Gale Warning 288, NWS Anchorage, AK

004 
FZAK61 PAFC 211156
OFFAER

Offshore Waters Forecast
National Weather Service Anchorage AK
356 AM AKDT Sun Apr 21 2019

Offshore waters forecast for the Gulf of Alaska West of 144W

Wind forecasts reflect the predominant speed and direction
expected. Sea forecasts represent an average of the highest
one-third of the combined wind wave and swell height.

PKZ399-220045-
356 AM AKDT Sun Apr 21 2019
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...A 989 mb low at 58N 147W
moves inland near 61N 152W at 983 mb Sun afternoon. Its front wraps 
over the North Gulf Coast through Sun afternoon. A 986 mb low near 
51N 145W sweeps into the Yukon Territory at 981 mb by Mon afternoon. 
Several troughs press across the Gulf through Tue morning.

$$

PKZ351-220045-
Gulf of Alaska Offshore North of 57N and West of 144W-
356 AM AKDT Sun Apr 21 2019

..GALE WARNING TODAY>>>

.TODAY...SW wind 10 to 25 kt, except E 35 kt north of 58N early. 
Seas 10 to 13 ft.
.TONIGHT...W wind up to 20 kt increasing to 15 to 25 kt after
midnight. Seas 10 ft.
.MON...SW wind 20 to 30 kt. Seas 8 to 13 ft. Slight chance of
thunderstorms.
.MON NIGHT...SW wind 15 to 25 kt. Seas 10 ft.
.TUE...SW wind up to 20 kt. Seas 6 to 11 ft.
.WED THROUGH THU...NE wind 15 kt. Seas 4 to 7 ft.

$$

PKZ352-220045-
Gulf of Alaska Offshore South of 57N North of 55N and West of
144W-
356 AM AKDT Sun Apr 21 2019

.TODAY...SE to SW wind 15 to 25 kt early becoming W wind up to 20 kt
in the afternoon. Seas 10 ft.
.TONIGHT...W wind 10 to 25 kt increasing to 20 to 30 kt after
midnight. Seas 9 ft.
.MON...W wind 25 kt. Seas 8 to 11 ft. Slight chance of
thunderstorms.
.MON NIGHT...W wind 25 kt. Seas 11 ft.
.TUE THROUGH WED...SW wind up to 20 kt. Seas 6 to 11 ft.
.THU...NW wind up to 15 kt. Seas 5 ft.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
450 AM AKDT Sat Apr 20 2019

.ANALYSIS AND UPPER LEVELS...

A deep trough continues to remains entrenched along an axis that
extends from northwestern Alaska to the Alaska Peninsula. This
trough is anchored by a pair of mid-level lows, with one centered
near Kotzebue, and the other across southwest Alaska. These two
features, along with several smaller scale circulations, have been
rotating around each other in a Fujiwhara-like fashion, which
helps maintain the trough orientation and position.

At the surface, some small scale circulations have been observed
on Doppler Radar imagery this morning, with one being located
south to southeast of Bethel (this was interesting to watch around
09z when the tiny MCV induced a larger mass response in the wind
fields), and another that was observed over the Cook Inlet west of
Kenai, which has since dissolved.

A general showery type pattern is seen in radar imagery across
southwest Alaska, with a greater coverage and intensity noted
across much of Southcentral, especially near the Prince William
Sound Coast. This heavier precipitation has played a role in
reduced visibilities at some area airports.

&&

.MODEL DISCUSSION...

The models remain in excellent agreement at the surface and aloft,
leading to a higher than average forecast. The GFS model is
slightly faster and has a little further west position of a
surface low moving towards the Kenai Peninsula on Sunday. However,
both models are within a millibar or two in strength of each
other, with good pressure field continuity. Thus, impacts to the
forecast are minimal.

&&

.AVIATION...

PANC...Snow showers crossing the terminal will hold ceilings down
to around 2200 feet for a few more hours, before VFR conditions
prevail through the afternoon. However, an area of low pressure
will approach the region later this evening and into Sunday,
dropping both ceilings and visibilities back into the MVFR range,
as widespread precipitation develops.

