Gale Warning 828, NWS Anchorage, AK

189 
FZAK62 PAFC 040033
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
333 PM AKST THU DEC 3 2015

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.

PKZ499-041445-
333 PM AKST THU DEC 3 2015
.SYNOPSIS FOR CENTRAL BERING SEA...
A FRONT OVER THE SOUTHERN BERING WEAKENS AS IT MOVES INTO THE
EASTERN BERING LATE THU NIGHT...THEN DISSIPATES BY FRI AFTERNOON.
A 992 MB LOW NEAR 56N 168W DEVELOPS ALONG THE DISSIPATING FRONT
FRI AFTERNOON...THEN MOVES TO 58N 169W AT 990 MB SAT AFTERNOON.

$$

PKZ411-041445-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE-
333 PM AKST THU DEC 3 2015

.TONIGHT...N WIND 20 TO 30 KT. SEAS 10 TO 16 FT. FREEZING SPRAY N
OF 57N.
.FRI...N WIND 15 TO 20 KT. SEAS 8 TO 11 FT.
.FRI NIGHT...NE WIND 15 TO 25 KT. SEAS 7 FT.
.SAT...NE WIND 15 TO 25 KT. SEAS 6 TO 9 FT.
.SAT NIGHT...NE WIND 25 KT. SEAS 8 TO 13 FT.
.SUN THROUGH TUE...NW WIND 15 TO 30 KT. SEAS 8 TO 16 FT.

$$

PKZ412-041445-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N-
333 PM AKST THU DEC 3 2015

.TONIGHT...N WIND 20 TO 30 KT. SEAS 9 TO 14 FT. FREEZING SPRAY N
OF 58N.
.FRI...N WIND 10 TO 20 KT. SEAS 7 TO 10 FT.
.FRI NIGHT...N WIND 10 TO 15 KT. SEAS 4 TO 8 FT.
.SAT...NE WIND UP TO 15 KT. SEAS 3 TO 6 FT.
.SAT NIGHT...NE WIND 10 TO 20 KT. SEAS 5 TO 8 FT.
.SUN THROUGH TUE...NW WIND 15 TO 30 KT. SEAS 8 TO 16 FT.

$$

PKZ413-041445-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N-
333 PM AKST THU DEC 3 2015

...GALE WARNING TONIGHT...

.TONIGHT...N WIND 20 TO 35 KT. SEAS 10 TO 15 FT. RAIN AND SNOW.
.FRI...N WIND 15 TO 25 KT. SEAS 9 FT.
.FRI NIGHT...N WIND 10 TO 15 KT. SEAS 6 FT.
.SAT...NE WIND UP TO 20 KT. SEAS 4 TO 7 FT.
.SAT NIGHT...NE WIND 15 TO 25 KT. SEAS 7 FT.
.SUN THROUGH TUE...NW WIND 20 TO 35 KT. SEAS 9 TO 17 FT.

$$

PKZ414-041445-
BERING SEA OFFSHORE EAST OF 171W-
333 PM AKST THU DEC 3 2015

.TONIGHT...NE WIND 10 TO 30 KT. SEAS 6 TO 10 FT. PATCHY FOG. RAIN
AND SNOW. FREEZING SPRAY N OF 58N.
.FRI...NE WIND 10 TO 25 KT. SEAS 5 TO 9 FT. PATCHY FOG. FREEZING
SPRAY N OF 57N.
.FRI NIGHT...N WIND 10 TO 20 KT. SEAS 4 TO 7 FT.
.SAT...E WIND UP TO 15 KT. SEAS 4 FT.
.SAT NIGHT...E WIND 10 TO 20 KT. SEAS 5 FT.
.SUN THROUGH MON...NE WIND 15 TO 25 KT. SEAS 5 TO 10 FT.
.TUE...NW WIND 25 KT. SEAS 8 TO 13 FT.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
358 PM AKST WED DEC 2 2015

NOTE...NWS FAIRBANKS AND NWS JUNEAU ISSUED ALL NWS ANCHORAGE
PRODUCTS TODAY. ONLY THE SHORT TERM FORECAST DISCUSSIONS BELOW
WERE UPDATED. THIS WAS PART OF A PLANNED PRACTICE BACKUP. NWS
FAIRBANKS AND JUNEAU WILL DEFER NORMAL OPERATIONS BACK TO WFO
ANCHORAGE AT 4 PM AKST TODAY.

