Gale Warning 147, NWS Juneau, AK

439 
FZAK67 PAJK 201153
OFFAJK

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE JUNEAU AK
353 AM AKDT SAT MAY 20 2017

OFFSHORE WATERS FORECAST FOR GULF OF ALASKA EAST OF 144W

WIND FORECASTS REFLECT THE PREDOMINANT SPEED AND DIRECTION
EXPECTED. SEA FORECASTS REPRESENT THE AVERAGE OF THE HIGHEST
ONE-THIRD OF THE COMBINED WINDWAVE AND SWELL HEIGHT.

PKZ398-210600-
353 AM AKDT SAT MAY 20 2017
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A DEVELOPING GALE FORCE LOW WILL MOVE INTO THE CENTRAL GULF
SATURDAY. THIS WILL PUSH A STRONG FRONT NE OVER THE EASTERN 
GULF BY SATURDAY AFTERNOON, THEN PUSH SLOWLY TO THE OUTER COAST
OF SE AK ON SUN.  

$$

PKZ310-210600-
GULF OF ALASKA NORTH OF 55 DEGREES NORTH AND EAST OF 144 DEGREES
WEST-
353 AM AKDT SAT MAY 20 2017

...GALE WARNING TODAY...

.TODAY...SE WIND 20 KT INCREASING TO 35 KT. SEAS 7 FT BUILDING TO
10 FT IN THE AFTERNOON. RAIN EARLY IN THE MORNING. 
.TONIGHT...S WIND 25 KT. SEAS 10 FT. W SWELL. 
.SUN...S WIND 20 KT. SEAS 10 FT. S SWELL. 
.SUN NIGHT...S WIND 20 KT. SEAS 11 FT. S SWELL. RAIN.
.MON...SE WIND 20 KT. SEAS 10 FT. 
.TUE...WIND VARIABLE LESS THAN 15 KT. SEAS 6 FT. 
.WED...NW WIND 15 KT. SEAS 6 FT. 

$$

307 
FZAK67 PAJK 202309
OFFAJK

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE JUNEAU AK
309 PM AKDT SAT MAY 20 2017

OFFSHORE WATERS FORECAST FOR GULF OF ALASKA EAST OF 144W

WIND FORECASTS REFLECT THE PREDOMINANT SPEED AND DIRECTION
EXPECTED. SEA FORECASTS REPRESENT THE AVERAGE OF THE HIGHEST
ONE-THIRD OF THE COMBINED WINDWAVE AND SWELL HEIGHT.

PKZ398-211715-
309 PM AKDT SAT MAY 20 2017
.SYNOPSIS FOR THE EASTERN GULF OF ALASKA...
A GALE FORCE LOW OVER THE CENTRAL GULF WILL DRIFT N, WITH
ANOTHER GALE FORCE LOW MOVING N AND MERGING WITH IT OVER THE NW
GULF BY SUN AFTERNOON. THESE LOWS WILL PUSH A STRONG FRONT
SLOWLY TO THE OUTER COAST OF SE AK SUN MORNING, THEN ONSHORE 
THROUGH ALL BUT THE SOUTHERN PANHANDLE BY SUN NIGHT. THE FRONT 
WILL WEAKEN OVER THE SOUTHERN PANHANDLE MON. 

$$

PKZ310-211715-
GULF OF ALASKA NORTH OF 55 DEGREES NORTH AND EAST OF 144 DEGREES
WEST-
309 PM AKDT SAT MAY 20 2017

.TONIGHT...S WIND 25 KT. SEAS 10 FT. RAIN LATE. 
.SUN...S WIND 30 KT. SEAS 11 FT. RAIN IN THE MORNING. 
.SUN NIGHT...SW WIND 25 KT DIMINISHING TO 15 KT LATE. SEAS
11 FT. S SWELL. 
.MON...WIND VARIABLE LESS THAN 15 KT. SEAS 9 FT. S SWELL. 
.MON NIGHT...WIND VARIABLE LESS THAN 15 KT. SEAS 8 FT. S
SWELL. 
.TUE...W WIND 20 KT. SEAS 8 FT. 
.WED...NW WIND 15 KT. SEAS 6 FT. 
.THU...WIND VARIABLE LESS THAN 15 KT. SEAS 6 FT OR LESS. 

$$

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
229 PM AKDT Fri May 19 2017

.SHORT TERM.../Through Sat night/A weak occluded front over the NE
gulf will move onshore and dissipate by Sat morning. A much
stronger front will move NE into the eastern gulf Sat afternoon,
then move slowly closer to the outer coast Sat night. A low will
move N into the S-central gulf Sat, then drift slowly NW toward
the NW gulf Sat night. Used blend of the 12z NAM and ECMWF to
handle the low and stronger front. Thought the GFS was a bit too
weak with the low.

Main forecast concerns will be precip potential/amounts and
winds. Will keep some showers going especially over the NW half of
the panhandle tonight as weak front moves in, but they will slowly
decrease as the front eventually dissipates Sat morning. Rain will
move rapidly NNE into the area later Sat morning and afternoon
ahead of the next front. A strong low level jet and anomalously
high precip water with this system will increase rainfall rates
Sat night, and most places will see rain become heavy at times.
Rainfall through Sat night will likely exceed 1 inch in many
areas, especially along S slopes.

