Wind Advisory 87, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
608 AM AKST SUN NOV 28 2010

.SHORT TERM...COMPLEX PATTERN EVOLVING THAT WILL CAUSE TWO
NOTEWORTHY EVENTS. BROAD AREA OF SNOW NORTH OF CAPE SPENCER TO
JUNEAU LINE TODAY AND A HIGH WIND EVENT SOUTHERN COAST AND
SOUTHERN INNER CHANNELS MONDAY. HIGHER CONFIDENCE WITH WIND
EVENT. SNOW EVENT LIKELY BUT AMOUNTS BASED ON SNOW PERSISTING AND NOT
CHANGING TO RAIN TOO SOON.

1003 MB SFC LOW JUST S OF PRINCE WM SOUND AT 14Z HAS BEEN
GRADUALLY DEEPENING OVERNIGHT THANKS TO DIGGING COLD TROUGH OVER
WRN AK. MOISTURE STREAMING EAST AHEAD OF LOW ALONG AN W-E FRONTAL
BOUNDARY IS CAUSING SNOW FROM YAKUTAT TO SKAGWAY AND NRN GLACIER
BAY AND JUNEAU. SNOW ADVISORY FOR YAKUTAT ZONE WAS CONTINUED TO 3
PM SUN BUT SNOW COULD END BEFORE THAT. THE FRONTAL BOUNDARY MAY
BUMP JUST NORTH OF YAK THIS MORNING ALLOWING WARMER AIR TO SPREAD
INLAND BY 18Z BASED ON 1000-850 MB THICKNESS PROGS...A BIT SOONER
THAN CURRENTLY FCST. PRECIP MAY TAPER OFF BRIEFLY TODAY BEFORE
SURGE OF WARM PRECIP PUSHES INTO NE GULF COAST OVERNIGHT TONIGHT.

SNOW ADVISORIES WERE ISSUED FOR SKAGWAY AND HAINES ZONES FOR
TODAY AND TONIGHT...AND FOR JUNEAU ZONE THROUGH 6 PM TODAY.
BELIEVE A BURST OF SNOW IS POSSIBLE ACROSS THESE NRN INNER CHANNEL
ZONES FROM LATE THIS MORNING THROUGH LATE AFTERNOON THAT COULD
PRODUCE 3 TO 6 INCHES OF SNOW. SNOW WILL PERSIST OVERNIGHT OVER
HAINES AND SKAGWAY HIGHWAY PASSES AND THIS COORDINATED WITH
ENVIRONMENT CANADA FORECASTERS. BUFKIT TOOL HIGHLIGHTS SNOWFALL
RATES IN JUNEAU AREA HIGHEST FROM 18Z SUN TO 03Z MON WHICH ALIGNS
WITH GFS MODEL FCST OF UPPER LEVEL DIFFLUENCE AND ASSOC ENHANCED
UPWARD MOTION.

TRICKY FCST FOR OVERNIGHT TONIGHT. ALL MODELS FCST THE NRN GULF
GULF LOW CENTER WILL STALL JUST WEST OF YAKUTAT SUN EVENING AND
MERGE WITH STORM FORCE 996 MB LOW CURRENTLY AT 50N SOUTH OF
KODIAK. HOWEVER MODELS ARE STRUGGLE TO CAPTURE DETAILS WITH THE
DOUBLE LOW CENTER STRUCTURE OVER WEST GULF. THEY SHOW AN ELONGATED
SFC TROUGH ARCHING NE FROM 50N TOWARD THE LOW APPROACHING YAKUTAT
BUT ONLY HINT AT THE DETAILS ASSOC WITH A COMMA CLOUD CENTERED
NEAR 53N 141W MOVING E AT 35 KTS. THE DEPICTED LOW IS SHOWN BY ALL
MODELS TO DEEPEN QUITE A BIT TODAY AND CURVE TOWARD DIXON ENTRANCE
AND SRN SE AK COAST BY MON MORNING. DETAILS WITH THIS POTENTIAL
HIGH WIND MAKER DISCUSSED BELOW.

