Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 251158
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
358 AM AKDT Sat Mar 25 2017
.ANALYSIS AND UPPER LEVELS...
Dominant high pressure remains over the Bering with a trough to
the east stretching through Southcentral Alaska. This setup has
brought showery conditions to the Gulf but the majority of the
southern mainland is seeing no precip. Outflow winds also continue
under this pattern with areas from Cook Inlet west continuing to
see clear skies. West of the ridging a front has stalled over the
Central and Western Aleutians and is bringing gale force winds to
The models are in good agreement in the short term but are
struggling with low placement with lows approaching the area in
the mid term. One of the lows moves towards the Eastern Aleutians
Sunday afternoon then the models have various tracks of the low
with the NAM being the most middle ground solution. Another low
tracks into the Gulf Sunday night where the models have a somewhat
similar track but are struggling with timing as it moves towards
the Kenai Peninsula.
PANC...VFR conditions and light winds will persist.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
An upper level trough continues to be the dominate feature over
Southcentral Alaska through the weekend. Look for the threat of
snow showers to continue along the Gulf coast and Copper River
Basin through Sunday night. Snow showers will likely spread west
across the Gulf, affecting Kodiak Island and the eastern Kenai
tonight and into Sunday. Otherwise, continued offshore flow with
mostly sunny skies for the Anchorage Bowl through today before
some mid-to-high clouds move into the area by Sunday. Meanwhile,
the gradient begins to weaken across much of the region this
afternoon, so gap flows across the MatSU valleys, and north
Gulf/eastern Kenai should start to weaken. Gradients increase
again Sunday night, so expect an up tick in gap flows.
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Outside of some possible cirrus clouds along the Kuskokwim Delta
coast, cloudless skies remain the theme of the forecast in
Southwest Alaska. The atmosphere continues to remain bone dry at
all levels. Thus, despite the presence of a persistent 80 kt
northerly jet over the area which normally would transport
cloud cover through the upper-levels from great distances, the
dessicated atmosphere will continue to make for full sunshine
during the day and excellent star-gazing at night. The westward
retreat of upper level ridging and advance of a trough over the
weekend will reinforce the cold, dry air over the area. As a
result, high temperatures will drop a couple degrees each day for
the next few days area-wide. The winds will stay breezy enough to
continue to hold lows above 0, though wind chills will generally
drop to between 5 below and 15 below at night.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Much like executing effective defense in a boxing ring, the
upper-level pattern over the Bering will trade one block for
another as a disintegrating omega block quickly transitions into a
rex block over the next couple days. Ridging aloft over the
northern Bering will move north of a persistent low and associated
troughing south of the Aleutians. The result will effectively be
more of the same. Steady easterly winds will persist over much of
the Bering between the high over the northern Bering and the lows
south of the Aleutians. One change from previous forecasts is the
Bering high now looks to be strong enough to keep much of the
moisture associated with the low south of the Aleutians, with only
widely scattered shower activity at most now expected in the
eastern Aleutians on Sunday. Off-and-on rain will also continue
for the central and western Aleutians through the weekend
associated with the frontal boundary between the high over the
Bering and the lows over the North Pacific.
.LONG TERM FORECAST (Days 3 through 7)...
Ridging over the Bering will slowly retreat to the north as a
front slides north across the Aleutian chain through the end of
the weekend. Real change continues to be advertised by all models
early into next week. All guidance has shifted the focus of a low
that would have only impacted the panhandle to bringing the low
much farther north and into the Gulf. There are still some pretty
sizable differences amongst the guidance types that detail how
strong this low will be and what, if any, precipitation may fall
across the Anchorage area. At this time, confidence is too low to
go any higher than a slight chance of snow. The bottom line is
that the pattern is now on the verge of change and the days of
cold and endless sun are going on a brief hiatus. The longwave
patter undergoes a bit of a shift following this early week system
and will set us up to be in a little bit of a favorable pattern
to see systems beyond the forecast timeframe reaching all of
MARINE...Gales...155 172 173 174 175 177 178.
Heavy Freezing Spray...185.
SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JW