Wind will drop off slowly tonight over the area as weak front
moves in and dissipates. Strongest winds early on will be over the
far N panhandle with around 20 KT S winds to start, with 10-15 KT
over much of the remaining area. After the lull in winds late
tonight and early Sat morning, the wind over the gulf and S 2/3rds
of the inner channels will pick up again, with gales likely over
the E gulf and 20-30 KT winds over the S 2/3rds of the inner
channels. The far N channels may see winds become N in the
afternoon but would expect them to be 15 KT or less during that
time. Eventually even the N third will see more wind arrive Sat
night as front moves closer to the area, but these winds will be
more S-SE around 15-20 KT.

.LONG TERM.../Sunday through Thursday/As of 930pm Thursday...The
extended forecast with a warm frontal low pressure system
affecting Southeast Alaska. While there will be some small craft
level winds over the gulf the main impact with this storm
continues to be the rainfall. QPF values are in between 1 and 4
inches across much of the panhandle for the 48 hours encompassing
Sunday and Monday. Currently there is model disagreement within
the total QPF values associated with this system with the GFS
trending the wettest. The precipitation with this system
continues into late Tuesday night and possibly even early
Wednesday. However, it does finally lift eastward out of the
panhandle as a high pressure builds over the gulf during the
middle of next week. Currently there is still model disagreement
handling the end of the precipitation with the GFS continuing to
dry the southern panhandle out Monday while the ECMWF keeps the
entire panhandle wet through Tuesday. Models are in agreement that
rainy conditions continue over the northern panhandle through
most of Tuesday.

This high pressure will lead to much more seasonable and drier
conditions Wednesday into Thursday. With this changing weather
pattern temperatures should warm significantly. 850 mb
temperatures on Thursday are ranging from 10 to 15 C over the
panhandle which lead to an increase in forecast temperatures
toward the end of the extended forecast.

Model agreement is still average with the handling of the low
pressure system at the beginning of the extended forecast with
total rainfall amounts and locations varying widely. Models are in
much better agreement with the high pressure building over the
gulf toward the middle of next week. Used a blend of the ECMWF and
GFS to handle the low pressure system and then a blend of GFS and
WPC to handle the high pressure that builds behind it.

&&

.HYDROLOGY...There is increased concern for the smaller streams
and rivers over the area especially in the central panhandle.
Latest RFC guidance pushes some of the smaller streams into the
bankfull category by Sun night. Later shifts will need to monitor
this situation. Will update the SPS about the heavy rainfall.

&&

.AVIATION...Fairly quiet aviation weather into tonight with VFR
and MVFR ceiling and vis in the north due to showers while the
south maintains VFR conditions. That begins to change into Sat as
the next front comes inland. SE Winds will be increasing by
afternoon from Cape Fairweather southward with LLWS (around 30 to
40 kt at 2000 ft) developing in the southern 2/3rds of the
panhandle particularly in PAKT, PAKW, and PASI. Rain will also be
starting Sat becoming heavy at times by late afternoon and
evening. Vis and ceiling expected to begin to drop into MVFR and
maybe even IFR conditions at times as the rain becomes heavier.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Gale Warning for PKZ041>043.
     Small Craft Advisory for PKZ021-022-031>036-051-052.

&&

RWT/Byrd

Visit us at http://www.weather.gov/Juneau

Special Weather Statement
National Weather Service Juneau AK
229 PM AKDT Fri May 19 2017

AKZ017>029-210000-
Cape Fairweather to Cape Suckling Coastal Area-
Taiya Inlet and Klondike Highway-Haines Borough and Lynn Canal-
Glacier Bay-Eastern Chichagof Island-
Salisbury Sound to Cape Fairweather Coastal Area-
Cape Decision to Salisbury Sound Coastal Area-
Eastern Baranof Island and Southern Admiralty Island-
Juneau Borough and Northern Admiralty Island-
Inner Channels from Kupreanof Island to Etolin Island-
Dixon Entrance to Cape Decision Coastal Area-
Southern Inner Channels-Misty Fjords-
Including the cities of Yakutat, Skagway, Haines, Gustavus,
Hoonah, Elfin Cove, Pelican, Sitka, Port Alexander, Angoon,
Juneau, Petersburg, Wrangell, Kake, Craig, Klawock, Ketchikan,
Metlakatla, and Hyder
229 PM AKDT Fri May 19 2017

...Heavy rain likely this weekend into early next week...

A strong frontal system will move into the Gulf of Alaska this
weekend and remain there through Monday. This front will bring
widespread rain, which may be heavy at times Saturday night
through Monday. Rainfall amounts of 2 to 4 inches are likely with
locally higher amounts possible. It now appears that the heaviest
rain will fall along the central outer coast and central
panhandle. This rainfall will cause rises on area rivers and
streams, and it is possible some smaller streams and rivers may
reach at least bankfull level by Sunday night. Stay tuned to
later forecasts and possible statements for updates on this
developing situation.