Gale Warning 547, NWS Anchorage, AK

278 
FZAK62 PAFC 281111
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 AM AKDT SAT SEP 28 2013

OFFSHORE WATERS FORECAST FOR THE BERING SEA

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.

PKZ499-290300-
400 AM AKDT SAT SEP 28 2013
.SYNOPSIS FOR CENTRAL BERING SEA...

A 1003 MB LOW NEAR 50N 172E WILL WEAKEN TO 1015 MB AS IT MOVES TO 48N
173W SAT EVENING. A 1007 MB LOW FORMS NEAR 63N 178W SUN EVENING.

$$

PKZ411-290300-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE
400 AM AKDT SAT SEP 28 2013

.TODAY...NE WIND 20 KT EXCEPT VARIABLE 10 KT N OF 56N. SEAS 5 TO 8
FT. 
.TONIGHT...VARIABLE WIND 10 KT BECOMING SW 20 KT AFTER MIDNIGHT. SEAS
5 TO 8 FT. 
.SUN...SW WIND 15 TO 25 KT. SEAS 5 TO 10 FT. 
.SUN NIGHT...SW WIND 25 KT. SEAS 10 FT. 
.MON...SW WIND 30 KT. SEAS 13 FT. 
.TUE...N WIND 30 KT. SEAS 14 FT. 
.WED...W WIND 20 KT. SEAS 8 FT.  

$$

PKZ412-290300-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N
400 AM AKDT SAT SEP 28 2013

.TODAY...NW WIND 15 KT. SEAS 7 FT. 
.TONIGHT...NW WIND 10 KT BECOMING VARIABLE 15 KT AFTER MIDNIGHT. SEAS
5 FT. 
.SUN...SW WIND 15 TO 25 KT. SEAS 5 TO 8 FT. 
.SUN NIGHT AND MON...SW WIND 25 KT. SEAS 9 FT. 
.TUE...NE WIND 25 KT. SEAS 9 FT. 
.WED...N WIND 25 KT. SEAS 9 FT.  

$$

PKZ413-290300-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N
400 AM AKDT SAT SEP 28 2013

.TODAY...NE WIND 10 TO 20 KT. SEAS 5 TO 8 FT. 
.TONIGHT...N WIND 20 KT BECOMING VARIABLE 10 KT AFTER MIDNIGHT. SEAS
5 TO 8 FT. 
.SUN...VARIABLE WIND 10 KT BECOMING SW 15 KT IN THE AFTERNOON.
SEAS 5 FT. 
.SUN NIGHT...SW WIND 25 KT. SEAS 7 FT. 
.MON...SW WIND 25 KT. SEAS 7 FT. 
.TUE...N WIND 30 KT. SEAS 11 FT. 
.WED...NW WIND 30 KT. SEAS 11 FT.  

$$

PKZ414-290300-
BERING SEA OFFSHORE EAST OF 171W
400 AM AKDT SAT SEP 28 2013

.TODAY...NW WIND 15 TO 25 KT. SEAS 6 TO 9 FT. 
.TONIGHT AND SUN...NW WIND 15 TO 25 KT. SEAS 6 TO 9 FT. 
.SUN NIGHT...W WIND 25 KT. SEAS 6 FT. 
.MON...SW WIND 25 KT. SEAS 8 FT. 
.TUE...E WIND 25 KT. SEAS 7 FT. 
.WED...N WIND 30 KT. SEAS 12 FT.  

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT FRI SEP 27 2013

.ANALYSIS AND UPPER LEVELS...A DEEP LOW IS BOTTOMING OUT AROUND
969 MB THIS MORNING JUST EAST OF KODIAK ISLAND. OVER THE PAST
24 TO 36 HOURS THERE HAS BEEN A PROCESS OF TRANSFERRING UPPER LEVEL
SUPPORT FROM THE ORIGINAL LOW TO A RAPIDLY DEVELOPING TRIPLE POINT
LOW JUST DOWNSTREAM...WITH THE ORIGINAL LOW THEN QUICKLY DISSIPATING.

