Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 150031
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
431 PM AKDT Thu Jun 14 2018

.ANALYSIS AND UPPER LEVELS...

A strong North Pacific low south of the eastern Aleutians is at
its peak intensity and has become vertically stacked. This low
will slowly weaken as it moves into the eastern Bering Sea and
will become the major weather feature for most of southern Alaska
for Friday through early next week.

This afternoon, the precipitation shield associated with this low
remains just south of the central Aleutians and AKPEN, increasing
cloud cover as it moves towards the area. High pressure still
continues over the northern Bering and Southwest mainland,
bringing dry conditions through this evening. The northern Susitna
Valley and northern Copper River Basin will experiencing a few
showers this evening, but the remainder of southern mainland
Alaska should remain dry this afternoon and evening.

&&

.MODEL DISCUSSION...

Models generally seem to be in good agreement with the placement
and intensity of the low that will move over the Aleutians early
Saturday, but there begins to be some differences on the exact
placement of the center once the low moves into the Bering
Saturday afternoon.

&&

.AVIATION...

VFR conditions will persist through Friday morning.
MVFR conditions are possible Friday afternoon as rain moves into
the area. Gusty southeast winds will develop this afternoon and
persist through the night...tapering off as the rain moves in
Friday afternoon.

&&

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

Get out and enjoy the last evening of sunny and warm weather for
much of Southcentral this evening, as there remains very good
confidence that the extra tropical low currently moving into the
Gulf will produce a pattern shift to a much rainier pattern for
most areas by Friday afternoon. The one feature of note before
this occurs is a shortwave dropping down in the interior that has
already produced a few lightning strikes in the Northern Susitna
and Copper River Valleys, which will continue into early this
evening.

The extratropical low will then begin impacting Kodiak Island with
widespread rains Friday morning, which will then quickly spread
into Northern Gulf and Southcentral by the afternoon, producing a
wet Friday evening for most areas. This will even occur as a gale
force barrier jet sets up along the North Gulf Coast, producing
gusty gap winds through Turnagain Arm and the Knik River Valley.
These winds will, however not produce much downsloping drying as
deep/moist southwesterly flow above it will overcome any drying
from the downsloping. The one piece of good news for this weekend
is that the models have now trended much drier for inland
Southcentral (such as the Anchorage Bowl, Western Kenai, and MatSu
Valleys). While widespread sunshine is not expected, it now
appears that the worst of the rainfall should end early Saturday
morning, with just passing showers expected for the remainder of
the weekend. This will be a different story for most of the Gulf
Coast, as deep southerly onshore flow is expected to bring
widespread and persistent rains through the weekend.

&&

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

Models continue to trend a couple of hours slower with the
progression of the North Pacific low as it advances toward the
eastern Aleutians. With that said, the only effect will be a
slight delay in the onset of precipitation for southwest Alaska; we
are still expecting quite a wet and gloomy weekend. Cloud cover
will thicken and lower overnight as an occluded front continues to
track toward the Alaska Peninsula. Rain will develop over the
AKPen late tonight and progress toward Bethel, Aniak, and
Sleetmute by Friday afternoon. Bands of rain will persist through
early Sunday as the surface low stalls in the eastern Bering.
Downsloping south to southeasterly winds aloft may limit rainfall
amounts along the eastern side of the Alaska Range. Rainfall
should come to an end Sunday afternoon over most interior
locations as an upper-level ridge builds over the region.

&&

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

High pressure over the northern Bering will continue to retreat to
the north tonight as a well-developed low pressure system
advances toward the central Aleutians. Easterly winds that
increased to gale-force this afternoon across the Pacific marine
zones of the central and eastern Aleutians will continue through
the overnight hours before diminishing slightly tomorrow.
Widespread precipitation in advance of an occluded front will also
overspread the Aleutians tonight. The low will track near
Unalaska Saturday afternoon and continue northward into the Bering
Saturday evening. The slow movement of the low, along with a
broad, cyclonic flow throughout the Bering, will keep clouds and
precipitation over the region through the weekend.

&&

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

A major shift in the pattern will be well underway by Sunday
evening as a large trough will be in place over the eastern Bering
Sea with a big ridge over the Eastern Pacific. Folks who read this
forecast discussion tend to know what that means: it is gonna be
cloudier and wetter. Sunday night and Monday looks quite wet as a
low moving in from the subtropics brings widespread rain and
possibly some gusty southeast gap winds. Another low looks to move
inland Tue-Wed, but timing is uncertain at this juncture.
Thereafter, the trough weakens but it does look to remain in place
which should keep at least a decent amount of clouds and rain
chances through the end of the week...along with cooler temps.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gales 119 130 131 155 172 174 176.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...EZ/AH
SOUTHCENTRAL ALASKA...DEK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM
LONG TERM...JA


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