666
FXAK68 PAFC 061357
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
557 AM AKDT Sat Jul 6 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today
through Monday)...

Rain has moved into Southcentral as the upper level trough
continues to dig southeastward bringing moist, southwesterly flow
at all levels of the atmosphere into the region. Enhancing this
trough is a boundary associated with the front that moved through
the region Thursday night and became stationary from Shelikof
Strait northeastward into Prince William Sound and beyond. What is
interesting about this whole pattern is the way this old front
extends into a low well to the south near 48N 155W this morning.
When looking at a loop of GOES 18 satellite imagery, these
features can be seen as well as the way this boundary (the old
front) is being pushed back to the northwest due to the ridge in
the eastern Gulf. This is relevant since the upper low of this
southern system will phase with the upper low in the Bering early
next week and keep rain in the area for a while. The heaviest
rainfall amounts are expected to be from Hatcher Pass
northeast through the Susitna Valley where 1 to 2 inches of rain
are possible through the weekend. The rainfall after this weekend
is not expected to be as heavy as today into tonight, but it does
look to be persistent in an August-like manner.

The surface ridge of high pressure over the eastern Gulf of
Alaska is keeping the strong southerly gap winds blowing again
today. The pressure gradient should finally start to weaken
overnight tonight and these winds should be much abated for Sunday
and Monday.

&&


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

An upper trough sits over the Seward Peninsula this morning with
a shortwave digging through the southern Bering. At the surface, a
cold front extends from the Kuskokwim Mountains to the Central
Aleutians. Shower activity has been relegated largely along and
ahead of the front, which has become mostly stationary over
Southwest Alaska and more progressive across the southern Bering.
Morning satellite shows low stratus and areas of fog across the
Bering. Over the Kuskokwim Delta and western portions of the the
Lower Kuskokwim Valley/ Greater Bristol Bay regions, another day
of mostly dry conditions can be anticipated. Temperatures will
remain cool and in the 50s/low 60s. Shower chances trend upward by
Monday with the passage of another shortwave out of the Bering
Strait and a swath of better associated moisture.

The only other area of interest this morning is the presence of
an occluded low south of Kamchatka. Its front extends
northeastward to just west of the Western Aleutians, finally
connecting with the cold front over the Central Aleutians. This
should limit the cold front`s movement over the Western Aleutians
today. Tomorrow into Monday the low will briefly track into the
western Bering before sliding southward across the Eastern
Aleutians and back into the North Pacific as an open-wave trough.
Scattered showers and small craft wind gusts will accompany the
low`s track.


&&


.LONG TERM FORECAST (Days 4 through 7) Tuesday through Friday...

On the Alaska upper level map, a pair of Arctic lows merges for
Wednesday. The new center loops into the Northern Bering and sets
up the basis for an extensive low covering nearly all of the
Bering by Friday. A closed center Eastern North Pacific low
weakens as it slips through the Gulf of Alaska and merges with the
Bering system by Thursday. An elongated trough continues across
the Gulf through Friday. Weak high pressure remains in place over
the Eastern Interior through the end of the workweek. Overall
model confidence begins good, but changes in the models towards
the end of the period reduce that confidence. The overall pattern
allows for a longer term moisture advection over Southcentral
Alaska, with periods of rain over the area, and the highest
amounts of precipitation in the foothills of the Alaska Range. A
similar situation occurs with the Bering low pushing moisture into
Southwest Alaska, the Alaska Peninsula and portions of the
Aleutians through the end of the forecast period. Brief periods of
heavier rainfall will occur across the Southern parts of the
state as upper level features rotate through the pattern.

- Kutz


.AVIATION...

PANC...Rain and MVFR conditions expected through this evening as
an upper trough moves in from the west. Southeasterly Turnagain
Arm winds will linger this evening before the pressure gradient
relaxes and winds finally wind down early Sunday.


&&
$$