Small Craft Advisory 51, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
705 AM AKST Tue Jan 14 2020

.ANALYSIS AND UPPER LEVELS...

The general pattern consists of an upper level ridge in place
over the Bering with a broad trough in place over Siberia and a
second trough in place over the Alaska Panhandle. At the surface, a
storm force front over the western Aleutians continues to move
eastward while a departing low in the Gulf continues to draw out
gusty offshore winds across the Gulf coast. A few weak upper level
waves passing over Southcentral have generated intermittent flurries
overnight.

&&

.MODEL DISCUSSION...

Model solutions remain in good agreement for the near term. There
is especially good consistency regarding the ridge over the Bering
amplifying midweek. Upstream of this ridge, there is some
inconsistency regarding the track and strength of a secondary low
that forms along the storm force front as it traverses the Bering.
Overall, forecast confidence is average.

&&

.AVIATION...
PANC..Low level stratus and fog in place over Cook Inlet will
persist over the terminal this morning. Conditions should improve
to VFR by the afternoon.

&&

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

An upper ridge is building east across Southcentral. Subsidence
under the ridge is trapping low level moisture and producing areas
of stratus and patchy fog over Cook Inlet and inland areas across
Southcentral. Conditions should improve today and are not likely
to be as widespread tonight as northerly low level winds will
provide for more mixing. Offshore flow and gap winds across the
eastern Kenai Peninsula and northern Gulf will be enhanced by
supporting northerly upper level flow with the building upper ridge
and cooling of 850 mb temps. Winds over the eastern Kenai
Peninsula will diminish on Wednesday as the orientation of the
flow (gradients) become less favorable. Outflow conditions,
however, will remain fairly strong across the northern Gulf
especially out of the Copper River Delta, Thompson Pass, and the
Valdez public zone and surrounding marine areas. Winds in these
areas will peak during the day on Wednesday. Gap flows across the
Matanuska Valley and Broad Pass areas are expected to develop
tonight and continue through Wednesday. Cooling temperatures will
likely keep wind chills in the 40 to 55 below range through
Thompson Pass. Wind chills tonight through Broad Pass are expected
to drop into the minus 30s.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tuesday
through Thursday)...

High pressure is moving over Southwest AK as expected. Some patchy
low level cloud cover still exists over the area. Northwesterly flow
off the Bering Sea will continue this patchy cloud cover at least
through the morning hours. Otherwise, quiet weather with slightly
cooler temperatures under high pressure is expected through Thursday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Tuesday through Thursday)...

The eastern Bering/Aleutians remain quiet with high pressure in
place. The western Bering/Aleutians are beginning to feel the
effects of the large storm force low forecasted for the area
today. This low will slowly track east over the next couple of
days, its progress impeded by the high pressure to the east. The
front should be over the central Aleutians tomorrow and eastern
Aleutians Thursday. On Wednesday, the front redevelops and
maintains storm force winds over the central Bering/Aleutians.
However, it will decay Thursday as it reaches the eastern Bering.

&&

.MARINE (Days 3 through 5)...
Thursday through Friday the main focus for gale winds are
expected over the Bering as a front slowly lifts north. There is
potential that winds could be stronger Thursday morning across the
Aleutians, however model uncertainty remains high. The next low
to monitor for the Gulf develops across the eastern waters on
Saturday night and then tracks northwest into Sunday.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Dry and cold conditions are currently forecast across the Southern
Mainland Thursday night through the beginning of next week with
active weather mostly impacting the Bering. There is a bit of
uncertainty between the models, so the forecast was trended toward a
blend of ensembles which increases precipitation across the eastern
Bering and Gulf during the upcoming weekend.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Chill Advisory 131, Flood Advisory 121.
MARINE...Gales: 127, 130, 131, 132, 137, 138, 150, 155, 165, 176,
180, 181.
Storms: 170-175, 177-179, 185, 411-414.
Heavy Freezing Spray: 119, 121, 126, 127, 129, 139, 160, 180.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...KO
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BJB
MARINE/LONG TERM...KH