Gale Warning 392, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
529 AM AKDT Tue Apr 16 2024

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

The upper level ridge that has brought sunny skies, warmer
temperatures, and quiet weather to Southcentral over the past
several days will continue to shift east today before becoming
blocked over northwestern Canada by a broad low sweeping across the
southern Provinces this week. While the warmer temperatures will
stick around a bit longer, even seeing additional warming for much
of Southcentral through the end of the week, a more active weather
pattern will begin to set up today across the northern Pacific and
western Gulf. This pattern will bring increasing rain chances for
Kodiak Island and portions of the eastern Kenai Peninsula for much
of the week. In addition, gale to storm-force winds winds will
develop across the western Gulf and Barren Islands late tonight
through Wednesday.

The system responsible is currently getting its act together this
morning as pushes south across the Bering Sea. The trough will
elongate, reaching into the north Pacific, as it sweep across the
Central Aleutians...with a secondary upper low developing as it
pushes south of the Aleutian Chain late tonight. Several shortwave
troughs on the southern periphery of the longwave trough will lift
north towards Kodiak Island and into Southcentral. The front will
also lift north towards Kodiak Island with is looking to stall near
the Barren Islands midweek before finally pushing north towards the
Gulf coast by late this week. A modest surge of moisture ahead of
this system will allow for efficient precipitation processes
resulting in locally heavy rainfall spreading into Kodiak Island
late this afternoon and evening, and then into the southeastern
Kenai Peninsula by Wednesday. Temperatures may be initially cold
enough at lower elevation on Kodiak to start out as a rain/snow mix
but should quickly warm and change over to all rain. Moderate to
heavy rainfall looks to persist into Thursday, but could see showery
conditions linger into the weekend. Models remain pretty consistent
with rainfall amounts of about 3 to 5 inches along the southeast
side of Kodiak and up to several inches for lower elevations along
for coastal areas for southeast Kenai Peninsula through Thursday.

- PP

&&

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

Current observations throughout Southwest Alaska show wind gusts
ranging from 35 to 45 mph and snow for a few areas in the
Kuskokwim Delta including Bethel, Kongiganak and Cape Newenham.
These strong winds will diminish throughout the day as a low
pressure system south of the Aleutians moves northeastward toward
the Alaska Peninsula. Warm southerly air is expected with a
sustained push of moisture resulting in a mostly rain event
tomorrow afternoon into Thursday evening for Southwest Alaska.
Wind gusts during this time frame in Southwest Alaska ranging from
30 to 40 mph is expected.

As this low moves north and east, snow and northerly winds on its
backside first in the Central Aleutians then eastward to the
Alaska Peninsula will gust up to 55 mph. Northerly winds through
the gaps west of Nikolski will experience these gusts early
tomorrow morning with locations east of Nikolski to Cold Bay
beginning tomorrow afternoon. These winds will remain strong for a
3 to 6 hour period from their onset before the gusts diminish to
as high as 30 mph.

-DJ

&&

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

The long term forecast begins late Thursday with a strong ridge
of high pressure situated over the Yukon and a negatively tilted
longwave trough extending southeast from the central Bering. A
vertically stacked low well south of the Alaska Peninsula Thursday
slowly lifts to the AKPen and eastern Aleutians through Friday. A
front attached to the low looks to remain nearly stationary near
Kodiak Island, allowing moisture to continue to stream toward the
island on southeasterly winds aloft from the eastern Pacific. This
moisture stream will likely result in several additional inches
of rain for parts of Kodiak Island through Saturday before the
front finally weakens and shears apart.

To the north, an inverted trough is the boundary between warmer
air over Southwest Alaska and a colder airmass over the western
half of the Bering and Aleutians. Precipitation will focus along
the trough axis, with rain for Southwest and a mix of rain/snow
to the west of the trough.

By Saturday, the ridge looks to extend across interior Alaska,
suppressing the trough to the south, along the Aleutians and
southern Gulf of Alaska. The ridge will likely lead to generally
quiet conditions for much of interior Alaska, including the
Southern Mainland. The exception would be along the immediate
coast, where a front lifting toward the northern Gulf may bring
some precipitation from Prince William Sound to the AKPen by
Sunday or Monday.

TM

.AVIATION...

PANC...VFR conditions are expected to prevail through the period.
Turnagain Arm winds have slackened this morning, but will re-
strengthen later this morning into the afternoon. Gradients will
favor the jet coming straight out of Turnagain Arm to Fire Island
and the northern Inlet. Still, as the sun warms up the surface,
the terminal will likely see some gusty southeast winds on the
northern periphery of the jet. By this evening, the stronger Turnagain
Arm winds will shift down-inlet with light northerly winds over
the terminal.

&&

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