backside of the ridge.
This pattern will continue to alternate through Tuesday as upper
level troughs and ridges continue to follow one another across the
Bering.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 173>178 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...BB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KO/MV
MARINE/LONG TERM...CK