&&

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

A dynamic pattern will unfold through the weekend. The upper level
low that brought the colder air and snow to close out the work
week remains over the Susitna Valley this morning. Its trailing
shortwave and associated instability continue to produce
widespread showers across much of Southcentral. With the cooler
airmass, most locations are holding as snow during the overnight
hours except for spots right along the immediate coast. This
shortwave should continue to lift north and out of the area
through the day today. A transient ridge will slide through this
afternoon and could even bring some breaks of sunshine back to the
area. The April sun should once again allow high temperatures to
crest into the low 40s for nearly all areas.

Another potent low will take shape over the Gulf of AK heading
through the day. In advance of this system, deep southerly flow
and instability along the coast (mainly Prince William Sound
through Cordova) will keep precipitation falling through the day.
Higher elevations such as Thompson Pass could pick up several more
inches of snow. As the low center itself approaches tonight, it
will shift the corridor of heaviest precipitation slightly to the
west highlighting Western Prince William Sound through Seward. It
will bring several more inches of snow to the higher elevations
(1500' and above) around Turnagain Pass. This system will also
create some gusty south to southeast winds with a fairly tight
pressure gradient. These will stretch up through the typical
locations of the Turnagain Arm, Knik River Valley, and Copper
River Basin. For places along the Western Kenai Peninsula, there
could be a brief period of blowing snow early Sun morning as
down-Inlet flow initially reinforces some colder air. But once
the east- southeast winds push in Sunday, temperatures should rise
quickly and precipitation at sea level will quickly turn over to
rain. Around the Anchorage Bowl, a brief shot of snow is all that
is expected before cross-barrier flow ramps up and dries things
out.

Unsettled weather will remain in the forecast to start next week.
While there doesn't appear to be any large-scale snow events for
the population centers at this time, the airmass will certainly be
cold enough to support snow and keep things feeling like early
March.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3/Today
through Monday night)...

An upper level low will continue to track northward over western
Alaska today. As it phases with a second upper low to the north,
a broad upper trough will form and continue to bring cooler
temperatures, mostly cloudy skies and scattered flurries over
Southwest and mixed precipitation over the AKPEN.

Although some uncertainty still exists, models are coming into a
general consensus for widespread accumulating snow in the Lower
Kuskokwim Valley on Sunday as a strengthening low tracks northward
over the Gulf. The center of the low will move over Cook Inlet by
midday providing a good setup for the development of a
deformation band as the associated moisture tracks over the Alaska
Range. While higher elevations will as usual see the most
accumulation, confidence is moderate to high for at least 2 to 5
inches from Iliamna to Crooked Creek with localized higher amounts
possible by Monday morning. Areas along the Kuskokwim Delta and
Bristol Bay coast should remain generally snow free, however
onshore flurries and gusty winds are likely along the immediate
coastline.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3/Tonight
through Monday night)...

A broad upper level low and associated shortwave troughs will
continue the cool and cloudy pattern experienced over the region
the past several days. Persistent northerly flow will bring
scattered snow showers (possibly mixing in the afternoon) for
much of the Aleutians today. These will become more widespread
Sunday and Monday. Again, mixing will be possible when maximum
temperatures will occur, however precipitation should still
mainly fall as snow.

&&

.MARINE (Days 3 through 5)...

A series of weak lows will move through the region early next
week. Models are in good agreement that these lows will stay below
gale force, however there is a chance for a few isolated areas
that could briefly reach gale force winds in the Gulf.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The long term forecast, beginning Monday night, looks to have a
broad, complex low over the southern mainland. This setup will
keep the region unstable with showers over the area. There is some
inconsistency amongst the models on when the pattern will shift
but the general idea is that the low will push off to the
southeast sometime Wednesday with high pressure moving in. The
result is the showers clearing out for most locations for the
southern mainland. By the end of the week there is high model
disagreement resulting in the ensembles being preferred.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 119 125
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...MSO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AP
MARINE/LONG TERM...DK/MM