Small Craft Advisory 765, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
605 AM AKST THU DEC 13 2012

.SHORT TERM...984 MB SFC LOW CENTERED JUST NE OF WHITEHORSE AT 6
AM. OCCLUDED FRONT EXTENDS SOUTH FROM THIS LOW ALONG THE COASTAL
MTNS TO MISTY FJORDS AND HAIDA GWAII. WEST WIND GRADIENT
SPREADING INLAND BEHIND FRONT. NW WIND DOWN CLARENCE STRAIT TO
LINCOLN ROCK BUT NO WIND SWITCH AT KETCHIKAN YET...SHOULD BE SOON.
PRECIP TOTALS OVERNIGHT WERE QUITE VARIED GENERALLY BETWEEN 0.25
AND 0.75 INCHES BUT HOONAH RAWS SOUTH OF TOWN MEASURED 1.00 INCH.
PRECIP TYPE WAS RAIN MOST AREAS BUT SNOW DID CONTINUE OUT THE
ROAD FROM HAINES AND IN PETERSBURG OVERNIGHT. WINTER WEATHER
ADVISORIES FOR THESE TWO AREAS WILL EXPIRE AT 6AM.

COOL AIR ADVECTION IN STORE TODAY ALL PANHANDLE. THIS WILL LIKELY
TRIGGER A FEW RAIN AND SNOW SHOWERS DURING THE DAY. THE ONSHORE
FLOW WILL KEEP TEMPS ABV FREEZING MOST AREAS. SNOW LEVEL IS
BETWEEN 1K- 2K FEET MSL IN THE NORTHERN PANHANDLE BASED ON YAK
SOUNDING AND JNU PROFILER DATA. SNOW LEVEL 3K PER ANNETTE
SOUNDING. BUT SOUNDINGS SHOW COOLING TREND ALOFT SO SNOW LEVELS
SHOULD BE LOWERING A BIT DURING THE DAY. BIORKA RADAR INDICATING
FAST MOVING SHOWERS SWEEPING IN WEST TO EAST. GALES ARE UP FOR
LYNN CANAL...CROSS SOUND WHICH HAS BEEN GUSTING TO 60 KT...AND
OUTER COAST NORTH OF CAPE FAIRWEATHER.

USED NAM MODEL SOLUTIONS FOR SFC PRESSURE PATTERN TODAY AND THEN GFS
AND SREF ENSEMBLE FOR TONIGHT. THIS MATCHED UP WITH WFO ANC TIMING
OF NEXT FRONTAL SYSTEM APPROACHING FROM WEST. MAIN IMPACTS WILL BE
FELT FRI WHICH IS BEYOND THE SHORT TERM PERIOD. THU WILL BE
CHARACTERIZED AS UNSTABLE WITH COOL AIR INCREASING ALOFT. THEN
BRIEF STABILIZATION TONIGHT WITH TRANSITION TO PREFRONTAL WEATHER.
STRONG LOW LEVEL WEST WINDS WILL GRADUALLY DIMINISH AND BACK TO
S-SE TONIGHT. PRECIP WILL START AS SNOW IN YAKUTAT OVERNIGHT AND
COULD REACH GLACIER BAY AND JUNEAU BY DAY BREAK FRI.

&&

.LONG TERM / FRIDAY TO WEDNESDAY / ...THE DEVELOPING LOW MOVES
ACROSS THE GULF OF ALASKA. THE ASSOCIATED FRONTAL BAND THE
PRECIPITATION WITH IT WILL BE SPREADING ACROSS THE PANHANDLE ON
FRIDAY. COLDER AIR SPREADING BACK ACROSS THE GULF AROUND THE SURFACE
BY SATURDAY AROUND THE WEAKENING RESIDUAL LOW IN THE NORTHERN
GULF. THE LOW AND INVERTED THROUGH PERSISTING THROUGH THE WEEKEND.
THE LONG RANGE MODEL SOLUTIONS INDICATE A STRONG LOW MOVING ALONG
THE ALEUTIANS AND THEN TO THE WESTERN GULF BY EARLY NEXT WEEK THEN
SOUTHEAST.

FRIDAYS FRONT LOOKS TO BRING IN A BAND OF GALE FORCE WINDS ACROSS
THE OUTER COAST WATERS AND POSSIBLY INTO THE INNER CHANNEL WATERS.
ON THE SOUTH SIDE OF THE RESIDUAL LOW IN NORTHERN GULF A LARGE
BAND OF WESTERLY SMALL CRAFT TO MIN GALE FORCE WINDS THAT WILL BE
DEVELOPING A FOLLOWING SWELL FOR THE EARLY PART OF TO THE WEEK.

THE FAST FLOW ALOFT HAS SYSTEMS SPREADING ACROSS THE REGION AT A
QUICK PACE WHICH MEANS THAT THEIR IS STRENGTH AND TIMING ISSUES
FOR THE LOWS MOVING THROUGH THE REGION. CONFIDENCE IS MODERATE TO
THE WEEKEND AND LOW FOR THE EARLY PART OF NEXT WEEK BECAUSE OF THE
DIFFERENCES IN THE MODEL SOLUTIONS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 6 AM AKST EARLY THIS MORNING FOR
     AKZ019-026.
         STRONG WIND UNTIL 9 AM AKST THIS MORNING FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-013-022-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-021-032-033-036-041-042-053.

&&

TA/BEZENEK