&&

.LONG TERM...DEVELOPING WAVE IN THE UPPER LEVEL FLOW WILL CURVE A
SURFACE LOW NORTH ALONG THE OUTER COAST OF THE PANHANDLE MONDAY WHICH
WILL DUMBBELL ABOUT A LOW IN THE NORTHERN GULF BEFORE CURVING BACK
AROUND TO THE SOUTHEAST AND INTO BRITISH COLUMBIA THE ASSOCIATED
FRONTAL WILL HAVE DEVELOPED A STRONG BAND OF WINDS WITH THE FRONT.
STRONGEST WINDS WILL IMPACT SOUTHEAST ALASKA MONDAY MORNING. HAVE
STORM FORCE WINDS FOR PKZ041>043 AND A PORTION OF 51 TOO. STORM FORCE
MAY TRY TO WORK INTO CLARENCE STRAIT AS WELL BUT HAVE NOT PUT THEM
IN AT THE MOMENT. WINDS ARE LOOKING EVEN STRONGER THROUGH HECATE
STRAIT AND DIXON ENTRANCE IN THE CANADIAN WATERS. BELIEVE THAT
THERE IS A HIGH LIKELIHOOD OF WARNING LEVEL GUSTS FOR AKZ027 AND
028...AND SOUTHERN 023 ON MONDAY MORNING...ADDED A 'BUFFER ZONE'
OF ZONES 22/26/29 THAT SHOULD SEE ADVISORY GUSTS MONDAY AS WELL...
FOR THESE AREAS HAVE ISSUED A HIGH WIND WATCH FOR THE DAY PERIOD
OF MONDAY...(ADVY) GUSTS WILL HOWEVER LIKELY PERSIST INTO MONDAY
NIGHT. OVER THE NORTHERN ZONES EXPECT A GOOD NORTHERLY OUTFLOW
FROM INTERIOR PASSES AND THROUGH LYNN CANAL BUT LACKING A
SIGNIFICANT HIGH LOCALIZED IN THE YUKON AND NORTHERN BC FOR VERY
STRONG WINDS. SHOULD SEE A TEMPERATURE COOL DOWN THROUGH MID WEEK
HOWEVER...ESPECIALLY OF THE NORTHERN PORTION.

LATER PORTION OF THE FORECAST WAS PERUSED AND JUDGED TO BE GOOD
ENOUGH FOR NOW...AS WAS TRYING TO CONCENTRATE ON WIND AND
POTENTIALLY A SNOW ISSUE OVER THE FORECAST AREA.

TEMPERATURE PROFILES OVER THE NORTH WILL BE A MAJOR ISSUE ON
WHETHER THERE WILL A SIGNIFICANT SNOWFALL OR WILL BE A MISH MASH
OF WET SNOW AND RAIN. FOR THE TIME BEING DID NOT DEAL WITH A MAJOR
WARM UP BUT TRIED TO REFRAIN FROM A MAJOR SNOW ISSUE TOO.

FORECAST ADJUSTMENTS WERE WITH THE NAM AND ECMWF INTO WEDNESDAY.
CONFIDENCE IN THE FORECAST IS ABOVE AVERAGE TO TUESDAY AND THEN
LOWERING TO THE END OF THE WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH FROM LATE TONIGHT THROUGH MONDAY AFTERNOON FOR
     AKZ022-023-026>029.
         WINTER WEATHER ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ025.
         WINTER WEATHER ADVISORY UNTIL 3 AM AKST MONDAY FOR AKZ018-019.
         WINTER WEATHER ADVISORY UNTIL 3 PM AKST THIS AFTERNOON FOR
     AKZ017.
MARINE...GALE WARNING FOR PKZ022-033-035-036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031-032-034-051-052.

&&

TA/BEZENEK