Gale Warning 733, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
733 AM AKST Mon Dec 16 2019

.ANALYSIS AND UPPER LEVELS...

A broad area of low pressure continues to spin in the western
Gulf of Alaska and slowly decay. The weakening occluded boundary
with this system continues to be stalled out along the gulf coast.
Due to the orientation of the front, the Kenai Mountains are
blocking any precipitation into the Anchorage Bowl area and the
Chugach are preventing weather from moving inland.

In the Bering, a large and disorganized low pressure system is
pushing through the western and central Aleutians. This system is
producing rain and gale force winds as it progresses east. A weak
ridge of high pressure is over the eastern Aleutians, trapping low
level stratus beneath it. Meanwhile in southwest AK, light showers
are moving through the area on the northwest side of the low in
the western gulf of AK.

&&

.MODEL DISCUSSION...

Models continue to be in good agreement. Therefore, forecast
confidence is high and minimal changes are needed.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

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

The weather pattern for Southcentral Alaska and the Gulf of
Alaska is not changing much. The main low remains southwest of
Kodiak Island. The front has stalled across the north Gulf coast
and will weaken today. It is still bringing rain and snow
(depending on elevation) to the coastal locations though
precipitation type will start to trend more toward snow as upper
level flow turns more to the northeast by Tuesday and allows cooler
air to move over the region. This will also start a cooling trend
for most of Southcentral Alaska for this week.

&&

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

The weather pattern across Southwest Alaska is not expected to
change much through Tuesday. A stalled out front over the area
will continue dissipating today. A few flurries and sprinkles are
possible, but the cross-mountain flow should continue to keep any
precipitation few and far between. Meanwhile, more broadly, an
area of polar high pressure will persist over interior northeast
Alaska, while Pacific low pressure systems track along the
Aleutians and south of the Alaska Peninsula. This will keep the
winds out of the north to northeast, or offshore, through Tuesday
and beyond. In effect, this will keep precipitation chances low,
the chance for fog low, and will result in a cooling trend in the
temperatures with time, as increasingly colder air is drawn
southwestward out of the interior. The coldest air will hold off
until late week.

&&

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

A Pacific low is tracking across the Central Aleutians this
morning. Gale force northeasterly winds are ongoing along with
mostly snow falling across the Western Aleutians. That front will
diminish today as the parent low dissipates and a series of
triple-point lows develop on the Pacific side of the Aleutians by
tonight. The low will strengthen south of the Alaska Peninsula,
which will increase the northerly winds all across the Bering.
This should return the Bering back to a broken clouds and frequent
snow showers weather regime as opposed to the fronts and
widespread stratus that are currently occupying the Bering.

As cold air continues to stream southward behind the low, a brief
period of storm force winds are possible over the Aleutians near
the International Date Line today. After that, the winds will
gradually diminish and shift eastward towards Adak on Tuesday.

&&

.MARINE (Days 3 through 5)...
At the onset of this forecast period there are two lows,
one near Kodiak Island and a Kamchatka low. The low near Kodiak will
push into the Gulf of Alaska bringing small craft advisory
conditions and possibly a few gales. The Kamchatka low will move
into the Bering bringing widespread storm force winds that will
taper down towards the end of the period. Anticipate light to heavy
freezing spray from Hooper Bay to Nunivak Island.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The global models are in decent agreement with the main synoptic
pattern for north Pacific and Bering through Saturday December
21st. At the onset of this forecast period, there are two surface
lows. One is near Kodiak Island and a Kamchatka low. There is a
ridge axis between the two systems. There are some minor differences
with the timing of two surface lows. There is another noteworthy
feature...a piece of arctic energy gets kicked out from an upper low
well north of the Brooks Range and tracks into southwest Alaska.
Then a second arctic impulse dives southward and the models bring
this feature south of the Alaska Range. Expect cooler temperatures
from SW AK to the Copper River Basin. At this point, Saturday looks
brutally cold for southcentral AK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORMS: 177
         GALES:  130 173-176 178 411 413
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BJB
SOUTHCENTRAL ALASKA...JW
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...EZ
MARINE/LONG TERM...PJS