Gale Warning 65, NWS Fairbanks, AK

172 
FZAK52 PAFG 291105
CWFWCZ

COASTAL WATERS FORECAST FOR NORTHWEST ALASKA
NATIONAL WEATHER SERVICE FAIRBANKS AK
305 AM AKDT SAT SEP 29 2012

NORTHWESTERN ALASKA COASTAL WATERS OUT 100 NM

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

PKZ299-300215-
305 AM AKDT SAT SEP 29 2012

.SYNOPSIS FOR NORTHWEST COAST...
1011 MB HIGH PRESSURE OVER THE EASTERN CHUKCHI SEA WILL BUILD
EASTWARD OVER THE BEAUFORT SEA BY SUN AM. 990 MB LOW WILL ENTER
THE WESTERN BERING SEA SAT PM. IT WILL BE A 988 MB LOW NEAR 60N
180W SUN PM...AND A 994 MB LOW NEAR SAINT MATTHEW ISLAND MON PM.
LOW PRESSURE OVER THE INTERIOR OF ALASKA WILL CONTINUE TO WEAKEN. 

$$

PKZ200-300215-
NORTON SOUND-
305 AM AKDT SAT SEP 29 2012

.TODAY...N WINDS 15 KT. LOCAL GUSTS TO 20 KT NEAR SHORE FROM
NORTON BAY TO SLEDGE ISLAND. SEAS 3 FT SUBSIDING.
.TONIGHT...W WINDS 5 KT. SEAS 2 FT. 
.SUN...S WINDS 20 KT. SEAS 4 FT. 
.SUN NIGHT...SE WINDS 35 KT. SEAS 7 FT. 
.MON...SE WINDS 30 KT. SEAS 7 FT. 
.MON NIGHT...SE WINDS 30 KT. SEAS 6 FT. 
.TUE...S WINDS 30 KT. SEAS 6 FT. 
.WED...E WINDS 20 KT. SEAS 4 FT.  

$$

PKZ210-300215-
DALL POINT TO WALES-
305 AM AKDT SAT SEP 29 2012

...SMALL CRAFT ADVISORY IN EFFECT FROM TONIGHT THROUGH EARLY
SUNDAY MORNING...

.TODAY...N WINDS 20 KT DECREASING TO 15 KT. SEAS 7 FT SUBSIDING
TO 5 FT.
.TONIGHT...S WINDS 25 KT. SEAS 6 FT. 
.SUN...SE WINDS 30 KT. SEAS 8 FT. 
.SUN NIGHT...SE WINDS 35 KT. SEAS 9 FT. 
.MON...SE WINDS 30 KT. SEAS 9 FT. 
.MON NIGHT...SE WINDS 30 KT. SEAS 7 FT. 
.TUE...S WINDS 25 KT. SEAS 7 FT. 
.WED...E WINDS 30 KT. SEAS 9 FT.  

$$

PKZ215-300215-
KOTZEBUE SOUND-
305 AM AKDT SAT SEP 29 2012

.TODAY...N WINDS 15 KT. SEAS 3 FT SUBSIDING. 
.TONIGHT...W WINDS 5 KT. SEAS 1 FT. 
.SUN...S WINDS 10 KT. SEAS 3 FT. 
.SUN NIGHT...SE WINDS 30 KT. SEAS 6 FT.
.MON...SE WINDS 30 KT. SEAS 7 FT.
.MON NIGHT...SE WINDS 30 KT. SEAS 6 FT.
.TUE...SE WINDS 30 KT. SEAS 6 FT. 
.WED...S WINDS 20 KT. SEAS 4 FT.  

$$

PKZ220-300215-
WALES TO CAPE THOMPSON-
305 AM AKDT SAT SEP 29 2012

.TODAY...N WINDS 20 KT. SEAS 6 FT. 
.TONIGHT...E WINDS 10 KT. SEAS 4 FT. 
.SUN...S WINDS 25 KT. SEAS 5 FT. 
.SUN NIGHT...SE WINDS 30 KT. SEAS 6 FT. 
.MON...SE WINDS 35 KT. SEAS 9 FT. 
.MON NIGHT...SE WINDS 30 KT. SEAS 8 FT. 
.TUE...S WINDS 35 KT. SEAS 8 FT. 
.WED...S WINDS 15 KT. SEAS 3 FT.  

$$

TF/JK SEP 12

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
530 AM AKDT FRI SEP 28 2012

.DISCUSSION...
THE NAM AND GFS COMPUTER WEATHER FORECAST MODELS AGREE CLOSELY ON
THE PROJECTIONS THROUGH SATURDAY NIGHT. INDEED...THE MODELS USED
FOR THIS MORNINGS FORECASTS ARE NICELY FOLLOWING THE FORECASTS
FROM EARLIER MODEL RUNS.

