Storm Warning 257, NWS Anchorage, AK

971 
FZAK62 PAFC 141209
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 AM AKST WED DEC 14 2011

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.

PKZ499-150300-
400 AM AKST WED DEC 14 2011
.SYNOPSIS FOR CENTRAL BERING SEA...

A 960 MB LOW NEAR 56N 177E WILL MOVE TO 56N 163E AT 973 MB THU
MORNING...THEN MOVE ASHORE THE KAMCHATKA PENINSULA. A 964 MB LOW NEAR
49N 169W WILL MOVE TO 55N 165W AT 942 MB EARLY THU MORNING...THEN
TRACK TO 58N 164W AT 967 MB FRI MORNING.

$$

PKZ411-150300-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE
400 AM AKST WED DEC 14 2011

...STORM WARNING TODAY...

.TODAY...N OF 56N...E WIND 50 KT. S OF 56N...W WIND 50 DIMINISHING TO
35 KT IN THE AFTERNOON. SEAS 22 TO 25 FT. SNOW SHOWERS. 
.TONIGHT...N OF 56N...E WIND 40 KT. S OF 56N...W WIND 25 TO 35 KT.
SEAS 19 TO 23 FT. SNOW AND RAIN SHOWERS. 
.THU...N OF 56N...NE WIND 40 KT. S OF 56N...N WIND 15 TO 25 KT. SEAS
19 TO 23 FT. SNOW AND RAIN SHOWERS.
.THU NIGHT...NE WIND 35 KT. SEAS 23 FT. 
.FRI...NE WIND 35 KT. SEAS 21 FT. 
.SAT...N WIND 30 KT. SEAS 18 FT. 
.SUN...NW WIND 30 KT. SEAS 17 FT.  

$$

PKZ412-150300-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N
400 AM AKST WED DEC 14 2011

...GALE WARNING THROUGH THURSDAY...

.TODAY...E WIND 45 KT. SEAS 18 TO 22 FT. RAIN AND SNOW. 
.TONIGHT...NE WIND 45 KT. SEAS 23 FT. SNOW AND RAIN. 
.THU...NE WIND 45 KT. SEAS 24 FT. SNOW AND RAIN SHOWERS.
.THU NIGHT...N WIND 45 KT. SEAS 24 FT. 
.FRI...N WIND 35 KT. SEAS 19 FT. 
.SAT...N WIND 25 KT. SEAS 16 FT. 
.SUN...W WIND 35 KT. SEAS 15 FT.  

$$

PKZ413-150300-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N
400 AM AKST WED DEC 14 2011

...GALE WARNING THROUGH THURSDAY...

.TODAY...W OF 176W...S WIND 35 KT BECOMING W 25 KT IN THE AFTERNOON.
E OF 176W...SE WIND 25 KT BECOMING NE 45 KT IN THE AFTERNOON. SEAS 15
TO 19 FT. SNOW AND RAIN. 
.TONIGHT...N WIND 30 TO 45 KT. SEAS 18 TO 23 FT. RAIN AND SNOW. 
.THU...N WIND 40 KT. SEAS 23 FT. RAIN AND SNOW SHOWERS. 
.THU NIGHT...N WIND 35 KT. SEAS 22 FT. 
.FRI...NE WIND 30 KT. SEAS 19 FT. 
.SAT...W WIND 25 KT. SEAS 15 FT. 
.SUN...W WIND 35 KT. SEAS 15 FT.  

$$

PKZ414-150300-
BERING SEA OFFSHORE EAST OF 171W
400 AM AKST WED DEC 14 2011

...STORM WARNING THROUGH THURSDAY...

