792
FXAK68 PAFC 121244
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
444 AM AKDT Wed Jun 12 2024

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

A stacked low south of Kodiak Island will slowly move east over
the next few days while high pressure building over the interior
mainland of Alaska. Easterly flow with embedded shortwaves, has
brought precipitation across the area moving east to west and only
a few isolated showers remain this morning. Rainfall chances will
return late morning over the Copper River Basin and spread west
along the Alaska Range to the Susitna Valley. A few hit and miss
showers will remain possible for the Kenai Peninsula, Anchorage,
and the Matanuska Valley. The building ridge over the interior
will push those chances a little more southward as it scatters out
tonight through Thursday. Residual moisture with showers however
will linger for the Copper River Basin and the mountain foothills
of the Central Chugach Range.

Friday, the low will have moved east and upper level flow will
become northerly with higher pressure to the north and west and
lower pressure to the east. The pressure gradient will decrease,
weakening upper level, northerly flow through the weekend. Skies
will become partly to mostly clear, warming temperatures in low
elevations to the upper 60s to mid 70s. An embedded shortwave
looks to dip south through Copper River Basin which could promote
thunderstorms Friday afternoon. There is a possibility for
thunderstorms to develop over the Matanuska and Susitna Valley
Friday evening too, though chances are expected to be more
isolated. Flow is going to weak though, so any thunderstorms that
develop would be slower moving. The shortwave slightly bends
westward for this weekend, increasing the likelihood for
thunderstorm development to spread into the Susitna and Matanuska
Valleys, the south and western portions of the Copper River Basin,
and even in portions of the Anchorage and Kenai Peninsula area.

rux

&&


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

Light rain showers will linger through this morning across the
Kuskokwim Valley and Bristol Bay and will taper off into this
afternoon. A benign pattern sets up over Southwest for the rest of
the week as high pressure ridging moves in. By Friday, the
chances of convective activity return to the Western Alaska Range. A
low developing west of the Western Aleutians will push south of
the Aleutian Chain through late week, eventually stalling in the
North Pacific south of Adak. This will bring rounds of rain
showers and small craft winds to the Western/Central Aleutians
through the end of the week.


&&


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

High pressure looks to persist across the eastern Bering, the
Alaska Peninsula, and western mainland through most of the long-
term period. However, as with cases in the past, the GFS wants to
break the ridge down too quick on Sunday while the other guidance
has the ridge persisting. Therefore, the GFS seems to be an
outlier at this point. Additionally, the ensembles of the GFS also
have a similar solution to the deterministic GFS while the
ensembles of the other deterministic guidance do indeed have the
ridge persisting. All-in-all, odds favor warmer and drier weather
over southwest through the long-term with the occasional easterly
wave moving through to help induce diurnal scattered showers. Odds
favor cooler and unsettled weather over most of the Aleutian Chain
with low pressure dominating in the North Pacific.

The high pressure over the western mainland looks to nudge
eastward through Sunday and provide mostly dry and warm weather to
Southcentral for that time. Diurnal showers will be possible for
the interior locations of Southcentral and perhaps even
thunderstorms if enough instability builds with day-time heating.
Confidence then decreases dramatically for the Sunday night
through Tuesday timeframe as guidance has different solutions on
the orientation of the ridge and how fast or slow the ridge might
break down. Thus, forecast uncertainty remains on the high side
for Southcentral during the second half of the long-term.

&&

.AVIATION...

PANC...Expect generally light southerly flow and dry conditions.
VFR ceilings will tend to remain greater than 5000 ft this
afternoon, though light showers are possible through the TAF
period which may briefly lower ceilings to MVFR. Rain showers are
most likely this afternoon and evening. Rain chances decrease
heading into Thursday.

Quesada

&&


$$