Small Craft Advisory 158, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
438 AM AKDT MON OCT 31 2011

.DISCUSSION...
A DEEP UPPER LOW VORTEX IN THE ARCTIC BASIN WILL BE THE DRIVING
FORCE FOR POTENTIAL HIGH IMPACT WEATHER ALONG THE ARCTIC COAST
TUE-WED.

ALOFT...AT 500 MILLIBARS A VERY DEEP 475 DM LOW NEAR 80N 170W
WILL PINWHEEL AROUND THE NEXT FEW DAYS WITH A SERIES OF SHORTWAVES
TO ROTATE AROUND THE MAIN LOW CENTER. TO THE SOUTH...THERE WILL BE
A MUCH MORE PROGRESSIVE PATTERN IN THE NORTH PAC. AN UPPER LOW IN
THE SOUTHERN BERING SEA MOVES INTO THE NORTHERN GULF OF ALASKA BY
TUE AS ANOTHER LOW NOW SOUTH OF KAMCHATKA MOVES SOUTH OF THE
SOUTHERN ALEUTIANS BY WED. BETWEEN THE LOWS THERE WILL BE SOME MID
LEVEL RIDGING THAT DEVELOPS IN THE SOUTHERN BERING SEA WED.

SURFACE...A TROUGH EXTENDS FROM NEAR BARROW AND TO THE NORTHEAST
INTO THE BEAUFORT SEA.  THIS TROUGH WILL MOVE INTO THE EASTERN
BEAUFORT SEA TONIGHT.  ATTENTION TURNS TO THE NEXT SHORT WAVE THAT
MOVES AROUND THE BACKSIDE OF THE HIGH ARCTIC LOW.  THE MODELS
CONTINUE TO STRUGGLE WITH THIS FEATURE AND DEVELOPMENT OF A POLAR
LOW MON NIGHT. CONDITIONS ARE FAVORABLE FOR THE FORMATION OF A
POLAR LOW ALONG THE LEADING EDGE OF THE ICE PACK IN THE CHUKCHI
SEA. THE MODELS ARE PROBABLY NOT GOING TO HAVE MUCH OF A HANDLE ON
THIS FEATURE UNTIL IT DEVELOPS (IF AT ALL). THE ENERGY RESPONSIBLE FOR
FORMATION IS STILL SEVERAL HUNDRED MILES NORTHWEST OF WRANGEL
ISLAND. AGREE WITH PREVIOUS SHIFTS THAT THERE IS THE POTENTIAL FOR
THIS FEATURE TO BE QUITE STRONG. THAT BEING SAID...THE LATEST RUNS
OF THE MODELS ARE WEAKER WITH THIS FEATURE...SO FOR NOW WILL TAKE
A WAIT AND SEE APPROACH...BUT LEAN TOWARD A STRONGER SOLUTION
WHICH ALSO MAKES THE FORECAST MORE CONSISTENT. IN ALL LIKELIHOOD
WILL NEED TO SEE HOW THE LOW DEVELOPS ON SATELLITE PICTS TO GAIN
THE BEST HANDLE ON THE STRENGTH OF THE LOW. THERE IS ALSO A LOT OF
SPREAD BETWEEN THE ENSEMBLE MEMBERS WITH THE GFS AND ECMWF
ENSEMBLE MEANS WEAKER AND FURTHER NORTH WITH THE LOW. THE GFS IS
ABOUT 8 MILIBARS WEAKER WITH THE LOW THAN THE 00Z RUN LAST NIGHT.

NORTH SLOPE...NO CHANGES PLANNED TO THE BLIZZARD AND COASTAL FLOOD
WATCHES GIVEN THAT THERE IS STILL A LOT OF UNCERTAINTY AS TO WHERE
THE LOW DEVELOPS AND THE EVENTUAL DEPTH OF THE LOW.  RIGHT NOW IT
WOULD APPEAR THAT ANY COASTAL FLOODING THREAT WOULD BE FROM BARROW
SOUTH TO WAINWRIGHT TUE INTO TUE NIGHT.  THE LONG FETCH OF OPEN
WATER OFFSHORE WOULD BE FAVORABLE FOR BUILDING LARGE SEAS OFFSHORE
AND PUSH SOME WATER AND NEAR SHORE ICE ONSHORE. THE LATEST STORM
SURGE MODEL ONLY HAS ABOUT 1 FT OF SURGE...BUT AGAIN THIS IS
BASED ON A WEAK LOW AND THE POTENTIAL FOR A MUCH GREATER STORM
SURGE IS REMAINS IF THE POLAR LOW ENDS UP BEING MUCH DEEPER. THE
GREATEST POTENTIAL FOR BLIZZARD CONDITIONS ALONG THE BEAUFORT SEA
COAST WILL NOT LIKELY COME UNTIL WEDNESDAY AS THE LOW BEGINS TO
PULL AWAY TO THE NORTHEAST AROUND THE MAIN UPPER LOW CENTER.

