Small Craft Advisory 361, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
433 AM AKDT Fri May 5 2017

.ANALYSIS AND UPPER LEVELS...
The upper low responsible for active weather of the last few days
is weakening fast in the Gulf. Only a few showers over the water
left from the previously formidable beast. The mainland has lost
most of it's cloud cover from this system; combined with weak wind
at the surface, temperatures are plummeting in protected areas.
Many places have dipped below freezing with another couple hours
of cooling remaining.

The more active area is over the Bering Sea/north Pacific where
a complex low spins just south of Atka. The gale-force front
associated with this system stretches from Adak through the
Pribilof Islands and southeastward near Unalaska. The system has
multiple centers and a 100+ kt jet on the southeastern flank.
While the cloud shield with this system is rapidly covering the
Bering Sea it is not quite to the mainland yet. However, a
hodgepodge of marine stratus and post-convective stratocumulus
affect the mainland.

&&

.MODEL DISCUSSION...
The big uncertainty in the models at this point is the developing
frontal wave as the front nears Kodiak Island later today. The
discrepancy arises from a jet streak/disturbance combo riding the
front as the parent system occludes. Models are torn between
pushing the low/front further north in the Gulf or wrapping it
back around toward the parent low. Most models have trended
toward the latter with the GFS leading the way on that solution.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
After a chilly start to the morning, temperatures will recover
nicely this afternoon under mostly sunny skies as a ridge of
high pressure builds in from the southwest. A weak upper trough
crossing the Copper River Basin will produce a few clouds and
showers along the Wrangell Mountains and Alaska Range. Winds will
generally be light with the exception of some healthy sea breezes,
which will lead to marginally cooler temperatures along the
coastline.

Meanwhile, a front along the Alaska Peninsula this morning will
make its way to Kodiak Island tonight, bringing increasing winds
and steady rain. This front will stall right near Kodiak Island
on Saturday. A low will then form along the front and head right
for Kodiak, leading to stronger winds and heavier rain.

The northern edge of rain will reach the southern Kenai Peninsula
Saturday. Areas to the north will see increasing mid to high
clouds, but will remain dry. Strengthening pressure gradients out
ahead of the front will lead to the return of gap winds Saturday
afternoon and evening along Turnagain Arm, the Knik River Valley,
and the Copper River.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
East to southeasterly winds will increase today as a frontal
system approaches Bristol Bay and then moves inland over the
Kuskokwim Delta and Greater Bristol Bay area tonight. Winds will
be strongest along the Western Capes, Alaska Peninsula and
through the gaps and passes in the Aleutian Range. The frontal
system will weaken and shear apart on Saturday. A developing
frontal wave in the western Gulf will spread additional
precipitation and a reintensification of easterly winds across
Southwest Alaska Saturday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The large vertically stacked low will remain just south of the
Aleutians with its two surface lows rotating around each other as
the entire feature drifts slowly east through Saturday. A third
surface low will develop as a triple point feature along the front
in the western Gulf Saturday. This new low will track back to the
northwest and over the Alaska Peninsula Saturday night as it is
pulled back towards the main center of the upper low.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Next week will be characterized by high pressure that will build
in over the Bering and try to stretch into mainland Alaska. This
ridging will help to push off the low that will be in the Gulf of
Alaska, but it will not be quite strong enough to inhibit
afternoon convection for much of the southern mainland. Mid week
another low will move in over the Aleutians from the south while
the ridging moves more prominently over the mainland.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 130 131 138 150 155 160 165 170 171 175 177
					  178 179 180.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MTL
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JR
LONG TERM...DK