Gale Warning 301, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
448 PM AKDT Wed Apr 13 2022

.ANALYSIS AND UPPER LEVELS...

The upper level omega block ridge is still in place over mainland
Alaska, though it is showing some signs of weakening slightly as
cirrus is overriding it to a greater extent than yesterday. The
surface portion of this ridge is split with one center in the Gulf
of Alaska and the other (stronger) portion in the Arctic. The Gulf
center can be seen in visible satellite imagery with some marine
stratocumulus clouds rotating clockwise around it. This is also
pushing some southwesterly surface flow up Cook Inlet which could
induce a marine layer push up the Inlet later tonight.
The vertically stacked, occluded low remains in the western
Bering Sea this afternoon. The jet stream is moving just south of
the upper level low center and the new surface low is just
starting to spin up under the left exit region of the jet streak
in the central Aleutians.

&&

.MODEL DISCUSSION...
Models are still in good overall agreement into the weekend with
the main issue remaining near the Pribilof Islands tomorrow. The
GFS and NAM have now both moved the low track just southeast of
the Pribilofs tomorrow afternoon and evening which would increase
the chance of snow there (instead of rain) due to the more
southerly track as compared to yesterday. The ECMWF and Canadian
are keeping a slightly warmer solution for the Pribilofs with the
low tracking just northwest of the Islands which is closer to
yesterday's solution.

&&

.AVIATION...
PANC...VFR conditions and light winds are expected to persist.
There is a chance for low stratus to develop again tomorrow
morning around sunrise.

&&

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

The strong ridge in place over Southcentral will persist for one
more day, bringing generally clear skies and warmer temperatures.
However, as was the case this morning, marine stratus may return
overnight across Anchorage and the western Kenai Peninsula. The
pattern will begin to change by Friday as a front enters the
western Gulf. Rain and gusty southeasterly winds are expected over
Kodiak. Showers will also develop along the Gulf coast ahead of
the front, but will change to a mix or all snow by the evening as
colder air builds in aloft. The front stalls through Saturday and
this general setup will continue trough the day. Gusty
southeasterly winds are likely along Turnagain Arm Friday
afternoon/evening ahead of the front, though will not be overly
significant.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight
through Saturday)...

Fairly good model agreement with the low pressure circulating
over the entire Bering sea. This will continue into the weekend
as a blocking ridge remains steadily over the western Gulf. Rain
showers today near Dillingham and Cape Newenham will gradually
diminish tonight, although a scattered shower will remain possible
through Thursday as southerly flow continues through Southwest
Alaska. As energy from the low circulates around from the southern
Bering Thursday into Friday, the pressure gradient will tighten
across the entire southwest and a jet streak from the southeast
will pass the Bristol Bay area through the Kuskokwim coast late
Thursday night through Friday. Most of the precipitation will be
along the Kuskokwim and Aleutian mountain ranges with
southeasterly flow. Consequently, QPF will be low in areas of
downsloping such as King Salmon and Bethel. Coastal areas could
have a quarter to half inch while higher elevations could see
upwards of one to three inches. High temperatures for these areas
could be in the mid to upper 40s through Saturday afternoon.
Showers diminish Friday night through Saturday, however
southeasterly flow will continue and gusts through the Kamishak
gap will increase during the day Friday before subsiding Saturday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS/ALASKA PENINSULA (Days
1 and 3: Tonight through Saturday)...

A broad area of low pressure over the Bering sea will continue
into the weekend. Fairly good model agreement in the short term. This
low will circulate towards the southern Bering tonight helping to
increase precipitation over the Central Aleutians beginning
tonight. South to southeasterly flow will begin to increase from
Atka to Dutch Harbor after midnight. By Thursday morning,
southeasterly winds will have increased to gales. Winds will peak
near Unalaska on Thursday morning with gusts to at least 55 kts
possible. Winds will continue to increase during the day Thursday
and move east to the Cold Bay area. Similarly gusts will be near
55 kts. On the latest 850 mb wind speeds models during this time
are closer to 60 to 65 kts and with flow perpendicular to the
islands, an isolated higher gust over 60 kts is not out of the
question. Strong winds will reach Bristol Bay and Cape Newenham
during this time and stretch northwest to the Pribilofs as well.
Wind speeds in the 40 to 50 kt range over a broad swath of the
western Bering to the Pribilofs remain likely. Winds may diminish
slightly before another resurgence of westerlies along the
Aleutians will follow behind the front. Precipitation will be
predominantly rain for most, however snow may mix in at times
during this frontal passage Thursday. Cold air behind the front
Friday and Saturday will have more of a widespread rain snow
mixture. The Pribilofs can expect a change over to snow and
perhaps a little over an inch of snow is possible Thursday
morning.

&&
.Marine (Days 3 through 5: Saturday through Monday)...

Gulf of Alaska: High pressure over the Gulf is forecast to break
down somewhat over the weekend as a triple point low encroaches
upon the western Gulf on Saturday. However, it looks as if the
ridge will bend but not break and remain over the eastern Gulf. A
stationary front draped from the Barren Islands southeastward into
the Northwest Pacific will move little through the period,
eventually shifting southwestward on Sunday as high pressure tries
to reclaim some ground over the Gulf. Light and variable winds
can be anticipated over much of the Gulf, though a band of
southeasterly gales flowing across the Barren Islands Saturday
morning will gradually diminish to small craft strength by
Saturday night. Subsequent seas initially around 12 feet will also
subside through early next week.

Bering Sea: A large vertically stacked upper low is forecast to
be in place over the Bering to start the period on Saturday.
Ongoing westerly gales to the north of the West/Central Aleutians
will also diminish as a result with mild conditions anticipated
over the remainder of the Bering. By Sunday a fast moving North
Pacific low is forecast to slide eastward over the Aleutians.
Strong warm air advection associated with the low's movement will
promote an impressive baroclinic zone with enhanced easterly winds
possible along and north of the low's front on Sunday. Cold air
advection behind the low may promote enhanced northerly gales for
much of the western Bering and Central Aleutians on Monday.

&&

.Long Term Discussion (Days 4 through 7: Sunday through
Wednesday)...

An active pattern is forecast over the Bering through the middle
of next week with multiple troughs of low pressure to push across
the Bering through Wednesday. This pattern should promote several
opportunities for shower activity over the Bering with cold air
advection associated with passing lows reinforcing the ambient
cold airmass. Thus, snow will be favored for all but areas
further south where a mix of rain and snow will be possible over
the Aleutians. Across Southwest colder upper level temperatures
are forecast to persist with areas of light snow possible on
Sunday. Though high pressure looks to expand over Southwest early
next week with a break in precipitation chances to develop. The
forecast for Southcentral is a tad simpler with high pressure over
interior Southcentral and the Gulf budging little, which should
keep passing disturbances south of the region for the most part.
Any precipitation chances across Southcentral will likely be
limited to coastal areas and the higher elevations of the
mountains through Wednesday.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 150 155 161 165 170-177 179 180 181 185 413
414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...AP
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
MARINE/LONG TERM...BL