Small Craft Advisory 357, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
419 PM AKDT Tue May 7 2019

.ANALYSIS AND UPPER LEVELS...
A strong and vertically stacked low center moving north along the
Kuskokwim Delta Coast is slowly weakening. However, strong
pressure gradients and rises on the backside of this system
produced very gusty winds from Bristol Bay to the Copper River
Basin. Gusts in excess of 50 mph were observed through gaps in
the Aleutian Range and along Turnagain Arm. The occluded portion
of the front continues to lift north and west across the western
Mainland and the north Gulf Coast/Southcentral. Fairly widespread
rain was evident over the north Gulf with showers, associated
short waves embedded in the broad upper cyclonic flow, elsewhere.
Satellite imagery shows a broad frontal zone extending from the
Gulf to around 35n 160w. This will be the boundary(pathway) the
next wave takes north into the Gulf tonight.

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.MODEL DISCUSSION...
Models are in much better agreement this run especially with the next
rain maker for Southcentral Tonight/Wednesday.

&&

.AVIATION...
PANC...Gusty southeast winds across the airport complex will diminish
late this evening. Steady rain and potential MVFR conditions are
expected after midnight tonight and should continue through the
morning hours Wednesday.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

A re-enforcing front moves up quickly tonight keeping continuous
rain across the northeast gulf coast, Prince William sound and
eastern Kenai. Rain spreads inland after midnight as low level
flow slackens and the next surface low tracks to Price William
Sound. Rain tapers off Wednesday afternoon with showers
continuing through the evening as the Bering low sends upper
level waves around the gulf which then propagate north toward the
Alaska Range.

Much of the Gulf will see a short break in weather on Wednesday
in the wake of the front. There will be a few showers as upper
level waves move through. Surface flow will be relatively light
out of the south. The next front moves into the Gulf early
Thursday morning with the boundary expected to spread rain across
Kodiak Island, the eastern Kenai and northern gulf coast by mid
morning. Gusty gale force winds are expected around the core of
the low that track to the western Gulf late Thursday into Friday.
This low brings brings another chance for rain on Friday across
Southcentral with gusty easterly flow along typical gap locations
as the boundary pulls inland.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Strong east to southeast winds will increase through the morning
as a surface low tracks north from the central Alaska Peninsula to
the Kuskokwim Delta coast. Winds will turn southerly as the low
passes by and continue through the afternoon and evening.
Widespread rain in the morning will turn over to showers in the
afternoon and evening with showers continuing tonight and
Wednesday in the persistent moist southerly flow. Showers will
taper off somewhat late Wednesday night through Thursday morning.
A frontal system approaching from the southeast will spread more
rain across the area Thursday afternoon through Thursday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A surface low crossing the Alaska Peninsula near Port Moller early
this morning with track north across western Bristol Bay to reach
Cape Newenham around noon. The low will continue north along the
Kuskokwim Delta coast this afternoon and evening as it gradually
weakens. A broad upper level trough with an anchoring upper low
center over the eastern Aleutians will persist over much of the
Bering through midweek. Several other upper low centers, including
the one associated with the surface low currently tracking north
will rotate around the periphery of the the broader trough
Tuesday night through Thursday night keeping it in place and
stretched across the Bering. A developing surface low will track
north into the far southwestern Gulf Thursday

&&

.MARINE (Days 3 through 5: Friday through Sunday)...

On Friday morning, the low inland over Southwest Alaska will
continue to produce gale force winds through Bristol Bay, Shelikof
Strait, and the Gulf waters east of Kodiak. The winds will subside
from east to west through Friday night. There is some potential
for a low to impact many of the same areas Saturday night into
Sunday with an additional round of gale force winds in Shelikof
Strait and the waters around Kodiak. However, there is substantial
model disagreement about this system and uncertainty is high.
Elsewhere, there is good confidence that no areas of high winds
or waves will occur through Sunday.

&&

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

The long-term forecast remains a quiet one overall across much of
southern mainland Alaska. Two different features: a low moving to
near Kodiak and/or Bristol Bay on Sunday, and a cold front and
associated low moving across the northern Bering into the
Kuskokwim Delta are both depicted by only one forecast model, and
left out by the others. Thus, there is high uncertainty about
whether they will impact the area at all. The low that moves
through Southwest Alaska Friday will slowly depart during the day
Saturday, taking most of its associated precipitation with it by
Saturday night across Southwest Alaska. Disorganized shower
activity will be common across most of southern mainland Alaska on
Saturday and Sunday, with high pressure and quieter weather likely
taking over for Monday and Tuesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BC
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM
MARINE/LONG TERM...JW