.PREV DISCUSSION... /ISSUED 504 AM AKST WED DEC 2 2015/

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL LOW IS POSITIONED OVER THE SOUTHWESTERN GULF
REGION WITH AN INVERTED TROUGH EXTENDING THROUGH KODIAK ISLAND
INTO THE LOWER COOK INLET THIS MORNING. THESE SYNOPTIC FEATURES
ARE REFLECTED AT THE SURFACE WITH A 982 MB LOW JUST SOUTH OF THE
CHIRIKOF ISLANDS AND A 983 MB LOW EAST OF THE BARREN ISLANDS. AN
ASSOCIATED WEATHER FRONT FROM THE 983 MB LOW EXTENDS NORTHWARD
ALONG THE EASTERN KENAI PENINSULA THROUGH THE PRINCE WILLIAM SOUND
REGION INTO THE CHUGACH MOUNTAINS. THE SATELLITE IMAGERY COINCIDES
WITH SHOWING A LARGE SWATH OF WRAP-AROUND MOISTURE IN THE EASTERN
ALEUTIANS/ALASKA PENINSULA...THE NORTHWESTERN GULF THROUGH PRINCE
WILLIAM SOUND INTO THE COPPER RIVER BASIN. WHILE AT THE SAME TIME
THE RADAR IMAGERY IS SHOWING NUMEROUS SHOWERS IN THE NORTHERN GULF
MOVING INTO THE PRINCE WILLIAM SOUND...THE KENAI MOUNTAINS...THE
ANCHORAGE BOWL AND SPREADING INTO THE MAT-SU REGION THIS MORNING.
THE SURFACE OBSERVATION AT THE ANCHORAGE AIRPORT IS REPORTING LIGHT
SNOW. WHILE OUT WEST...THERE IS A SURFACE RIDGE OF HIGH PRESSURE
OVER THE CENTRAL BERING SEA WITH THE ASCAT SCATTEROMETER DATA SHOWING
NORTHWESTERLY WINDS FROM THE NORTHERN TO EASTERN BERING SEA INTO
THE PACIFIC OCEAN. AT 500 MB THERE IS A CLOSED LOW JUST WEST OF
SHEMYA WITH A RIDGE DOWNSTREAM OVER THE CENTRAL ALEUTIANS. AT THE
SURFACE THIS IS REFLECTED WITH A STORM FORCE LOW NEAR 53N 171E
WITH AN ASSOCIATED WEATHER FRONT THROUGH THE WESTERN/CENTRAL
ALEUTIANS JUST WEST OF ADAK. THIS SYSTEM IS RECEIVING SUPPORT FROM
A STRONG 160 KNOT NORTHWESTERLY JET STREAM DIGGING DOWN INTO THE
BASE OF THE LONGWAVE TROUGH.

.MODEL DISCUSSION...
THE MODELS REMAIN IN GOOD AGREEMENT WITH THE LOW JUST SOUTH OF
CHIRIKOF ISLAND AS IT GET PHASED IN WITH THE STRONGER NORTH
PACIFIC LOW NEAR 52N 143W THIS MORNING. BY THURSDAY THE MODELS
HAVE DIFFICULTY WITH PLACEMENT OF THIS LOW AS IT TRACKS TO THE
NORTHEAST. THE NAM WAS THE PREFERRED MODEL IN THE SHORT TERM AND
THE ECMWF WAS THE OUTLIER WITH THIS SYSTEM. IN THE BERING THE NEXT
SYSTEM TRACKS OFF THE KAMCHATKA PENINSULA AND THE MODELS STRUGGLE
WITH PLACEMENT AND STRENGTH OF THIS SYSTEM. THE NAM/GFS MODELS
WERE IN DECENT AGREEMENT AND THE ECMWF WAS FASTER WITH THIS
SYSTEM. BY THURSDAY EVENING THIS LOW TRACKS SOUTH OF THE
CENTRAL/EASTERN ALEUTIANS AND BECOMES A COMPLEX SYSTEM WITH
MULTIPLE LOW PRESSURE CENTERS. THE FORECAST CONFIDENCE IS AVERAGE
THROUGH THE SHORT-TERM AND BEGINS TO DIMINISH AS THIS SYSTEM
BECOMES COMPLEX.