THE LARGE TROUGH OF LOW PRESSURE ALOFT EXTENDING FROM THE HIGH
ARCTIC SOUTHWARD OVER THE ALASKA MAINLAND IS FORECAST TO EXIT INTO
NORTHWEST CANADA ON SUNDAY. A NEW LOW PRESSURE SYSTEM WILL MOVE
INTO THE WESTERN BERING SEA NEAR CAPE NAVARIN EARLY SUNDAY. HIGH
PRESSURE AHEAD OF THIS LOW WILL BUILD OVER MAINLAND ALASKA
STARTING SUNDAY...AND TAKE UP RESIDENCE FOR THE REST OF THE WEEK.

THE LOW PRESSURE OVER THE EASTERN BERING SEA WILL BRING BOUTS OF
BRISK SOUTHEAST WINDS...PERHAPS BRIEFLY REACHING GALE
STRENGTH...ALONG WITH RAIN TO THE WEST COAST. SOUTHEAST WINDS IN
THAT AREA ORIGINATE FROM WARMER REGIONS AND RESULT IN THE INFLUX
OF A STABLE AIR MASS.

THIS IS THE OPPOSITE OF THE BRISK NORTH WINDS WHICH HAVE BEEN
BLOWING OVER WESTERN ALASKA FOR THE PAST SEVERAL DAYS. COMING FROM
A COLDER REGION TO THE DISTANT NORTH...THE NORTHERLY CIRCULATION
BRINGS COLD AIR TO AN AREA WARMER THAN ITS ORIGIN...AND THUS FORMS
AN UNSTABLE AIR MASS. THE WIND GUSTS IN AN UNSTABLE AIR MASS ARE
LARGER THAN THOSE IN A STABLE AIR MASS.

ANOTHER RESULT OF THE UNSTABLE AIR MASS NOW OVER THE ARCTIC AND
WESTERN COASTS OF NORTHERN ALASKA IS RELATIVELY STEADY CEILING
HEIGHTS DUE TO THE WELL MIXED UNSTABLE AIR MASS. THE AVIATION
WEATHER IN THESE AREAS HAS BEEN STEADIER THAN IT TYPICALLY IS IN
PERIODS OF ONSHORE FLOW OF STABLE AIR.

A FINAL RESULT OF THE INSTABILITY OF THE ARCTIC AND WEST COAST AIR
MASS IS THE ABSENCE OF FREEZING RAIN...WHICH ALMOST ALWAYS OCCURS
IN STABLE AIR MASSES. IN THESE SITUATIONS...MOIST AIR WITH
TEMPERATURES ABOVE FREEZING FLOATS ABOVE AIR WITH TEMPERATURES
WELL BELOW FREEZING DOWN TO THE SURFACE. FORTUNATELY...TODAYS
WEATHER PATTERN DIFFERS COMPLETELY WITH THAT OF A FREEZING RAIN
EVENT.

EARLY MORNING POLAR ORBITING SATELLITE IMAGERY SHOWS STRONG
CIRCULATION OVER THE MACKENZIE DELTA OF CANADA. A TROUGH OF LOW
PRESSURE AT THE SURFACE EXTENDS WESTWARD FROM THE LOW JUST
OFFSHORE THE ARCTIC COAST AT FLAXMAN ISLAND. BRISK WEST WINDS HAVE
BEEN BLOWING OVER THIS SECTION OF THE COAST SINCE MID DAY
THURSDAY. THIS TROUGH IS A COMMON FEATURE OF CIRCULATION OVER THE
EASTERN ARCTIC COAST OF ALASKA. THE NUMERICAL FORECAST MODELS ARE
CONSISTENTLY PROJECTING THIS FEATURE TO DISSIPATE AT MID DAY TODAY.
THE BRISK WEST WINDS OF THIS MORNING WILL QUICKLY WEAKEN AND
BECOME NORTHEAST AS THIS OCCURS.

THE MEDIUM RANGE FORECAST MODELS AGREE WELL IN THE TREND THROUGH
THE END OF NEXT WEEK...HIGH PRESSURE ALOFT WILL BUILD AND HOLD
OVER THE EASTERN AND CENTRAL MAINLAND...WHILE PERSISTENT LOW
PRESSURE OVER THE BERING SEA WILL CONTINUE TO BRING UNSETTLED
WEATHER TO THE WEST COAST. BEYOND THE END OF NEXT WEEK...THE
NUMERICAL MODELS DIVERGE...AND THE OUTLOOK IS TYPICALLY UNCERTAIN.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.HYDROLOGY...
NORTHERN ALASKA RIVERS ARE WELL WITHIN THEIR BANKS. STAGES ON MOST
NORTHERN ALASKA RIVERS ARE EITHER LEVEL OR SLOWLY FALLING. THERE
IS A MINOR RISE IN PROGRESS ON THE YUKON RIVER FROM THE DALTON
HIGHWAY DOWN TO GALENA. LITTLE PRECIPITATION IS EXPECTED IN
NORTHERN ALASKA DURING THE NEXT TWO DAYS. THE INCOMING NORTHWEST
BERING SEA LOW IS EXPECTED TO BRING RAIN TO MUCH OF THE WEST COAST
STARTING SUNDAY...BUT THE AMOUNT OF RAIN IS NOT FORECAST TO BE
LARGE ENOUGH FOR MUCH RESPONSE ON THE RIVERS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ245.
&&

TF SEP 12