Gale Warning 91, NWS Anchorage, AK

375 
FZAK62 PAFC 061201
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 AM AKST SAT FEB 6 2010

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.

PKZ499-070300-
400 AM AKST SAT FEB 6 2010
.SYNOPSIS FOR CENTRAL BERING SEA...

A NORTH TO NORTHEAST FLOW WILL PERSIST OVER THE BERING SEA THROUGH
SUN AFTERNOON. A STRONG WEATHER FRONT WILL AFFECT THE WESTERN
ALEUTIANS SUNDAY EVENING AND SPREAD TO THE CENTRAL AND EASTERN
ALEUTIANS SUNDAY NIGHT. 

$$

PKZ411-070300-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE
400 AM AKST SAT FEB 6 2010

.TODAY...NE WIND 25 KT. SEAS 15 FT. 
.TONIGHT...NE WIND 20 KT. SEAS 11 FT. 
.SUN...E WIND 25 KT. SEAS 7 FT. 
.SUN NIGHT...NE WIND 30 KT. SEAS 11 FT. 
.MON...NE WIND 35 KT. SEAS 13 FT. 
.TUE AND WED...N WIND 30 KT. SEAS 12 FT.  

$$

PKZ412-070300-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N
400 AM AKST SAT FEB 6 2010

...HEAVY FREEZING SPRAY WARNING TODAY...

.TODAY...N WIND 20 KT. SEAS 7 FT. SNOW. HEAVY FREEZING SPRAY. 
.TONIGHT...N WIND 15 KT. SEAS 6 FT. SNOW. FREEZING SPRAY. 
.SUN...E WIND 15 KT. SEAS 5 FT. SNOW SHOWERS. 
.SUN NIGHT...NE WIND 25 KT. SEAS 7 FT. 
.MON...NE WIND 40 KT. SEAS 17 FT. 
.TUE...NE WIND 35 KT. SEAS 14 FT. 
.WED...N WIND 30 KT. SEAS 11 FT.  

$$

PKZ413-070300-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N
400 AM AKST SAT FEB 6 2010

.TODAY...NE WIND 20 KT. SEAS 9 FT. FREEZING SPRAY. 
.TONIGHT...NE WIND 15 KT. SEAS 8 FT. 
.SUN...E WIND 25 KT. SEAS 7 FT. 
.SUN NIGHT...NE WIND 35 KT. SEAS 12 FT. 
.MON...NE WIND 45 KT. SEAS 19 FT. 
.TUE...N WIND 35 KT. SEAS 15 FT. 
.WED...N WIND 30 KT. SEAS 12 FT.  

$$

PKZ414-070300-
BERING SEA OFFSHORE EAST OF 171W
400 AM AKST SAT FEB 6 2010

...HEAVY FREEZING SPRAY WARNING THROUGH TONIGHT...

.TODAY...N WIND 25 KT. SEAS IN ICE FREE WATERS 7 FT. HEAVY FREEZING
SPRAY. 
.TONIGHT...NW WIND 25 KT. SEAS IN ICE FREE WATERS 7 FT. HEAVY
FREEZING SPRAY. 
.SUN...NW WIND 15 KT. SEAS IN ICE FREE WATERS 5 FT. 
.SUN NIGHT...NE WIND 35 KT. SEAS IN ICE FREE WATERS 9 FT. 
.MON...NE WIND 45 KT. SEAS IN ICE FREE WATERS 15 FT. 
.TUE...NE WIND 35 KT. SEAS IN ICE FREE WATERS 11 FT.
.WED...NE WIND 25 KT. SEAS IN ICE FREE WATERS 7 FT.  

