Small Craft Advisory 129, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
339 PM AKST FRI FEB 7 2014

.SHORT TERM...COLD AND LOCALLY WINDY FORECAST ACROSS THE
PANHANDLE IS THE MAIN WEATHER HEADLINE TODAY. OVERNIGHT LOW TEMPS
GOT DOWN INTO THE LOW TEENS TO SINGLE DIGITS IN MANY PLACES WITH
A FEW AREAS IN THE NORTH FLIRTING WITH ZERO. ONE OF THE FEW
PLACES THAT DIDN'T GET THAT COLD WAS YAKUTAT BUT THAT WAS BECAUSE
THEY HAD CLOUD COVER AND SOME LIGHT SNOW TO DEAL WITH OVER NIGHT
FROM THE LOW THAT DEVELOPED IN THE NW GULF YESTERDAY EVENING.
SNOW ACCUMULATION ONLY AMOUNTED TO AROUND AN INCH THERE
OVERNIGHT. IT HAS SINCE STOPPED AND THE CLOUDS ARE STARTING TO
BREAK UP. AS FOR THE WINDS, SKAGWAY AND LYNN CANAL HAVE HAD
INCREASING WINDS ALL MORNING AS THE YUKON HIGH BUILDS UP. SKAGWAY
HAS SEEN WINDS AS HIGH AS 50 MPH WHILE ELDRED ROCK HAS BUILT UP
TO GALE FORCE THIS AFTERNOON.

INTO SATURDAY, THE SITUATION IS NOT GOING TO CHANGE ALL THAT
MUCH. THE NORTHERLY PRESSURE GRADIENT WILL NOT CHANGE ASIDE FROM
IT SPREADING INTO THE NORTHERN PANHANDLE A BIT MORE AS MORE ARCTIC
AIR FLOWS IN. OTHERWISE THE YUKON HIGH WILL BE BUILDING AT ABOUT
THE SAME RATE AS THE NW GULF LOW PULLS AWAY. AS SUCH GALE FORCE
WINDS ARE EXPECTED TO CONTINUE IN LYNN CANAL WITH STRONG WIND
GUSTS IN SKAGWAY. TAKU INLET WILL ALSO SEE SOME GUSTY WINDS WHILE
CROSS SOUND AND STEPHENS PASSAGE WILL SEE SOME SMALL CRAFT WINDS
THROUGH THE NEXT 24 HOURS AS WELL. MOST OF THE REST OF THE
PANHANDLE WILL SEE WINDS LESS THEN 20 KT.

THE SITUATION FOR TAKU WINDS THROUGH THE NEXT 24 HOURS IS NOT
THAT GREAT. WHILE THERE IS AN INVERSION BUILDING UP, THE CRITICAL
LEVEL IS A BIT TOO LOW AROUND 700 MB RATHER THEN THE OPTIMUM 500
MB. ALSO THE CROSS BARRIER FLOW IS ONLY AROUND 10 TO 15 KT RIGHT
NOW AND IS NOT EXPECTED TO GET MUCH HIGHER THROUGH SAT AFTERNOON.
SO AT MOST ONLY EXPECTING POSSIBLY 20 TO 25 KT GUSTS AROUND
DOWNTOWN JUNEAU AND SOUTH DOUGLAS MOSTLY ON SAT.

THE REST OF THE FORECAST CAN BASICALLY BE DESCRIBED WITH FIVE
WORDS: DRY, COLD, AND MOSTLY CLEAR. OVERNIGHT LOWS WILL AGAIN DROP
INTO THE TEENS MAYBE SINGLE DIGITS AS SKIES REMAIN MOSTLY CLEAR
OVER MOST OF THE AREA. AREAS THAT ARE WIND SHELTERED HAVE THE BEST
CHANCE OF SEEING THESE REALLY LOW TEMPS. AREAS THAT HAVE A LITTLE
WIND WILL NOT BE QUITE AS COLD AS LAST NIGHT AS THE BIT OF WIND
PROVIDES ENOUGH MIXING TO BREAK UP THE INVERSION. HIGHS TOMORROW
WILL REBOUND AGAIN INTO THE 20S AND LOW 30S.

