Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 121213
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
413 AM AKDT Wed Jun 12 2019

.ANALYSIS AND UPPER LEVELS...

The afternoon weather map is dominated by high pressure spanning
the interior of Alaska and two low pressure systems south of the
mainland and Aleutian Chain. The first is the ever present low slowly
wobbling itself to death in the Gulf of Alaska. Outstretched to
its northeast is a front bringing showers to Prince William Sound
and eastern Copper River Valley. South of Shemya is the second of
these two low pressure systems. A front attached to this low is
bringing wind and rain to the central Aleutians today.

&&

.MODEL DISCUSSION...

Models are in excellent agreement through the end of the work
week. All models handle the evolution of the NPac low as well as
the de-evolution of the Gulf of Alaska low similarly. Differences
amongst guidance aren`t outwardly apparent until the weekend as
models are struggling with how the Pacific jet interacts with
this low. The biggest struggle is when and where energy will be
ejected around the base and where low pressure will form at the
surface.

&&

.AVIATION...

PANC...VFR conditions will persist through the forecast time
table. Turnagain winds will pick up this afternoon and will bend
over the airfield later into the early evening hours. Winds will
abate into the evening. Thunderstorms are likely again over the
Chugach as daytime heating peaks this afternoon, but are not
expected to move over or near the airfield.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2/Today
through Thursday night)...

A weak front along the north Gulf coast and upper level low aloft
will continue to bring waves of showers to the Prince William
Sound region and southern Copper River Basin this morning. Activity
will then diminish this afternoon as these features dissipate and
upper level flow shifts to northerly as a weak ridge nudges in
from the north and west. Meanwhile, remnant showers from the
Talkeetna Mountains and southwestern Copper River Basin will drift
across the Matanuska Valley and Anchorage early this morning
before finally dying out. Most of Southcentral will start out
mostly cloudy as much of the "debris" clouds from yesterday`s
convection tracks slowly southward across the region. However,
do expect sun to begin to break through by afternoon. The thermal
trough will shift further inland today thanks to intrusion of more
stable air along the coast. Most of the shower and thunderstorm
activity this afternoon and evening will be confined to the
Susitna Valley and Copper River Basin.

Tonight will once again see some clouds drift south from the
daytime convection. By Thursday these clouds should exit, leaving
mostly sunny conditions with temperatures in the lower 70s for
most inland locations. The thermal trough will remain draped over
the Susitna Valley and Copper River Basin. A shift in flow will
keep much of the convection over the mountains. Thus, overall it
looks like a pretty dry day across the region.

&&

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

High pressure and warm conditions will continue today and
Thursday over Southwest. Daytime highs will reach the low 70s in
low lying areas today. Showers and isolated thunderstorms are
possible this evening, and the best instability looks to be in
the greater Bristol Bay area up into the Alaska Range and in the
Kilbuck/Ahklun Mountains. Though not overly impressive for the
Kuskokwim Valley, there will be enough instability that
thunderstorms can`t completely be ruled out this evening.

A cooling trend will initiate Thursday, as a low over the
Aleutians shifts eastward, switching the general flow pattern to
southerly. Daytime highs Thursday will be several degrees cooler
than Wednesday in the Bristol Bay area; farther north the
difference will be less distinct. Along those lines, there will
again be some potential for evening thunderstorms in the Kuskokwim
Valley Thursday evening. Also of note, expect some gusty gap
winds Thursday into Friday northeast of Kamishak Bay.

Southwest will see a more marked downward trend in temperatures
Thursday into Friday as the region becomes further entrenched in
southerly flow. While this doesn`t look like an overly wet
pattern, expect mostly cloudy or overcast skies Friday.

&&

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

A weakening low roughly 300 miles south of Adak will continue its
slow trek eastward, continuing to fill. Rain and east flow will
continue along the associated front. The low will stall south of
the central Aleutians Thursday, bringing small craft advisory
level winds to the eastern Aleutians, AKPEN and Bristol Bay
Friday.

&&

.MARINE (Days 3 through 5)...

Confidence remains relatively high that a weak gale force front
will slide across the eastern Aleutians and western AKPEN friday
into Saturday, bringing easterly winds. Otherwise there are no
notable storms with gales or higher winds across the forecast
domain.

&&

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

The long range forecast starting on Thursday shows active weather
expected across much of southwest and the Aleutian Chain. An area
of low pressure will continue to bring unsettled weather across
the southwest through early next week. Across southcentral,
ridging will build in through the end of the week, with clearing
skies and warm temperatures. Unsettled weather will return
Saturday as a front lifts from the Gulf of Alaska. Coastal
locations will see rain and clouds through the weekend, while
areas in the Copper River Valley, MatSu and Anchorage Bowl will
see a mix of clouds, sun and light showers.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...SB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MM
MARINE/LONG TERM...SS



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