$$

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM AKST FRI FEB 5 2010

.ANALYSIS AND UPPER LEVELS...ALL THE PIECES ARE COMING TOGETHER
TODAY FOR DEVELOPMENT OF A MAJOR STORM OVER THE GULF OF ALASKA.
THERE IS A HIGH AMPLITUDE TROUGH WHICH EXTENDS FROM A POLAR
VORTEX OVER THE BEAUFORT SEA SOUTHWARD TO A NEWLY FORMED CLOSED
LOW OVER BRISTOL BAY. COLD ADVECTION ON THE BACK SIDE OF THE
TROUGH IS PRODUCING GUSTY NORTHERLIES OVER SOUTHWEST ALASKA...THE
EASTERN TO CENTRAL BERING...AND THE ALASKA PENINSULA. SNOW SHOWER
PRODUCTION IS IN FULL FORCE JUST OFF THE ICE EDGE AS THE ARCTIC
AIR MOVES OVER THE WARMER WATERS. ON THE DOWNSTREAM SIDE OF THE
TROUGH SOUTHEASTERLY FLOW FROM THE GULF TO SOUTHCENTRAL IS
PRODUCING FAIRLY WIDESPREAD OVERRUNNING SNOW. A LOOK AT THE
12Z ANCHORAGE SOUNDING SHOWS A THICK LAYER OF ARCTIC AIR IN
PLACE WITH A STEEP INVERSION EXTENDING ALL THE WAY UP TO 2500
PLUS FEET...WHERE THE TEMPERATURE WAS AROUND -7 DEGREES CELSIUS.
THE GULF AIR IS BEING FORCED RIGHT OVER THE TOP OF THIS AND PRODUCING
SNOW. OUT WEST...THERE IS A RIDGE OVER THE WESTERN BERING IN BETWEEN
THE MAINLAND ALASKA TROUGH AND ANOTHER HIGH AMPLITUDE TROUGH RUNNING
WEST TO EAST FROM EASTERN ASIA TO JUST SOUTH OF THE ALEUTIANS. AN
OCCLUDED FRONT EXTENDING FROM A SYSTEM SOUTH OF KAMCHATKA IS RIGHT
ALONG THE WESTERN ALEUTIANS PRODUCING MAINLY SNOW. ALSO...THERE IS
A VERY TIGHT PRESSURE GRADIENT FROM THIS FRONT TO THE STRONG SURFACE
HIGH OVER SIBERIA THAT IS PRODUCING WIDESPREAD EASTERLY GALES ACROSS
THE WESTERN BERING AND ALEUTIANS.

.MODEL DISCUSSION...MODELS ARE IN GOOD AGREEMENT WITH THE GULF
STORM AND SHOW GOOD RUN-TO-RUN CONSISTENCY...SO FORECAST CONFIDENCE
IS ABOVE AVERAGE. ALL MODELS ARE A BIT FURTHER NORTH AND EAST WITH
THE TRACK OF THE LOW ACROSS THE GULF TODAY AND ACROSS THE KENAI
PENINSULA LATE TONIGHT INTO SATURDAY MORNING. THIS MEANS LESS WARM
AIR WILL MAKE IT TO THE EASTERN KENAI PENINSULA THAN WAS INDICATED
THE PAST COUPLE DAYS AND PRECIP WILL REMAIN MOSTLY IF NOT ALL SNOW.
MODELS OFTEN HAVE TROUBLE PINPOINTING THE TRACK OF LOWS INLAND DUE
TO THE COMPLEX TERRAIN. THEREFORE...THERE IS STILL SOME UNCERTAINTY
IN THE TRACK OF THIS LOW. BASED ON THE CURRENT TRACK THERE IS GOOD
POTENTIAL FOR STRONG WINDS TO MOVE INTO PORTAGE VALLEY AND TURNAGAIN
ARM AS THE LOW PASSES BY TONIGHT INTO SATURDAY...THEREBY PRODUCING
BLIZZARD CONDITIONS. HOWEVER...IF THE LOW TRACK WERE JUST A LITTLE
BIT FURTHER NORTH AND EAST THIS WOULD CHANGE THINGS SIGNIFICANTLY.
SO FOR NOW BLIZZARD WATCHES HAVE BEEN ISSUED FOR THESE AREAS.

IT LOOKS LIKE ONE MORE SYSTEM WILL BE DRAWN INTO THE UPPER TROUGH
BEFORE IT EXITS TO THE NORTH ON MONDAY. MODELS HAVE BEEN ALL OVER
THE PLACE WITH THE TRACKING AND STRENGTH OF THIS NEXT SYSTEM. THERE
ARE STILL LARGE DIFFERENCES...BUT THEY ALL SHOW THE SAME GENERAL
IDEA NOW...SO WILL GO WITH A BLEND OF THE SOLUTIONS.