.TODAY...E WIND 35 KT INCREASING TO 50 KT IN THE AFTERNOON. SEAS
13 TO 17 FT. RAIN AND SNOW. 
.TONIGHT...E WIND 55 KT. SEAS 23 FT. RAIN AND SNOW. 
.THU...NE WIND 50 KT. SEAS 18 TO 23 FT. SNOW AND RAIN SHOWERS. 
.THU NIGHT...N WIND 45 KT. SEAS 17 FT. 
.FRI...SW WIND 35 KT. SEAS 14 FT. 
.SAT...S WIND 30 KT. SEAS 10 FT. 
.SUN...SW WIND 35 KT. SEAS 12 FT.  

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1245 PM AKST TUE DEC 13 2011

.ANALYSIS AND UPPER LEVELS...A HURRICANE FORCE LOW JUST NORTH OF
THE CENTRAL ALEUTIANS IS THE DOMINANT FEATURE ON SATELLITE THIS
MORNING. THE LOW HAS BOTTOMED OUT AND IS BEGINNING TO VERY SLOWLY
WEAKEN AS IT TRACKS OFF TO THE NORTHWEST. A HIGH AMPLITUDE RIDGE
IS LOCATED DOWNSTREAM OF THIS SYSTEM OVER SOUTHWEST ALASKA AND THIS
IS HELPING TO SLOW THE PROGRESSION OF THE OCCLUDED FRONT. THE FRONT
IS ALSO ELONGATING AND WEAKENING ALONG THE WEST SIDE OF THIS RIDGE.
HEADING FURTHER DOWNSTREAM A WEAK UPPER TROUGH IS MOVING THROUGH
SOUTHCENTRAL ALASKA PRODUCING SOME SNOW SHOWERS FROM EASTERN PRINCE
WILLIAM SOUND TO THE COPPER RIVER BASIN. PATCHY STRATUS AND FOG
HAVE DEVELOPED IN THE WAKE OF THIS TROUGH.

THE NEXT MAJOR STORM TO AFFECT THE ALASKA REGION IS TAKING SHAPE
OVER THE NORTH CENTRAL PACIFIC IN THE LEFT EXIT REGION OF A 180 KT
JET.

.MODEL DISCUSSION...THERE CONTINUES TO BE MODEL DIFFERENCES WITH
TRIPLE POINT DEVELOPMENT SOUTH OF KODIAK ISLAND THIS AFTERNOON. THE
ECMWF IS AN OUTLIER WITH A STRONGER FURTHER SOUTH LOW WHILE THE NAM
IS THE WEAKEST SOLUTION. WILL GO RIGHT DOWN THE MIDDLE CLOSE TO THE
GFS/EKMET/GEM SOLUTIONS. DIFFERENCES REMAIN EARLY ON WITH DEVELOPMENT
OVER THE NORTH PACIFIC. THE GFS/UKMET CONTINUE TO DEPICT A SINGLE
LOW SOLUTION WHILE THE OTHER MODELS DEVELOP A SECONDARY LOW AT THE
BASE OF THE UPPER TROUGH WHICH RAPIDLY DEEPENS AND BECOMES THE MAIN
LOW CENTER. IN CASES OF STRONG UPPER LEVEL SUPPORT LIKE THIS IT IS
COMMON TO SEE SECONDARY LOW DEVELOPMENT SO BELIEVE THAT IS THE MOST
LIKELY SCENARIO. EVEN WITH THIS MODEL DIFFERENCE EARLY ON ALL MODELS
COMMON INTO GOOD AGREEMENT ON LOW POSITION AND STRENGTH BY 42
HOURS...SO CONFIDENCE IS ABOVE AVERAGE WITH THIS SYSTEM.

.SHORT TERM FORECAST...

