Small Craft Advisory 121, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 AM AKST Wed Feb 7 2018

.ANALYSIS AND UPPER LEVELS...
A broad upper level ridge along the Northwest coast is beginning
to sag southward while a broad trough over the western Bering
sends a closed low toward the central Aleutians. The front across
the northern gulf that brought snow on Tuesday has diminished with
only a remnant circulation across the northeast gulf. Scattered
showers continue to develop around the weak surface low mainly
across the northern gulf waters. Winds are calm in the wake of the
fronts that spanned across the southern mainland yesterday which
is allowing patchy dense fog to develop as a stable air mass re-
establishes across the southern tier. The exception to this is
where the unsettled weather pattern persists across coastal areas
of the eastern Kenai and Prince William Sound.

&&

.MODEL DISCUSSION...
Models are in good general agreement through the end of the week
as the pattern slowly shifts. The upper level ridge remains
dominant across the mainland although its center tracks toward
the southeast. The upper level trough over the Bering keeps an
active pattern over the Bering as it swings several strong waves
up from the North Pacific.

&&

.AVIATION...
PANC...Periodic MVFR/IFR ceilings and visibilities are possible
this morning as low level stratus and fog develops across the
Inlet waters and shifts along the coast. Conditions should
improve quickly by late morning as dry offshore flow sets up.
Light winds prevail through the TAF package.

&&

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

The radar at Middleton Island (PAIH) still has light showers on
it from Montague Island to Cordova. The most recent scatterometer
pass from the satellite has an elongated circulation near
Middleton Island and the low is expected to slowly decay. There
has been some fog detected along the Kenai Peninsula and Cook
Inlet. In the wake of the recent frontal passage, northerly flow
will influence Southcentral. A shortwave moving down from the
Yukon Territory will clip the region, enhancing the offshore flow.
The models continue to bring a ridge axis over Kodiak Island on
Thursday. After the fog and stratus clear out of the region,
expect chilly morning temperatures again.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Dry conditions and a cooling trend will dominate the next couple
days as an upper level ridge builds overhead. With steep surface
inversions in place (as seen in the 12Z King Salmon and Bethel
soundings), areas of fog and stratus will persist. A front will
approach from the southwest late Thursday, leading to increasing
offshore winds along the coast.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A high amplitude pattern will remain firmly entrenched across the
Bering Sea and Aleutians the next couple days with a trough over
the northwest Pacific and Bering Sea and a ridge along the west
coast of mainland Alaska. Lows will eject out of the trough,
tracking across the Aleutians and into the Bering Sea.
Persistently strong southerly winds will affect the Eastern
Aleutians, southern Alaska Peninsula, Pribilof Islands, and
eastern Bering Sea. Temperatures will generally be quite mild,
supporting rain in most places. The one exception will be the
western Aleutian islands where colder air moving in from the
west will lead to a mix of rain and snow.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Long term forecast starts in Friday with a ridge remaining over
mainland Alaska and a moderate low pushing into the eastern Bering
Sea from the south. This will set up a front with a tight
pressure gradient over Southwest Alaska and strong warm advection
which will bring temperatures into the 40s in parts of Southwest
Alaska coastal regions. Clouds will have a harder time moving into
Southcentral Alaska due to the strength of the ridge keeping the
front over Southwest Alaska at bay. This should allow colder
temperatures to persist into Saturday morning before temperatures
warm up later in the weekend as the ridge over mainland Alaska is
finally pushed eastward.

After this, things become a bit more uncertain. Due to the lack of
model consistency, ensembles were used to get an idea of the
general trend for next week with details remaining elusive. In
general it looks like a more progressive weather pattern is in
store for the area early next week with more mild temperatures. As
some fronts move through the region there is the chance for some
precipitation with each one, but nothing at this point looks very
certain so nothing more than 'chance of' POPs are being used in
that time frame over southern mainland Alaska from late in the
weekend onward.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning 127 155 165 170 171 172 173 174 175 176 179
                      180 181 185.

&&

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...PJS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...SEB
LONG TERM...EZ