THE SYSTEM HAS NOW BECOME FULLY WRAPPED UP AND NEARLY VERTICALLY
STACKED...SO EXPECT THIS LOW TO REMAIN INTACT AS IT EXITS TO THE
SOUTHEAST. THIS STORM HAS BEEN SUPPORTED BY A VERY IMPRESSIVE
SUBTROPICAL JET RIDING ACROSS THE BERING SEA OVER TOP OF AN
ANOMALOUSLY STRONG NORTH PACIFIC RIDGE AND THEN DIGGING SOUTHEASTWARD
INTO THE NORTHEAST PACIFIC. THE 12Z SOUNDINGS AT SAINT PAUL AND
COLD BAY CAPTURED THE JET SPEEDS WELL THIS MORNING WITH A MAX OF
190KT AND 170KT RESPECTIVELY. CONSEQUENTLY STRONG WINDS ARE ALSO
BEING OBSERVED AT THE SURFACE FROM THE EASTERN ALEUTIANS TO THE
ALASKA PENINSULA. THIS IS A COMBINATION OF UPPER LEVEL WAVES
TRANSITING THE BACK SIDE OF THE UPPER TROUGH LEADING TO SUBSIDENCE
AND MIXING DOWN OF STRONGER WINDS FROM ALOFT...ALONG WITH WEAK COLD
ADVECTION AND SURFACE PRESSURE RISES ON THE BACK SIDE OF THE SURFACE
LOW CENTER. MEANWHILE...GALE TO STORM FORCE WINDS ARE DEVELOPING OVER
THE NORTHERN TO WESTERN GULF AS THE OCCLUSION MOVES SLOWLY TOWARD THE
COAST. WITH THE LOW ABOUT TO HEAD SOUTHEASTWARD TOWARD THE NORTHEAST
PACIFIC THE NORTHWARD PROGRESSION OF THE OCCLUSION WILL COME TO A
HALT BEFORE MUCH LONGER...SO STRONGEST WINDS WILL REMAIN JUST
OFFSHORE OF THE NORTH GULF COAST. CORRESPONDINGLY MOST OF THE RAIN
WITH THIS SYSTEM IS CONFINED TO THE GULF COAST...KODIAK ISLAND...AND
ALASKA PENINSULA.

LOOKING UPSTREAM...A FORMER TROPICAL SYSTEM OVER THE NORTHWEST
PACIFIC IS WEAKENING AS IT TRACKS TOWARD THE WESTERN ALEUTIANS.
THE SATELLITE DERIVED PERCENT OF NORMAL PRECIPITABLE WATER PRODUCT
SHOWS A LARGE AREA OF OVER 200% OF NORMAL VALUES...INDICATING A
VERY JUICY ATMOSPHERE.

.MODEL DISCUSSION...MODELS ALL INITIALIZED WELL AND ARE IN
REASONABLE AGREEMENT WITH LARGE SCALE FEATURES OVER THE NEXT FEW
DAYS. THE PRIMARY FORECAST CHALLENGE WILL BE QUANTIFYING THE IMPACT
OF THE UPPER LEVEL JET AND SHORT-WAVES MOVING THROUGH THE BACK SIDE
OF THE TROUGH ON THE STRENGTH OF SURFACE WINDS ALONG THE ALASKA
PENINSULA AND ACROSS THE WESTERN GULF. ASIDE FROM THIS
CHALLENGE...FORECAST CONFIDENCE IS ABOVE AVERAGE.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...AS THE STORM SYSTEM OVER THE WESTERN GULF
EXITS TO THE NORTHEAST PACIFIC TONIGHT AND SATURDAY WINDS WILL
DIMINISH AND RAIN WILL COME TO AN END ACROSS MUCH OF THE REGION.
THE ONE EXCEPTION IS THE WESTERN GULF (INCLUDING KODIAK ISLAND)
WHICH WILL SEE STRENGTHENING NORTHWESTERLIES AS THE UPPER TROUGH
AND SUBTROPICAL JET SLOWLY SHIFT EASTWARD. ALSO...LOCALIZED GAP
WINDS WILL PERSIST ALONG THE NORTH GULF COAST DUE TO A TIGHT
SURFACE PRESSURE GRADIENT. THERE IS NO UPPER LEVEL SUPPORT FOR
THESE WINDS SO THIS WILL NOT BE A VERY STRONG EVENT.