TRIPLE POINT LOW WILL DEVELOP SOUTH OF KODIAK ISLAND THIS AFTERNOON
WHICH WILL HASTEN THE DEMISE OF THE FRONT OVER THE EASTERN BERING
SEA AS FLOW OVER SOUTHWEST ALASKA BACKS TOWARD THE NORTH. AN UPPER
LEVEL SHORT-WAVE TROUGH WILL QUICKLY LIFT NORTHEASTWARD ACROSS THE
GULF WEDNESDAY TAKING THE LOW WITH IT. KODIAK ISLAND AND THE
GULF COAST WILL SEE MOST OF THE PRECIP AND WINDS WITH THIS WEAK
SYSTEM. THE OCCLUDED FRONT WILL REMAIN OVER THE GULF WHICH MEANS
PRECIP-TYPE WILL REMAIN ALL SNOW WITH THE EXCEPTION OF THE SOUTH TO
EAST SIDE OF KODIAK ISLAND WHICH MAY WARM JUST ENOUGH TO MIX WITH
RAIN BRIEFLY.

MEANWHILE THE LOW CURRENTLY OVER THE SOUTHERN BERING WILL EXIT TO
THE WESTERN BERING WHILE THE NEW LOW OR LOWS APPROACH THE EASTERN
ALEUTIANS AND SOUTHERN ALASKA PENINSULA TONIGHT INTO WEDNESDAY.
THERE IS STILL SOME UNCERTAINTY IN WHETHER THERE WILL BE ONE LOW
OR TWO AND THE EXACT TRACK OF THE SYSTEM. BOTTOM LINE THOUGH...
EXPECT THE END RESULT TO BE A VERY STRONG LOW BOTTOMING OUT IN
THE 940S. WILL ISSUE HIGH WIND WATCHES FOR THE EASTERN ALEUTIANS
AND SOUTHERN ALASKA PENINSULA WITH STORM TO HURRICANE FORCE WINDS
EXPECTED ALONG THE FRONTAL BOUNDARY. THE FRONT WILL BE MOVING AT
A PRETTY GOOD CLIP SO THE STRONGEST WINDS SHOULD NOT LAST FOR MORE
THAN ABOUT 6 HOURS OR SO. THE FRONT WILL HAVE OCCLUDED BY THE TIME
IT REACHES SOUTHWEST ALASKA WEDNESDAY NIGHT SO EXPECT PRECIP TO
BE MAINLY IN THE FORM OF SNOW WHICH WHEN COMBINED WITH THE WINDS
CREATES POTENTIAL FOR BLIZZARD CONDITIONS. WILL WAIT ONE MORE
MODEL CYCLE AND IF THINGS DON'T CHANGE APPRECIABLY WILL LIKELY
ISSUE BLIZZARD WATCHES FOR PORTIONS OF BRISTOL BAY AND THE KUSKOKWIM
DELTA. WITH A SOUTHERLY JET ALOFT THE FRONT WILL MOVE FAIRLY QUICKLY
ACROSS THE SOUTHERN MAINLAND WEDNESDAY NIGHT AND THURSDAY. AT THIS
POINT IN TIME IT DOESN'T LOOK LIKE ANY ADVISORIES OR WARNING WILL
BE NEEDED FOR SOUTHCENTRAL ALASKA...BUT THERE IS STILL LOTS OF TIME
TO WORK OUT THE DETAILS.

.LONG TERM FORECAST...MODELS ARE FAIRLY CONSISTENT IN DEPICTION OF
A LONG-WAVE TROUGH OVER THE BERING AND A RIDGE ALONG SOUTHEAST ALASKA
UP TO NEAR THE ALASKA/CANADA BORDER. A PERSISTENT STRONG UPPER JET
ACROSS THE NORTH PACIFIC AND UP THE WEST SIDE OF THIS RIDGE TOWARD
MAINLAND ALASKA WILL MAINTAIN AN ACTIVE AND FAST MOVING PATTERN.
MODELS DIFFER ON THE MOVEMENT OF INDIVIDUAL SYSTEMS WHICH CAN BE
EXPECTED IN THIS SET-UP.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...HURRICANE FORCE WIND WARNING...155.
         STORM WARNING...150 160 165 170 172 175 176 179 185.
         GALE WARNING...120 130 132 138 171.
         HEAVY FREEZING SPRAY WARNING...180 185.
FIRE WEATHER...NONE.

SEB DEC 11