Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 120051
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 PM AKDT Tue Jun 11 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. Moreover,
afternoon thunderstorms have once again developed, with the more
active thunderstorms over Southwest Alaska.

&&

.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 through 3/Tuesday
night through Friday)...

The frontal system anticipated to move into the northeastern gulf
coast has arrived as expected. Light rain is currently falling
around Cordova/surrounding area and is starting to work its way
over the Chugach into the Copper River Basin. This front is still
expected to weaken as it rotates inland, so precipitation should
be tapering off to showers tonight and tomorrow.

Outside of making for cool and wet conditions along the coast, the
main impact of this low is pushing the thermal trough and its resultant
convection more over the MatSu Valleys and northern Copper River
Basin this evening and tomorrow. In fact, convection is firing
over the Talkeetna Mountains now. We also have the possibility of
having some thunderstorms fire on the hillside above Anchorage
this evening. After the front dissipates Thursday, we should see
convection return to much of the Copper River Basin again.

&&

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

A persistent pattern has been in place over the region. There is
a upper level ridge that is bisecting southwest Alaska and
thermal troughs have developed in a few of the valleys. A number
of locations in low elevations will reach the 70s each afternoon
this forecast package. On the models, several instability
parameters (including CAPE, Lifted Index, CAPE and Totals Total)
point to additional afternoon/evening convection. Numerous
lightning strikes have already been detected this afternoon over
SW AK. The radars at both Bethel and King Salmon have been active
this afternoon. Thunderstorms will continue to be diurnally driven
over the next few days. By Friday, a front associated with a
North Pacific low will bring cloud coverage and cooler
temperatures to the region.

&&

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

A mature low southwest of Adak will continue its trek eastward.
This system has already peaked out and the models show this low
slowly filling and weakening. Rain and easterly flow can be
expected as the front progresses eastward. The system starts to
slow down Thursday.

&&

.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...SS
SOUTHCENTRAL ALASKA...BB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PJS
MARINE/LONG TERM...SS



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