SHORT RANGE MODELS WERE IN DECENT AGREEMENT THROUGH THE NEXT 24
HOURS HOWEVER THEY WERE CONSISTENTLY PUTTING TOO MUCH OF THE
NORTHERLY PRESSURE GRADIENT ON THIS SIDE OF THE COAST MOUNTAINS
WHILE REALITY STILL HAS MOST OF THAT GRADIENT NORTH OF SKAGWAY.
GENERALLY DID LOCAL CHANGES WHERE NEEDED BUT USED ECMWF AND NAM
FOR ANY OVERALL CHANGES.

.LONG TERM...GENERAL THINKING IN THE LONG TERM REMAINS THE SAME
BUT MODELS CONTINUE TO STRUGGLE WITH CHANGE TO A MORE ACTIVE
WEATHER PATTERN NEXT WEEK. THE BLOCKING PATTERN WITH THE HIGH OVER
THE NORTH PACIFIC AND INTO THE BERING SEA WILL BEGIN TO BREAKDOWN
WITH A LARGE SCALE TROUGH SETTING UP OVER MUCH OF THE STATE AND
INTO THE GULF NEXT WEEK. THIS WILL LEAD TO INCREASED CHANCES OF
PRECIPITATION OVER SOUTHEAST ALASKA. HOWEVER, DETAILS ARE FAR FROM
BEING PINNED DOWN AT THIS POINT AS MODELS CONTINUE TO FLIP FLOP
WITH EACH MODEL RUN. THEREFORE, LIMITED CHANGES TO ONGOING
FORECAST UNTIL THERE IS BETTER MODEL CONSENSUS.

OUTFLOW WINDS STRENGTHEN LATER SATURDAY AND INTO EARLY NEXT WEEK
AS MULTIPLE LOW PRESSURE SYSTEMS TRACK JUST SOUTH OF THE
PANHANDLE. THE NORTHEASTERLY WINDS WILL PICK UP TO GALE FORCE
OVER THE NORTHERN AND CENTRAL INNER CHANNELS. WITH ARCTIC AIR
STILL IN PLACE WILL SEE AREAS OF FREEZING SPRAY. THERE IS THE
POTENTIAL FOR A TAKU WIND EVENT BEGINNING LATE SUNDAY NIGHT AND
CONTINUING THROUGH MONDAY AS CROSS BARRIER FLOW INCREASES TO 50-55
KTS AND A STRONG INVERSION EXISTS. THE CRITICAL LEVEL IS PROGGED
TO BE A BIT BELOW THE PRIME REGION OF 500 MB, BUT WOULD STILL BE
SUFFICIENT TO PRODUCE STRONG WIND GUSTS. A STRONG WIND HEADLINE
WILL LIKELY BE NEEDED IN LATER SHIFTS AND A SLIGHTLY HIGHER
CRITICAL LEVEL COULD WARRANT THE CONSIDERATION OF A HIGH WIND
WATCH FOR GUSTS OVER 60 MPH.

LATEST GUIDANCE SUGGEST PRECIPITATION WITH THE INITIAL SYSTEM
ON MONDAY WILL REMAIN MAINLY OVER THE SOUTHERN HALF OF THE
PANHANDLE SO LIMITED PRECIPITATION CHANCES ACROSS THE NORTH. SNOW
IS EXPECTED TO BE THE PRECIPITATION TYPE ACROSS THE SOUTH WITH
SOME AREAS REACHING NEAR ADVISORY CRITERIA OF 3-4 INCHES IN 12
HOURS MONDAY. FOR THE REMAINDER OF THE WEEK, CHANCE TO LIKELY
PRECIPITATION CHANCES WERE KEPT IN THE FORECAST WITH LITTLE MODEL
AGREEMENT. IT DOES APPEAR THAT TEMPERATURES WILL BE GRADUALLY
WARMING THROUGH THE WEEK WITH RAIN BEGINNING TO MIX IN BY MID WEEK
ACROSS THE SOUTHERN AREAS.

USED THE 12Z ECMWF FOR UPDATES FOR THE FORECAST THROUGH DAY 4
BEFORE TRANSITIONING TO THE NEW WPC GUIDANCE. FORECASTER
CONFIDENCE DECREASES THROUGH NEXT WEEK AS MODELS CONTINUE TO
STRUGGLE WITH CHANGE TO A MORE UNSETTLED WEATHER PATTERN.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH SATURDAY AFTERNOON FOR AKZ018.
         WIND CHILL ADVISORY UNTIL 9 AM AKST SATURDAY FOR AKZ018.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031-051-052.

&&

EAL/TPS