Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 291217
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
417 AM AKDT MON AUG 29 2016
.ANALYSIS AND UPPER LEVELS...
Clear skies remained overnight as northerly/offshore winds
continue to bring unseasonably warm and dry conditions to the
South Mainland. These winds are being forced by a trough of low
pressure that has setup in the Gulf of Alaska, providing enough of
a pressure gradient to bring gusty winds to many gap wind areas of
the Gulf. The gradient is also beginning to be enhanced by some
low level cold air advection into the Copper River Basin, allowing
for gusty outflow winds to continue through the overnight hours in
places like the Matanuska Valley and Valdez area. Over the Bering
a broad low complex continues to bring periods of rain and low
stratus from the Pribilof`s westward as broad southerly winds flow
into high pressure that persists over the Eastern Bering.
With little overall change in the weather pattern into mid week,
the models remain in very good agreement through the short term.
The primary challenge continues to be around small differences in
weak lee side troughs that will develop along the North Gulf
coast. This is bringing some uncertainty into the timing of the
wind forecast for gap wind areas, but overall forecast confidence
remains good into Wednesday. Over the Aleutians the models have
come into better agreement on the track of the low to skirt the
Western Aleutians on Tue-Wed, improving forecast confidence in
that system and allowing winds to be increased slightly.
PANC...The timing and strength of N winds will be the forecast
challenge again this morning. The down-inlet gradient should begin
to diminish later this morning, allowing for light NW-SW winds to
develop for the rest of the day. The gradient will increase again
late tonight, causing N winds to increase again and continue into
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
More dry and sunny weather is on tap for the next couple of days
over south central Alaska as the mean upper level ridge position
remains just west of the area. Offshore flow will continue, with
gusty winds in some areas. High temperatures will likely be drop
a few degrees today and then a few more on Tuesday as some cooler
air pushes in with the northerly flow. However, temperatures will
still be well above normal, with some daily records likely to fall
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A dry offshore pressure gradient will remain dominant through
Tuesday as a northerly flow regime aloft remains across Southwest
Alaska. Some low sea stratus and fog will linger over the coastal
regions of the Kuskokwim Delta through this morning, then give way
for drier and warmer conditions to build in over the area through
mid-week. Winds over parts of the mainland will remain gusty at
times but will fluctuate in strength, as the the gradient
tightens this afternoon/evening and begins to loosen up by
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A low pressure system south of Adak will remain the main feature
of interest, as largely weak flow remains over the Bering Sea.
The remnants of a weak upper level warm front have allowed for
continued light rain and widespread fog from the Pribilof Islands
to Dutch Harbor. This area of light precipitation and fog will
remain in place through this morning before lifting north and
falling apart by this evening. A shortwave trough wrapping around
the parent low center in the North Pacific will lift north into
the western and central Aleutians early Tuesday morning/afternoon,
spreading rain and small craft southeasterly winds into the area.
The eastern Bering will remain on the quieter side as high
.LONG TERM FORECAST (Days 3 through 7)...
Offshore flow through the troposphere will keep Southcentral
Alaska in a warm and sunny weather regime through the end of the
workweek. High pressure ridging aloft begins to dissipate to the
northwest by the end of week, with the entire region increasingly
becoming influenced by cyclonic flow associated with a Bering low.
This will likely result in some increasingly high cloudiness with
offshore flow becoming weak.
This aforementioned Bering low will be near the Western Aleutians
mid-week and push a front north and east across the central and
southeastern Bering and associated island regions before
diminishing as it approaches Southwest Alaska next weekend. The
main impacts will be winds no higher than low-end small-craft
advisory level along with some rain. This rain looks poised to
reach the Southwest mainland Friday or early Saturday with the
diminished front. Rain is likely to spread to the northern Gulf
Coast and Prince William Sound by later Saturday into next Sunday.
With the main jet activity remaining south of the Alaska mainland,
weather systems should have a difficult time moving inland into
the southern mainland.
SYNOPSIS, MODEL DISCUSSION, AND AVIATION...DEK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP