Gale Warning 443, NWS Anchorage, AK

891 
FZAK61 PAFC 222315
OFFAER

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
315 PM AKDT FRI JUL 22 2016

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.

PKZ399-231330-
315 PM AKDT FRI JUL 22 2016
.SYNOPSIS FOR THE WESTERN GULF OF ALASKA...

A WEATHER FRONT PUSHES ACROSS THE GULF OF ALASKA AND SOUTHCENTRAL
ALASKA THROUGH SAT MORNING. A 998 MB LOW DEVELOPS AT 58N 148W FRI
NIGHT AND MOVES TO 58N 137W BY SUN MORNING AT 1006 MB AND THEN
DISSIPATES. A 1000 MB LOW FORMS NEAR 60N 148W SAT NIGHT AND
DISSIPATES BY SUN AFTERNOON.

$$

PKZ351-231330-
GULF OF ALASKA OFFSHORE NORTH OF 57N AND WEST OF 144W-
315 PM AKDT FRI JUL 22 2016

.TONIGHT...SW WIND 10 TO 20 KT BECOMING W 15 TO 30 KT AFTER
MIDNIGHT. SEAS 5 TO 10 FT. WIDESPREAD RAIN SHOWERS.
.SAT...NW WIND 15 TO 30 KT. SEAS 7 TO 11 FT. RAIN SHOWERS.
.SAT NIGHT...W WIND 15 TO 25 KT. SEAS 9 FT.
.SUN...SW WIND 20 KT. SEAS 7 FT.
.SUN NIGHT...S WIND 20 KT. SEAS 6 TO 9 FT.
.MON THROUGH WED...S WIND 20 KT. SEAS 5 TO 9 FT.

$$

PKZ352-231330-
GULF OF ALASKA OFFSHORE SOUTH OF 57N NORTH OF 55N AND WEST OF
144W-
315 PM AKDT FRI JUL 22 2016

.TONIGHT...W WIND 20 TO 30 KT. SEAS 8 TO 11 FT.
.SAT...W WIND 30 KT. SEAS 10 TO 13 FT.
.SAT NIGHT...W WIND 25 KT. SEAS 10 FT.
.SUN...SW WIND 20 KT. SEAS 7 TO 10 FT.
.SUN NIGHT...SW WIND 20 KT. SEAS 6 TO 9 FT.
.MON THROUGH WED...S WIND 10 TO 20 KT. SEAS 5 TO 9 FT.

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
421 PM AKDT THU JUL 21 2016

.ANALYSIS AND UPPER LEVELS...
Over southern mainland Alaska, the subtropical ridge that has
controlled our weather continues to flatten and get pushed
westward. The upper level ridge axis is currently along the
southwest coast. The jet traversing the ridge is bringing pieces
of energy across the southern mainland...causing the light rain
showers we have been seeing. Most areas of Southwest Alaska
picked up between a quarter and a half inch of rain, while over
Southcentral, this morning's rain dropped one to two tenths of
an inch of rain, helping quell some of the smoke concerns in
Anchorage from the McHugh Creek fire.

The other major weather feature of note is the vertically stacked
low that has been largely stalled over the northwestern Bering.
As of now it's only producing an area of stronger winds to the
south of the circulation center. A subtropical plume of moisture
showing up very well on satellite moving through much of the
southern Bering is causing 30-35 kt sustained winds along the
central and eastern Aleutians. The merger of these features will
be the primary weather makers for the southern mainland over the
next 24-48 hours.

&&

.MODEL DISCUSSION...
Models have come into better synoptic agreement compared to
Wednesday's runs. This is lending to increased forecast
confidence. They did struggle early today with the shortwave
ridging in the wake of the overnight front. Most of them depicted
a sharper ridge keeping things dry across the Cook Inlet Region,
but as it turns out, there was enough energy embedded in the
westerly flow to get 0.13" of rain at Anchorage International.
For the next system, they all now show a more northern track
with the surface low passing over the Kenai Peninsula by late
Fri Night/early Sat Morning. This should set the stage for
widespread rainfall across the southern half of the state,
especially from Cook Inlet through Bristol Bay. There are still
a few minor differences in timing and intensity of the rain and
the potential for some southeasterly gap winds. The higher
resolution models do show a slight increase in the southeast to
northwest pressure gradient through about 12z Fri morning as the
low approaches. These models were favored in handling winds with
this forecast package. The start time of the rain could prove
tricky as most models show precipitation starting around 18z Fri.
However, there looks to be a convective element with this event
which often times leads to erroneous QPF fields. This can also
make some minor differences in the amount of rain. We have
generally trended near the model average or slightly higher.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
As the low slides southeast into the Gulf it will bring significant
rainfall to Southcentral. A few showers this evening will change
into steady rain by midnight from the Susitna Valley to the Kenai
Peninsula. This rain will continue in those areas and also spread
east along the coast and into the Copper River basin. Heaviest
rainfall will be on Fri and not begin to taper off until midday
Saturday over Anchorage and the Kenai, and continue the rest of
the day over the eastern portion of the forecast area. Heaviest
rainfall will be focused over mountain ranges including the
Talkeetna, Kenai, Chugach, and the Wrangell Mountains.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Light rain behind the front will continue off and on into the
early evening as westerly flow continues to stream moisture
onshore. The next frontal wave will reach the Alaska Peninsula
and Southwest Alaska coast this evening, and spread more steady
rainfall eastward through Friday morning. The supporting upper
level trough will swing inland on Friday changing rain over to
showers which will stay abundant through the day, then taper off
from northwest to southeast Friday night. However, upslope flow
will keep steadier rainfall along the mountains through Saturday
morning. The next frontal system will dive out of the northwest on
Saturday and Saturday night bringing additional rain to Southwest
Alaska.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The fast moving surface low tracking through the Central/Eastern
Bering tonight will continue to weaken as it tracks eastward,
before pushing inland by Friday morning. A surface low associated
with a developing frontal wave will cross the central Aleutians
this morning then track east towards Bristol Bay this afternoon
through tonight. Once both these systems swing onshore on Friday,
flat ridging will build over the Bering putting the area into
west-northwesterly flow which will persist into the weekend.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The upper levels have a northerly 90 knot jet streak over the
Kamchatka Peninsula before strengthening into a 120 knot
northerly jet streak over the Western ALeutians by Monday. This
synoptic feature continues to dig into the base of the longwave
trough located south of the Central Aleutians. By Tuesday this
jet streak transitions to a 110 knot southwesterly jet streak
south of the Eastern ALeutians extending into the Gulf of Alaska.
This pattern will result in an upper level closed low over the
Seward Peninsula that will drop down into the Southwest region
while, a secondary deeper closed low develops just south of
Unalaska by Monday evening. These two features phase into one
closed low by wednesday morning located just south of the Eastern
Aleutians. This will result in a deep southwesterly flow in the
North Pacific ocean as it streams towards the Gulf. Therefore,
look for a wetter pattern for the Southwest/Southcentral Alaska
regions as shortwaves track through the Southwest before swinging
around the base of the longwave trough just south of the
Aleutians. These troughs will then follow the southwesterly jet
stream into the Southcentral region bringing abundant moisture,
and precipitation accompanied by cooler temperatures heading into
the midweek time-frame.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 130 172.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...MO
SOUTHCENTRAL ALASKA...DS
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...PD