565
FXAK68 PAFC 191331
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
531 AM AKDT Fri Jul 19 2024

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

Discussion:

Showers have tapered off overnight for the Anchorage Bowl and
northwest Kenai Peninsula. Kenai south to the southern tip of the
peninsula saw a few light showers but missed the bulk of the
precipitation...and not expecting much more but an isolated shower
or two for them this morning. Kodiak has also not seen that much in
the way of precipitation and with the southward moving upper low
quickly losing strength, not expecting much in the way of rainfall
accumulations for them either but Kodiak could see scattered showers
linger through much of the day today. The eastern Kenai Peninsula
will also see decreasing showers this morning.

A warmer and drier pattern will then set up for much of inland
Southcentral today and continuing through the weekend. A North
Pacific low will pivot northward Saturday and model consensus has it
parked over the North Pacific nudging into the southern Gulf through
midweek next week before being ushered eastwards as ridging looks to
build over the Gulf. Several vorticity maximums will rotate around
the North Pacific low during this time; however, latest model runs
have shifted Saturday`s wave further south over the far northern
Gulf. The Gulf coast and eastern Kenai are still favored to get rain
moving in with this wave with inland areas remaining generally dry.
This type set-up with easterly waves typically results in a better
environment for convection over the Copper River Basin and Talkeetna
Mountains, but with the shift southwards...might only see some
isolated convection on Saturday and the potential for a slightly
better set-up on Sunday with a more northerly wave pushing through.

- PP

&&


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

The axis of a high pressure ridge is located over the eastern
Bering Sea this morning. Areas of fog was observed overnight at
Shemya and where high pressure is prominent, including the
Pribilofs, east to Mekoryuk and the Kuskokwim Delta. Low ceilings
and visibility is expected across a large portion of the Bering
Sea. An occluded low is centered over the western Aleutians with
its triple point located over the central Aleutians near Atka.
Plenty of moisture is on tap from the subtropics that is expected
to spread across the Aleutians and into the Bering Sea over the
next few days.

Precipitation is moving through the central Aleutians this
morning and the western Bering Sea, but by this evening,
precipitation will lift into the northern Bering and spread east
to the Pribilofs and the eastern Aleutians. There are slight model
difference with the timing of the front, but precipitation should
remain steady, though moderate to heavy at times for a line from
the Pribilofs through Unalaska by Saturday morning. The parent low
will trail behind the front, keeping chances over the Western
Aleutians for the next couple days and then bringing another round
of precipitation for the Central Aleutians Sunday. The low will
slowly meander to the Southern Bering Sea and its front will slow
down considerably as it continues across the eastern Bering Sea
and the Alaska Peninsula. The slow down of the front and the
location of the triple point occlusion directed over the Pribilof
Islands will lead to storm total rainfall at Saint Paul to be
around an inch between tonight through Sunday afternoon. Elsewhere
along the Aleutians could expect roughly half inch to an inch
storm total rainfall. Winds along the front are expected to be
between 15 to 25 mph with gusts to about 30 to 40 mph.

Across Southwest Alaska, skies will gradually clear for this
weekend as the ridge moves east. Showers will be possible each
afternoon through this weekend from southern Bristol Bay to the
foothills of the western Alaska Range and embedded easterly
shortwaves round the periphery of the a Gulf low. Winds are
expected to be light across Southwest and as upper level flow
weakens, convective potential will increase each day. Isolated
thunderstorms will be possible Sunday afternoon and become more
scattered for the following afternoon.

rux

&&


.LONG TERM FORECAST (Days 4 through 7: Monday through
Thursday)...

An omega pattern will dominate the long-term period, with large
upper-level lows situated in the Bering Sea and the North Pacific
near the Gulf. Between these lows, a high pressure ridge will
situate itself over Southwest Alaska. This setup will keep the
Bering Sea, Aleutian Chain, and southern Alaska Peninsula active
due to numerous shortwaves rotating around the Bering low. The
ridge, initially over Southwest Alaska Saturday and early Sunday,
will shift eastward toward Southcentral Alaska while weakening. A
frontal system will be approaching Southwest Alaska by Monday
morning, with locally heavy rainfall possible. Confidence remains
relatively low in the front`s ability to bring precipitation
inland, but the coast is most likely to see rain. Showery and
unsettled conditions are expected across Southwest Alaska through
midweek as more shortwaves pass through the Bering.

For Southcentral Alaska, the North Pacific/Gulf low will pull
easterly waves from the Yukon into the region. This pattern will
be favorable for precipitation in the Copper River Basin and the
Susitna Valley. Through Wednesday, the upper-level ridge will
begin shifting steadily eastward towards the Yukon. This will
allow for surface low pressure and other features to push into the
area, spreading the rainfall expectancy across much on mainland
Southcentral.

&&

.AVIATION...

PANC...Rain showers continue to diminish this morning as an upper
low continues to push southward. Ceilings have risen to VFR this
morning as clouds scour out. Winds will be light through the
period with Turnagain Arm winds expecting to pick up Saturday
afternoon.

&&


$$