SIMILARLY...THERE IS LARGE DISAGREEMENT WITH MAJOR PACIFIC STORM
APPROACHING THE ALEUTIANS SUNDAY AND MONDAY. WILL STICK CLOSE TO
THE INHERITED FORECAST FOR NOW...WHICH IS CLOSEST TO THE GFS
SOLUTION.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...MOISTURE AND WARM AIR OUT AHEAD OF DEVELOPING
GULF LOW WILL BRING ANOTHER ROUND OF OVERRUNNING SNOW TO SOUTHCENTRAL
THIS AFTERNOON AND EVENING. MEANWHILE...THE UPPER TROUGH WILL SWING
INTO THE GULF AND ARCTIC AIR WILL USHER INTO THE WESTERN GULF...WHICH
IS A LARGE REASON WHY NEW LOW WILL FORM OVER THE CENTRAL GULF. IN
ANY CASE...COLD AIR ADVECTION/STRONG SYNOPTIC LIFT/OVERRUNNING WILL
ALL WORK TOGETHER TO INTENSIFY PRECIPITATION TONIGHT...ESPECIALLY
IN THE PRINCE WILLIAM SOUND REGION.

AS THE LOW MOVES TO THE KENAI PENINSULA THE COLD FRONT WILL RAPIDLY
MOVE NORTH AND EASTWARD CAUSING A BIT OF A COASTAL JET ALONG THE
NORTHEAST GULF COAST INTO PRINCE WILLIAM SOUND...WITH STORM FORCE
WINDS EXPECTED. THIS FRONT WILL PUSH INLAND WHICH MEANS THE EASTERN
PRINCE WILLIAM SOUND REGION (INCLUDING CORDOVA) WILL EXPERIENCE
STRONG WINDS. WARMER AIR WILL TURN PRECIP TO ALL RAIN IN
CORDOVA...BUT PRECIP WILL REMAIN SNOW OVER NORTHEAST PRINCE WILLIAM
SOUND WHERE THE HIGHEST SNOW AMOUNTS ARE EXPECTED. SNOW AND WINDS
THROUGH THOMPSON PASS WILL PRODUCE BLIZZARD CONDITIONS BEGINNING THIS
AFTERNOON AS STEADY SNOW MOVES BACK IN.

AS MENTIONED IN THE MODEL DISCUSSION THERE IS ALSO GOOD POTENTIAL
FOR BLIZZARD CONDITIONS ALONG TURNAGAIN ARM AS THE LOW TRACKS BY
JUST TO THE SOUTH. WIND SPEEDS WILL RAPIDLY INCREASE BEHIND THE
LOW DUE TO INCREASING PRESSURE GRADIENT AS WELL AS RAPID PRESSURE
RISES. BASED ON THIS LOW TRACK IT DOES NOT LOOK LIKE DOWNSLOPE WINDS
WILL PLAY MUCH OF A ROLE ON THE LEE SIDE OF THE CHUGACH AND KENAI
MOUNTAINS DUE TO THE DEPTH OF THE ARCTIC AIR AND THE FACT THAT THE
STRONGEST WARM ADVECTION WILL STAY FURTHER EAST. THEREFORE...THE
STRONGEST WINDS WILL STAY ABOVE MOUNTAIN TOP AND PRODUCE LITTLE IN
THE WAY OF A DOWNSLOPE EFFECT. THEREFORE...ANCHORAGE AND THE WESTERN
KENAI WILL LIKELY SEE A LONG DURATION OF SNOW FROM NOW THROUGH
SATURDAY MORNING. EVEN AS THE STRONGEST WINDS KICK UP BEHIND THE
LOW ARCTIC AIR WILL RAPIDLY RUSH UP COOK INLET AND PROVIDE EXTRA
LIFT...POSSIBLY PRODUCING A BURST OF HEAVIER SNOW SATURDAY MORNING.
FOR NOW WILL TREND TOWARD SLIGHTLY HIGHER SNOW AMOUNTS WITH THE NEW
FORECAST...BUT WILL HAVE TO WAIT UNTIL WE KNOW WHERE THE LOW WILL
TRACK BEFORE DETERMINING IF SNOW AMOUNTS WILL BE EVEN HEAVIER.

