487
FXAK68 PAFC 180100
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
500 PM AKDT Mon Jun 17 2024

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

While the low marine stratus has retreated to the coast in many
locations, it is expected to return by Tuesday morning with
coastal communities along the Gulf Coast getting inundated by late
this evening. Some communities such as Cordova will likely remain
socked in by the low clouds through tonight. Communities along
Cook Inlet will see a similar on-again/off-again trend, however
Anchorage may remain clear due to a brief period of southeasterly
flow from Turnagain Arm keeping the stratus at bay. However,
confidence regarding this progression is middling due to
differing flows at very low levels, so stay tuned as expectations
may change.

Interior Southcentral likely to see the clear pattern persist
Tuesday, however following Tuesday, the pattern will begin to
slowly shift and become cooler due to increasing stratiform cloud
cover moving in from the southern Gulf of Alaska. Kodiak will be
entering a cooler pattern as well, however potentially wetter by
midweek and beyond. The trough moving into the Gulf of Alaska is
bringing with it a core of moisture and cooler air, the cause of
the pattern shift across Southcentral. However, models agreement
and consistency regarding the northward progression of this system
is poor. The latest trend is that the system will not progress as
far north, limiting the precipitation impact for Kodiak, will
maintaining the cooler and cloudier pattern, before initiating
more consistent rainfall by Wednesday. This system is driving the
pattern shift across Southcentral, so stay tuned as more elements
regarding its progression come more into line.

&&


.SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING
SEA AND THE ALEUTIANS (Days 1 through 3: TODAY THROUGH WEDNESDAY
NIGHT)...

A potent shortwave moving around the periphery of a weak,
elongated low stationed along the Aleutian Chain has advanced
northwest, initiating numerous thunderstorms already this
afternoon, across the Western Alaska Range, Kuskokwim
Valley and Kuskokwim Delta where a Red Flag Warning is in effect
until 10PM. Several hundred lightning strikes have already been
noted. This level of activity isn`t normally noted across this
area, but is accented by strong vorticity aloft, steep lapse rates
and deep mixing heights, skinny CAPE soundings and enough shear
within the atmospheric column to allow prolonged thunderstorm
life-cycles, capable of producing small hail and ample lightning
across the areas noted above.

This shortwave will advance north over the course of the afternoon
and evening, finally diminishing in energy and getting absorbed
into the upper level flow by morning. Behind it, a quieter,
slightly cooler and more stable air mass will be ushered in,
bringing a period of calm (and light rain showers) through
midweek.

To the south and west across the Aleutian Chain and Pribs, periods
of rain will continue under a south to southeasterly flow as the
elongated low tightens and moves north into the Southern Bering
Sea. The persistent southerly to southeasterly winds will result
in gap wind gusts ranging from 15 to 25 kts through Wednesday
across the Eastern Aleutians and AKPen.

-AB


&&


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

Model agreement is pretty good until around Sunday and the GFS
becomes the outlier. For Friday, mainland Alaska will be separated
by low pressure over the Gulf and high pressure to the north. Any
easterly waves coupled with instability over the mainland could
lead to chances for convection. A progressive ridge over the
Bering Sea will be moving towards Southwest Alaska where low
stratus and fog will be possible. Farther west is a North Pacific
low with a front transecting the Western Aleutians. Precipitation
will accompany primarily small craft winds are expected. Gusts
could approach gales, but are not expected at this time. By
Saturday, the ridge will have moved across mainland Alaska and
overall flow appears weaker, but the slight chances for showers
will linger, especially over higher terrain and thunderstorms
appear less likely for the weekend. Sunnier and drier weather is
possible for the upcoming weekend though. Over the Aleutians, the
low will move along the Aleutian Chain with the front reaching the
Pribilof and the Eastern Aleutians. Model agreement falls apart
later Sunday through Monday. GFS is highlighting a vigorous low
into the Bering Sea, though the representative forecast is leaning
towards a more mild weather with weak lows and more progressive
flow that is similar to what has been occurring more recently.

&&

.AVIATION...

PANC...Stratus with IFR to LIFR conditions continue to linger over
much of Cook Inlet today. The mean flow in the first few
thousands of feet of the atmosphere had a bit of a southeast
component in the vicinity of Anchorage. However, this flow will
back toward the southwest this afternoon through tonight, leading
to increasing likelihood of fog and/or stratus reaching the
terminal sometime tonight or Tuesday morning. For now, have
introduced vicinity fog to indicate that possibility. If
fog/stratus does develop, expect it would clear out during the
day Tuesday due to increasing southeast flow aloft along with
sunshine and warming of the surface.

Winds will remain light.

&&


$$