228
FXAK68 PAFC 060044
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
444 PM AKDT Fri Jul 5 2024

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

The anticipated round of heavy rainfall across Southcentral is
expected to start tonight and last into early Sunday. An upper
level low is moving southeastward towards northern Alaska and will
merge with an Arctic low by the end of the forecast period. As it
does so, a convergence boundary will begin to form in southern
ALaska as it interacts with the existing ridge in the Gulf. This,
along with persistent southwesterly flow will help carry moisture
over most of southern Alaska and produce widespread wetting rains.
In addition, gusty gap winds will continue to persist as a
presure gradient maintains itself over Southcentral.

The heaviest rainfall and gusty winds will begin to diminish
Sunday morning as the upper low begins to be phased out by the
Arctic low in northwest Canada. Southwesterly flow will continue
to persist, allowing for upslope rainfall to continue along the
westward facing mountainsides. Conditions will remain calm through
most of Monday before the next round of widespread precipitation
begins in the late afternoon hours. The Arctic low will shift
southwestward towards northern Alaska, and a new upper low will
enter the western Gulf. Both lows will send shortwaves towards
Southcentral through Monday evening and extending past the short-
term, continuing the trend of unsettled weather well into next
week.

-BS

&&


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

Rain chances return to both Southwest Alaska and the Aleutian
Chain on Saturday. A trough pushing through interior Alaska and a
developing front over the Aleutians are expected to converge with
a westward moving trough over the southern Gulf of Alaska. This
will promote showers spanning the Aleutian Chain into the Western
Alaska Range during the morning hours on Saturday. Unsettled
weather should continue through the weekend, with the next
shortwave arriving late Monday.


&&


.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...VFR ceilings below 5,000ft will persist through the
afternoon and evening. Rain develops late tonight with steady
rainfall expected from early Saturday morning through Saturday
evening. MVFR ceilings and visibilities are expected coincident
with the heavier rain. IFR ceilings are also possible between 8
AM and 2 PM Saturday.

Southeasterly Turnagain Arm winds will also persist across the
terminal through Saturday evening. Sustained winds and gusts are
expected to peak between 10 PM tonight and noon Saturday. Gusts up
to 35 mph are possible during this time period.

&&


$$