Small Craft Advisory 700, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
311 PM AKST TUE NOV 20 2012

.SHORT TERM...NO CHANGE TO THE SYNOPTIC PATTERN THROUGH THE SHORT
RANGE FORECAST PERIOD. MAIN FEATURES CONTINUE TO BE VERY STRONG AND
COLD HIGH PRESSURE TO THE NORTHEAST AND LOW PRESSURE OVER THE
SOUTHEASTERN GULF. RESULT IS THE SAME AS IT HAS BEEN FOR SEVERAL
DAYS NOW WITH STRONG WIND HEADLINES FOR THE NORTHERN INNER
CHANNELS AND PUBLIC ZONE 25 FOR THE DOWNTOWN JUNEAU AND DOUGLAS
AREA. ALSO HAVE NORTHERLY STORM WARNING IN PLACE FOR NORTHERN LYNN
CANAL. GALES FOR SOUTHERN LYNN, GLACIER BAY, CROSS SOUND, AND
STEPHENS PASSAGE. SMALL CRAFT ADVISORIES ELSEWHERE. ALSO HAVE
FREEZING SPRAY FOR LYNN CANAL, GLACIER BAY, AND STEPHENS PASSAGE.
WINDS IN YAKUTAT BAY MAXING OUT AT 20 KT, BUT GUSTS TO 50 KT OUT
OF DISENCHANTMENT BAY. VERY STRONG NORTHEASTERLY GUSTS FOR THOSE
INNER CHANNELS CLOSEST TO THE COAST MOUNTAINS.

FOR AVIATION INTERESTS, DO NOT HAVE ANY LOW LEVEL WIND SHEAR IN
THE TAFS, BUT LOWER LEVELS ARE CERTAINLY FULL OF LOW LEVEL TURBULENCE
AND THIS HAS BEEN THE MAJOR FEATURE IN THE PIREPS TODAY. JAWS WIND
SENSORS VICINITY JUNEAU AIRPORT CONSISTENTLY REPORTING MODERATE TO
SEVERE TURBULENCE THROUGH THE DAY FOR APPROACHES UP GASTINEAU
CHANNEL. EXPECT THIS WILL CONTINUE THROUGH THE NIGHT.

USED NAM FOR UPDATES TO PRESSURE AND WIND. BLENDED ECMWF, GFS AND
GEM FOR POP AND QPF FIELDS. ADJUSTED TEMPS USING NAM AND GFS.
FORECAST CONFIDENCE IS AVERAGE.

 &&

 .LONG TERM...HUGE CONCERN HERE FOR THE STRENGTH OF A HURRICANE
FORCE LOW MOVING INTO THE SE GULF OFF LANGARA ON THANKSGIVING
MORNING. ALL 20/12Z OPS MODELS KEEP THE LOW CENTER TRACK WEST OF
140W THROUGH 12Z FRI WITH THE DEEPEST AS ECMWF 959 MB. INDICATING
HURRICANE FORCE GUSTS IN PKZ041 AND 042 AND PKZ036 FOR TYPICAL
LINCOLN ROCK HOWLING. NOT ISSUING WATCH BUT WILL GIVE HEADS-UP
CALLS TO FORECASTED AREAS. TWO MITIGATING FACTORS THAT MIGHT KEEP
WIND BELOW 60 MPH: 1) STRONG WARM ADVECTION 2) LOW TRACK W OF
140W. ON THE STRONGER SIDE...850 MB WIND SPEEDS UP TO 80 KT JUST
OFF LANGARA AND 65 KT NEAR PAKT @18Z THU. USED 12Z
AK-GFS-40 THROUGH FRI AND TODAYS HPC GUIDANCE SAT THROUGH TUE.
CONFIDENCE MODERATE ON FORECASTED WIND SPEED AND HIGH ON TRACK OF
LOW.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH LATE TONIGHT FOR AKZ025.
         STRONG WIND THROUGH WEDNESDAY MORNING FOR AKZ019.
         STRONG WIND FROM 6 PM AKST THIS EVENING THROUGH WEDNESDAY
     AFTERNOON FOR AKZ018.
MARINE...STORM WARNING FOR PKZ012.
         GALE WARNING FOR PKZ011-013-022-031-032-035.
         SMALL CRAFT ADVISORY FOR PKZ021-033-034-036-041>043-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ052.

&&

FRITSCH/JC

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JUNEAU AK
344 PM AKST TUE NOV 20 2012

AKZ018>029-210245-
TAIYA INLET AND KLONDIKE HIGHWAY-HAINES BOROUGH AND LYNN CANAL-
GLACIER BAY-EASTERN CHICHAGOF ISLAND-
SALISBURY SOUND TO CAPE FAIRWEATHER COASTAL AREA-
CAPE DECISION TO SALISBURY SOUND COASTAL AREA-
EASTERN BARANOF ISLAND AND SOUTHERN ADMIRALTY ISLAND-
JUNEAU BOROUGH AND NORTHERN ADMIRALTY ISLAND-
INNER CHANNELS FROM KUPREANOF ISLAND TO ETOLIN ISLAND-
DIXON ENTRANCE TO CAPE DECISION COASTAL AREA-
SOUTHERN INNER CHANNELS-MISTY FJORDS-
INCLUDING THE CITIES OF...SKAGWAY...HAINES...GUSTAVUS...HOONAH...
ELFIN COVE...PELICAN...SITKA...PORT ALEXANDER...ANGOON...JUNEAU...
PETERSBURG...WRANGELL...KAKE...CRAIG...KLAWOCK...KETCHIKAN...
METLAKATLA...HYDER
536 AM AKST TUE NOV 20 2012

A DEVELOPING LOW PRESSURE SYSTEM IN THE NORTHEAST PACIFIC WILL
INTENSIFY AS IT MOVES INTO THE SOUTHEAST GULF LATE WEDNESDAY NIGHT
OR EARLY THANKSGIVING DAY. THIS INCOMING LOW WILL PRODUCE STRONG
WINDS AND POTENTIALLY HEAVY PRECIPITATION OVER SOUTHEAST ALASKA
FROM LATE WEDNESDAY NIGHT THROUGH SATURDAY.

AS OF TUESDAY AFTERNOON...THE STORM IS EXPECTED TO MOVE NORTH
ACROSS THE EASTERN GULF AND SLOWLY WEAKEN THERE THROUGH LATE
SATURDAY NIGHT. PERSISTENT HIGH PRESSURE OVER WESTERN CANADA IN
CONJUNCTION WITH LOW PRESSURE OVER THE GULF WILL CONTINUE TO
GENERATE STRONG NORTHEASTERLY OFFSHORE WINDS. WINDS WILL CONTINUE
TO BE STRONGEST OVER THE NORTHERN INNER CHANNELS AND IN THE
VICINITY OF THE COAST MOUNTAINS. AT THE SAME TIME...THE INCOMING
STORM WILL BRING STRONG SOUTHERLY WINDS OVER THE CENTRAL AND
SOUTHERN PANHANDLE. THE ADJACENT COASTAL MARINE AREAS WILL BE
AFFECTED WITH NEAR HURRICANE FORCE FORCE WINDS.

A RELATIVELY WARM AIR MASS WILL ACCOMPANY THE LOW AS IT MOVES
ONSHORE OVER THE PANHANDLE. WITH PERSISTING ARCTIC AIR TO THE
NORTH...POTENTIAL FOR SIGNIFICANT OVER RUNNING AND HEAVY SNOWFALL
CANNOT BE RULED OUT COMPLETELY...ESPECIALLY ACROSS THE CENTRAL
PANHANDLE.