NOTE...A HIGH SURF ADVISORY WAS ISSUED LATE LAST EVENING FOR THE
NORTHERN ARCTIC COAST AROUND BARROW BASED ON REPORTS OF HIGH SURF
IN THE AREA. CONDITIONS ARE NOT EXPECTED TO GET ANY WORSE
TODAY...AND WILL PROBABLY ACTUALLY IMPROVE SOME. DETEORIATING
CONDITIONS ARE EXPECTED TUESDAY...BUT MUCH WILL DEPEND ON THE
STRENGTH AND POSITION OF THE POLAR LOW THAT IS EXPECTED TO BEGIN
DEVELOPING TONIGHT.

INTERIOR...COLDER WEATHER EARLY THIS WEEK IN THE WAKE OF AN UPPER
TROUGH AND COLD FRONT THAT WORKED ACROSS THE INTERIOR YESTERDAY.
CLOUDS AND A FEW FLURRIES LINGERING IN PARTS OF THE INTERIOR WITH
SPME BREAKS IN THE CLOUDS IN SOME AREAS THE NEXT COUPLE OF DAYS.
A SFC LOW IS EXPECTED TO RAPIDLY DEEPEN IN THE GULF OF ALASKA TUE
AND MOVE TO NEAR YAKUTAT TUE EVENING. THIS WILL PRODUCE SOME
OVERRUNNING SNOW INTO THE SOUTHEAST INTERIOR TUE INTO TUE NIGHT
WITH THE POTENTIAL FOR A FEW INCHES OF SNOW IN THE UPPER TANANA
VALLEY...AND POSSIBLY 6 INCHES OR MORE OF SNOW IN PARTS OF THE
EASTERN ALASKA RANGE. POSSIBLE THAT AN ADVISORY WILL BE NEEDED FOR
AT LEAST ZONE 226 DOWN THE ROAD.

WEST COAST...MOST OF THE WEST COAST WILL BE EITHER SOUTH OF THE
POLAR LOW OR NORTH OF THE BERING SEA LOW.  POTENTIAL FOR SOME HIGH
SURF LATE TUE INTO TUE EVENING ALONG THE CHUKCHI SEA INTO THE
KOTZEBUE SOUND...BUT IT DEPENDS ON THE DEPTH/LOCATION OF THE POLAR
LOW.  SOME SNOW SHOWERS EXPECTED...MAINLY ALONG THE WESTERN CAPES.
SNOW AND WIND POSSIBLE IN SOUTHWEST ALASKA BY THURSDAY AS THE NEXT
THE BERING SEA LOW MOVES EAST.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...CONDITIONS WILL IMPROVE
ALONG THE WESTERN AND NORTHERN ARCTIC COAST WEDNESDAY AS THE
WINDS AND SEAS BEGIN TO DIMINISH...BUT WILL LIKELY REMAIN ROUGH
THROUGH WEDNESDAY EVENING ALONG THE BEAUFORT SEA COAST. LOW
PRESSURE IN THE BERING SEA MAY BRING ELY GALES TO THE SAINT
LAWRENCE WATERS AND NORTON SOUND ON THURSDAY.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WATCH FOR AKZ201-AKZ202-AKZ203-AKZ204.

HIGH SURF ADVISORY FOR AKZ202.

COASTAL FLOOD WATCH FOR AKZ201-AKZ202.

HEAVY FREEZING SPRAY WARNING FOR PKZ225-PKZ230.

SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225-PKZ230.

GALE WARNING FOR PKZ225-PKZ230.

BRISK WIND ADVISORY FOR PKZ240-PKZ245.
&&

CB OCT 11