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND
2).../UPDATED WED 4PM AKST/ SHOWERS PHASED OUT ACROSS SC AK TODAY
LEAVING FLAT CLOUD DECKS IN THE LOW AND MID LEVELS. THE FORECAST
AREA LIES UNDER A STABLE AIR MASS IN BETWEEN WEATHER
SYSTEMS...ONE OVER THE ERN GULF AND ANOTHER APPROACHING THE AKPEN.
MODEL GUIDANCE SHOWS LITTLE IN THE WAY OF MOISTURE ADVECTING
TOWARD SOUTH CENTRAL SO EXPECTING CLOSE TO STATUS QUO CONDITIONS
THROUGH THURS. THE LOW PRESSURE CENTERS AND FRONTS MENTIONED TO
THE SE AND SW MOVE CLOSER TO THE FORECAST AREA BUT NOT CLOSE
ENOUGH TO CAUSE SIGNIFICANT CHANGE IN THE WEATHER. EXPECT LOCAL
INFLUENCES WILL DOMINATE..SUCH AS SLIGHT HIGHER CHANCE OF SNOW
SHOWERS ON S-SE FACING TERRAIN.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
A WEAK UPPER LEVEL TROUGH IS MOVING TOWARDS THE SOUTHWEST COAST
THIS AFTERNOON WITH INCREASING SCATTERED SNOW SHOWERS EXPECTED
THROUGH THE LATE AFTERNOON. THE SNOW SHOWERS HAVE ALREADY STARTED
MAKING ITS WAY TO THE KUSKOKWIM DELTA AREA INCLUDING NAPAKIAK AND
KWETHLUK AND THE BRISTOL BAY AREA. THE CHANCE FOR SNOW SHOWERS
WILL CONTINUE TO MOVE INLAND OVERNIGHT AND DECREASE TO ISOLATED
SNOW SHOWERS BY THURSDAY MORNING. AS THE TROUGH MOVES FURTHER
INLAND SNOW SHOWERS WILL DEVELOP ON THURSDAY NIGHT ACROSS PORTIONS
OFTHE LOWER KUSKOKWIM VALLEY EAST OF LIME VILLAGE. FOR OTHER
AREAS THE THE DRIER AND COLD CONDITIONS WILL HANG AROUND UNTIL
FRIDAY MORNING WHEN A WEAKENING FRONT WILL PUSH IN FROM THE SOUTH
OVER THE ALASKA PENINSULA.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A STRONG LOW PRESSURE SYSTEM IS EXPECTED TO WEAKEN SLIGHTLY TO
969 MB AND BE LOCATED 250NM SOUTH OF ATTU. THE STORM FORCE FRONT
ASSOCIATED WITH IT WILL SLOWLY PROGRESS EASTWARD WHILE WEAKENING
AS IT MOVES TOWARDS THE EASTERN ALEUTIANS BY THURSDAY
MORNING. THERE WILL BE A TRANSITION OF SNOW TO A WINTRY MIX OF
RAIN AND SNOW BRIEFLY ACROSS THE EASTERN ALEUTIANS EARLY THURSDAY
MORNING...THEN TO RAIN SHOWERS THROUGH THE LATE MORNING INTO EARLY
AFTERNOON. THE MAIN AREA OF LOW PRESSURE WILL MOVE SOUTH OF THE
CHAIN WITH SEVERAL LOW CENTERS AND CIRCULATIONS. ON
THURSDAY...ARCTIC AIR FILTERING DOWN FROM THE BERING STRAIT WILL
BE THE FOCUS FOR SCATTERED SNOW SHOWERS OVER THE WESTERN AND
CENTRAL BERING SEA.

&&

.PREV LONG TERM FORECAST (DAYS 3 THROUGH 7)...