THE LOW WILL TRACK RAPIDLY INLAND SATURDAY AS UPPER LOW AND TROUGH
SWING NORTHWARD. ARCTIC AIR WILL SPREAD ACROSS ALL OF SOUTHCENTRAL
CHANGING PRECIP TO BACK TO ALL SNOW AND THEN TAPERING THE SNOW OFF
TO SHOWERS. IT DOES LOOK LIKE ANOTHER STORM WILL MOVE UP FROM THE
PACIFIC SUNDAY AND MOVE ACROSS SOUTHCENTRAL MONDAY...BUT THERE IS
HIGH UNCERTAINTY RIGHT NOW AS TO WHERE THIS STORM WILL TRACK. IT
VERY WELL COULD LEAD TO ANOTHER ROUND OF SNOW ACROSS THE REGION.

SOUTHWEST ALASKA...KIPNUK IS THE ONLY OBSERVATION SITE IN THE
KUSKOKWIM DELTA CURRENTLY MEETING WIND CHILL CRITERIA OF 40 BELOW
ZERO...BUT TEMPERATURES WILL CONTINUE TO SLOWLY DROP ACROSS THE
DELTA TONIGHT AND EXPECT MORE LOCATIONS TO DROP DOWN TO THAT LEVEL.
AN AREA OF SNOW HAS DEVELOPED ALONG THE ALASKA PENINSULA SOUTH OF
KING SALMON THIS MORNING. EXPECT MORE CLOUDS AND SNOW TO DEVELOP
FROM BRISTOL BAY TO THE SOUTHERN KUSKOKWIM VALLEY TONIGHT AND
SPREAD BACK AS FAR WEST AS THE KUSKOKWIM DELTA SATURDAY AS THE
UPPER LOW TRACKS BACK NORTHWARD ACROSS SOUTHWEST ALASKA PULLING
SOME MOISTURE IN FROM THE GULF. THUS...WILL UP PROBABILITY OF
PRECIP WITH THE NEW FORECAST.

BERING SEA/ALEUTIANS...COLD ADVECTION SNOW SHOWERS AND NORTHERLY
WINDS WILL DIMINISH SATURDAY AND TAPER OFF SUNDAY AS UPPER TROUGH
LIFTS BACK TO THE NORTH. THE PRESSURE GRADIENT WILL SLACKEN OVER
THE WESTERN BERING AND ALEUTIANS TONIGHT AND SATURDAY AS THE
OCCLUDED FRONT FALLS APART AND HIGH PRESSURE BUILDS SOUTHWARD. A
MAJOR PACIFIC STORM IS THEN EXPECTED TO BEGIN IMPACTING THE REGION
SUNDAY AS A GALE FORCE FRONT PUSHES NORTHWARD INTO THE SOUTHERN
BERING. THERE IS LOW CONFIDENCE IN WHERE THIS STORM WILL TRACK...BUT
HIGH CONFIDENCE THAT A LARGE PART OF THE REGION WILL BE IMPACTED
BY IT NEXT WEEK.

.LONG TERM FORECAST...A HIGH AMPLITUDE TROUGH WILL BE CENTERED
OVER THE BERING AND NORTH CENTRAL PACIFIC. SO...CORRESPONDING TO
THIS IT LOOKS LIKE A MAJOR STORM WILL MOVE FROM THE PACIFIC INTO
THE BERING NEXT WEEK PRODUCING WIDESPREAD IMPACTS ACROSS ALASKA.
SINCE THE SOUTHERN MAINLAND WILL BE ON THE WARM SIDE OF THE SYSTEM
EXPECT MODERATING TEMPERATURES AS WE HEAD THROUGH THE WEEK.
MEANWHILE...WEST OF THE SYSTEM THE CENTRAL TO WESTERN BERING
WILL LIKELY SEE STRONG COLD ADVECTION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 131. BLIZZARD WATCH 101 125.
MARINE...STORM WARNING...120 125.
         GALE WARNING...127 128 172 175 176.
         HEAVY FREEZING SPRAY WARNING...130 138 140 141 150 155
                                        160  165 179 185.
FIRE WEATHER...NONE.

SEB FEB 10