SOUTHWEST ALASKA...RAIN HAS DIMINISHED ACROSS MOST OF SOUTHWEST
ALASKA THIS MORNING. THE MAIN IMPACT FROM THE GULF LOW IS STRONG
WINDS ALONG THE SOUTHWEST COAST AND ALASKA PENINSULA. THESE WINDS
WILL BEGIN TO DIMINISH THIS AFTERNOON AS THE LOW BEGINS TO MOVE
AWAY FROM THE REGION. ALTHOUGH WINDS WILL DIMINISH FROM CURRENT
LEVELS...GUSTY WINDS WILL PERSIST OVER PORTIONS OF SOUTHWEST ALASKA
THROUGH MONDAY AS ARCTIC AIR SPILLS DOWN THE WEST SIDE OF THE
UPPER TROUGH. WINDS WILL REMAIN PARTICULARLY STRONG ALONG THE
ALASKA PENINSULA...ESPECIALLY WINDS OUT OF BAYS AND PASSES ON THE
SOUTH SIDE. VARIOUS UPPER LEVEL FEATURES MOVING THROUGH COMBINED
WITH THE LOW LEVEL COLD ADVECTION WILL PRODUCE SOME UPS AND DOWNS
IN WIND SPEEDS. AT THIS POINT IT DOESN'T APPEAR THAT TIMING OF THESE
FORCING MECHANISMS LINES UP VERY WELL. AS ONE FEATURE INDICATES
STRONGER WINDS ANOTHER BECOMES LESS FAVORABLE. BASED ON THIS WINDS
SHOULD REMAIN BELOW WARNING LEVELS FROM HERE ON OUT. SOME OF THE
MORE SIGNIFICANT GAPS...SUCH AS NEAR THE KING COVE AIRPORT...MAY
SEE A FEW GUSTS APPROACH WARNING LEVELS. THE GREATER IMPACT WILL
BE FOR MARINE AREAS ON THE SOUTH SIDE OF THE PENINSULA WHICH WILL
SEE PERSISTENT STORM FORCE GUSTS THROUGH AT LEAST SUNDAY NIGHT.

CONDITIONS WILL REMAIN DRY FOR MUCH OF SOUTHWEST ALASKA. THE ONE
NOTABLE EXCEPTION IS ALONG THE ALASKA AND ALEUTIAN RANGES WHERE
UPSLOPE FLOW AND COLD ADVECTION WILL PRODUCE AREAS OF LIGHT
PRECIPITATION...STARTING AS RAIN TONIGHT AND TRANSITIONING TO SNOW
SATURDAY NIGHT. ALONG THE IMMEDIATE COAST THERE MAY ALSO BE A FEW
SHOWERS AS COLD AIR MOVES OVER THE RELATIVELY WARMER WATER.

BERING SEA/ALEUTIANS...THE ALEUTIANS WILL SEE A GLANCING BLOW AS
THE SYSTEM CURRENTLY OVER THE NORTHWEST PACIFIC PASSES JUST SOUTH
OF THE ALEUTIAN CHAIN. AS MENTIONED IN THE ANALYSIS SECTION ABOVE
THE MAIN IMPACT WILL BE HEAVY RAIN AS A VERY WARM AND MOIST TROPICAL
AIR MASS MOVES TO THE WESTERN TO CENTRAL ALEUTIANS THIS AFTERNOON
THROUGH TONIGHT. THE SYSTEM WILL GET SWALLOWED UP BY A BUILDING
UPSTREAM RIDGE LATE SATURDAY AND QUICKLY DISSIPATE OVER THE NORTH
PACIFIC. ELSEWHERE ACROSS THE REGION QUIET CONDITIONS WILL PERSIST
FOR THE NEXT FEW DAYS.

.LONG TERM FORECAST...MEDIUM RANGE MODELS INDICATE A SIGNIFICANT
CHANGE IN THE UPPER LEVELS NEXT WEEK AS AN UPPER LOW DROPS OUT OF
ASIA INTO THE BERING SEA PUSHING THE SUBTROPICAL JET SOUTHWARD INTO
THE NORTH PACIFIC. THIS WILL PROVIDE A LEAST A BRIEF BREAK IN THE
ACTIVE STORM TRACK AND VERY STRONG STORM SYSTEMS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING...150 155.
         GALE WARNING...120 130 132 136 137 138 140 160 165 176 180.
FIRE WEATHER...NONE.

SEB SEP 13