HEADED INTO THE MID-TERM...THE FORECAST AREA WILL BE DOMINATED BY
LARGE LOW CENTERED SOUTH OF THE EASTERN ALEUTIANS AROUND 50N 165W.
THIS LOW...EXPECTED TO BE AROUND 980 MB...IS EXPECTED TO MOVE EAST
ALONG 50N INTO THE SOUTHERN GULF AND DEEPEN TO THE MID-960 MB
RANGE BY SATURDAY MORNING. MODELS HAVE COME INTO BETTER AGREEMENT
THAN PREVIOUS PACKAGES WITH THE DEVELOPMENT OF THIS SYSTEM AS IT
PROGRESSES EAST. THIS WILL BRING BROAD CYCLONIC FLOW TO THE
REGION...WITH COLD AND DRY CONDITIONS OVER MOST OF SOUTHWEST
ALASKA AND INTERIOR SOUTH CENTRAL WITH SHOWERS ALONG COASTAL
REGIONS THROUGH SUNDAY MORNING. THIS LOW IS EXPECTED TO PUSH
EASTWARD INTO SOUTHEAST ALASKA AND FALL APART BY SUNDAY NIGHT.

MEANWHILE...FURTHER WEST...ENERGY FROM A LOW JUST SOUTH OF THE
KAMCHATKA PENINSULA ON THURSDAY EVENING WILL PUSH EAST ALONG AND
SOUTH OF THE ALEUTIAN CHAIN AND DEEPEN TO ABOUT 960 MB SOUTH OF
ADAK BY LATE SATURDAY EVENING. GLOBAL MODELS ARE HANDLING THIS
FEATURE DECENT WITH FAIR AGREEMENT BETWEEN THE GFS AND EC. A
SECOND LOW IS EXPECTED TO DEVELOP IN THE SOUTHWEST QUADRANT OF
THIS LOW AROUND 40N 170E ON SUNDAY MORNING. WITH THIS FEATURE...MODELS
BEGIN TO DIVERGE WITH THE GFS DEVELOPING THE LOW FURTHER TO THE
EAST AND MOVING IT FASTER EASTWARD. THE EC IS FURTHER TO THE
NORTHWEST BUT DEVELOPS A SLIGHTLY STRONGER LOW /972 MB ON THE GFS
TO 968 MB ON THE EC/ BY SUNDAY AFTERNOON. AFTER THIS POINT...MODEL
GUIDANCE BEGINS TO DIVERGE. BOTH MODELS BASICALLY OPEN THE FIRST
LOW INTO AN INVERTED TROUGH OVER THE EASTERN BERING WITH THE
BACKSIDE LOW BECOMING THE DOMINATE LOW OVER THE THE NORTH PACIFIC
BY EARLY MONDAY MORNING. BOTH THE EC AND GFS CREATE A DEEP LOW IN
THE MID 950 MB RANGE SOUTH OF THE ALASKA PENINSULA AROUND 45N WITH
THE GFS A FASTER AND MORE EASTERN SOLUTION. GOING INTO DAY
7...MODELS BRIEFLY DEEPEN THE LOW INTO THE UPPER 940S BEFORE
PUSHING THE LOW INTO THE SOUTHEASTERN GULF OF ALASKA WITH A
PRESSURE AROUND 950 MB BY EARLY ON DAY 7.

WITH MODEL GUIDANCE IN FAIR AGREEMENT ON DAY 3...THE GFS WAS USED
FOR UPDATES. WPC GUIDANCE WAS USED FOR DAYS 4 THROUGH 7...WHICH
WAS BASED HEAVILY ON 00Z GEFS AND EC ENSEMBLE GUIDANCE. THERE IS
ENOUGH UNCERTAINTY ON THE EVOLUTION OF THE TWO LOWS FOR DAYS 4-7
TO KEEP DETAILS VERY GENERALIZED IN THE FORECAST PACKAGE AT THIS
POINT WITH A LOW TO MODERATE CONFIDENCE IN THE EXTENDED PACKAGE.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 173 178
         HEAVY FREEZING SPRAY...160 185

&&