Gale Warning 126, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
413 PM AKST Tue Feb 26 2019

.ANALYSIS AND UPPER LEVELS...

The overall upper air pattern over the region is very stable as
the strong omega blocking high over the eastern part of Alaska
asserts its dominance. This has promoted very cold inversions from
Cook Inlet eastward, along with some local areas of fog in the
vicinity of Cook Inlet and Knik Arm. Over the Bering Sea, a
stalled baroclinic zone on the western side of the ridge is
keeping precipitation in place, mainly along the Kuskokwim Delta
and over the Eastern Aleutians at this time. Open cell cumulus has
moved over most of the Bering Sea behind a shearing out upper
level trough, within an area of broad cold air advection and
southwest flow. Finally, there is another strong warm front
lurking just south of the Bering Sea. The next low will move into
the Bering tonight, and will usher in more warm air and southerly
winds to the Bering as the storm track remains focused over that
area.

&&

.MODEL DISCUSSION...

The numerical models are clustered well and in excellent agreement
with the entire pattern through Friday as the main storm track
remains over the Bering Sea. The favored model was the GFS.

&&

.AVIATION...
PANC...Fog and stratus has largely dissipated around the Knik Arm
area, although it remains to the south around Cook Inlet. General
thinking is this fog and stratus will redevelop this evening and
become more dense than previous nights. This also means it may
last longer into the afternoon hours Wednesday.

&&

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

The upper-level ridge anchored over the northern Gulf will remain
the overall dominant weather feature for Southcentral through the
rest of the week. With the ridge now slowly drifting east,
this is allowing the flow in the lower and mid levels to become
more southerly in the region from Kodiak Island north through
Cook Inlet. This can be seen in the low stratus hanging over the
southern half of Cook Inlet. These clouds, however, have had a
difficult time moving north of Kalgin Island over the past day and
half and will continue to do so through the overnight hours, even
with a weakening down-Inlet flow. Given this, fog is expected to
redevelop from Kenai north across the Anchorage Bowl and into the
southern half of the MAT-SU valleys overnight. A weakening
shortwave trough then moves overtop the ridge late Wednesday,
spreading some mid and high clouds across Southcentral. This
trough will act to temporarily suppress the ridge and weaken the
pressure gradient responsible for the outflow winds of previous
days. Areas of fog are still possible across the Cook Inlet
overnight Wednesday into early Thursday, although most likely not
as widespread as tonight due to the influence of the trough. The
trough then retreats north by early Friday as the ridge builds
back in.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2/Tuesday night
through Thursday)...

A weak front continues to persist along the southwest coast as a
blocking high to its east is preventing it from moving anywhere.
We are still expecting the front to fizzle tomorrow. This front
will quickly be replaced by another front late Thursday as the
eastern edge of a front in the Bering scrapes along the coast.
This front will attempt to push inland, but once again will be
blocked by high pressure to the east. Southerly flow ahead of the
front will bring windy conditions right along the coast and an
increase in temperatures. High temperatures are expected to warm
into the upper 30s in most areas and the lower 40s on the AKPen.
Other than warming temperatures, the interior of SW Alaska will
remain quiet due to the influence of the high to the east.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2/Tuesday
night through Thursday)...

The forecast is coming together for the two low pressure systems
moving into the Bering from the south. Models are depicting the
pattern well and satellite imagery is indicating both systems are
on track. Cloud cover associated with the first low is seen on
satellite over the western Aleutians as of Tuesday afternoon. The
center of this first low will cross the western Aleutians
tonight. The second will enter the Bering tomorrow night and still
looks to be the stronger of the two systems; it becomes a closed
and well- wrapped low as it travels north through the Bering. As a
result, storm force winds have been maintained on the leading
side and added on the back side of the low as it spins through the
Bering.

Models have also moved the low center to the west, so this is
reflected in today's forecast as well. This moves the core of
winds and precipitation slightly to the west. Many of the same
areas will still be affected, as the swath of gale force winds
and precipitation is quite large with both systems. The quick
succession of both lows also means gale force winds will be
sustained in the Bering until the second low's exit late Thursday.

&&

.MARINE (Days 3 through 5)...

Lighter winds and lower seas are expected across the Aleutians
Thursday afternoon through Friday as a low departs to the north.
Models are still in slight disagreement regarding the position of
a strong low moving into the western Bering on Saturday, however
no matter where it is centered, there is good agreement that
widespread gales and possibly storm force winds will track across
the western half of the Aleutians over the weekend before
diminishing over the eastern Aleutians as the front runs into a
large blocking ridge over the mainland.

Sub gales continue over the Gulf through the weekend under a
strong ridge.

&&

.LONG TERM FORECAST (Days 3 through 7)...

Fair skies are likely across the Aleutians Friday as a low
departs to the north. As mentioned above, despite model
disagreement on the placement of the incoming Bering low, moderate
precipitation (mostly rain) will track west to east over the
western Aleutians this weekend and slowly over the eastern
Aleutians Monday and Tuesday as the progress of the associated
front is impeded by a strong ridge over the mainland. Partial
clearing with westerly flow will build in behind the front.

A strong ridge will bring generally fair skies through the weekend
over southern Alaska. The previous GFS run showed an amplified
trough over Southcentral on Sunday, however the latest run now has
it further east, aligning more with the ECMWF. In any case, this
would only bring more cloud cover as any associated precipitation
would quickly deteriorate as it runs into the drier ridge.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale 155 165 171 175 177 180-185.
		 Storm 170 172-174 176 179.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...JA
SOUTHCENTRAL ALASKA...TM
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BJB
MARINE/LONG TERM...AP/KVP