Small Craft Advisory 795, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
616 AM AKST FRI DEC 21 2012

.SHORT TERM...THE STRONG COLD YUKON HIGH CONTINUES TO DOMINATE
THE WEATHER OVER THE PANHANDLE TODAY. AS A RESULT MOSTLY CLEAR TO
PARTLY CLOUDY SKIES WITH STRONG OUTFLOW WINDS REMAIN THE RULE OF
THE DAY. STRONG WIND GUSTS CONTINUE IN THE USUAL OUTFLOW AREAS OF
THE PASSES EAST OF YAKUTAT, LYNN CANAL, SKAGWAY, AND TAKU INLET.
THOUGH THE WINDS WILL START A GRADUAL DECREASE OVER THE NEXT
24 HOURS AS THE YUKON HIGH GRADUALLY STARTS TO LOSE ITS STRENGTH.
OTHER THEN THAT, THE SYNOPTIC SITUATION WILL NOT CHANGE ALL THAT
MUCH.

 THE MOST PRESSING CONCERN AT THE MOMENT IS THE LOW WIND CHILLS
AND BLOWING SNOW ALONG THE KLONDIKE HIGHWAY. THE BLIZZARD WARNING
THAT WAS UP FOR THE KLONDIKE HIGHWAY WAS ALLOWED TO EXPIRE AT
5 AM THIS MORNING. IT WAS REPLACED BY A WINTER WEATHER ADVISORY
FOR BLOWING SNOW AND LOW WIND CHILLS. THIS WAS DUE TO THE WIND
STARTING TO LOWER AT FRASER CAMP AND THE PRESSURE GRADIENTS
BETWEEN JUNEAU AND SKAGWAY, AND JUNEAU AND WHITEHORSE HAVING
DROPPED NEARLY 5 MB OVERNIGHT AND CONTINUING TO DROP CURRENTLY. I
AM STILL EXPECT AREAS OF BLOWING SNOW AND LOW WIND CHILLS ALONG
THE HIGHWAY BUT I AM ONLY EXPECTING THE VISIBILITY TO BE NEAR A
QUARTER OF A MILE OCCASIONALLY RATHER THAN CONSTANTLY OVER THE
NEXT 24 HOURS AS WINDS GRADUALLY DIMINISH.

 AS FOR JUNEAU, THE TAKU WIND EVENT CONTINUES FOR DOWNTOWN AND
DOUGLAS WITH GUSTS REACHING 55 MPH THIS MORNING AT THE SOUTH
DOUGLAS BOAT HARBOR. A STRONG WIND HEADLINE REMAINS UP INTO LATE
TONIGHT AS CROSS BARRIER FLOW REMAIN HIGH AND THE CRITICAL LEVEL
MIGRATES UPWARD FROM ITS RATHER LOW POSITION LAST NIGHT. BY LATE
TONIGHT WINDS SHOULD START TO DIMINISH AS CROSS BARRIER FLOW
STARTS TO DROP OFF.

 ELSEWHERE IN THE PANHANDLE PARTLY CLOUDY SKIES ARE THE MAIN RULE
WITH THE EXCEPTION OF THE SOUTHERN PANHANDLE. THERE SOME MID TO
HIGH LEVEL CLOUDS ARE SLOWLY MOVING NORTHWARD ASSOCIATED WITH A
WEAK WAVE FROM THE LOW THAT IS NOW WELL SOUTH OF THE AREA. THIS
FEATURE WILL CONTINUE TO WEAKEN AS IT DRIFTS NORTH WITH THE ONLY
IMPACT BEING INCREASED CLOUD COVER OVER THE SOUTHERN AND CENTRAL
PANHANDLE TODAY AND THIS EVENING. OVER THE NORTH THE CLEAR SKIES
WILL ALLOW TEMPERATURES TO PLUMMET TONIGHT IN WIND SHELTERED
AREAS. SINGLE DIGIT AND EVEN BELOW ZERO LOWS ARE NOT OUT OF THE
QUESTION.

 SHORT RANGE MODELS WERE IN GOOD AGREEMENT WITH THE WEATHER
PATTERN NOT CHANGING VERY MUCH OVER THE PERIOD. DECIDED TO STICK
WITH THE NAM FOR THE DETAILS THAT IT PROVIDED FOR THE OUTFLOW
WINDS. FORECAST CONFIDENCE IS ABOVE AVERAGE.

 &&

.LONG TERM /SAT THROUGH WED/...GRADUALLY WARMING TEMPERATURES
LATER IN THE EXTENDED RANGE OTHERWISE CONTINUED COLD ALL AREAS.
HAZARDOUS WIND CONDITIONS NORTHERN AND EASTERN INNER CHANNELS ALSO
EASING UP SUN AND NEXT WEEK. FORECAST CONFIDENCE THAT PATTERN IS
CHANGING IS AT OR ABOVE AVE BUT LESS CERTAIN ABOUT HOW THE DETAILS
WILL SETTLE EARLY TO MID NEXT WEEK. USED NAM MODEL SAT-SUN AND
THEN GFS TO HPC GUIDANCE MON-WED TIME FRAME.

 PATTERN CHANGE FORECAST TO OCCUR SUNDAY TO MONDAY. CURRENT HIGH
AMPLITUDE OMEGA FLOW DISSIPATES AND A WAVY WESTERLY FLOW RETURNS
ACROSS NORTH PACIFIC. SURFACE PRESSURE GRADIENTS SLACKEN FOR
DECREASING WINDS BY SUN BUT HIGH PRESSURE INLAND AND OFFSHORE FLOW
CONTINUES. GRADIENTS BECOME MORE EAST TO WEST AS PRESSURES LOWER
TO THE WEST WITH AN APPROACHING WEATHER SYSTEM. SATELLITE IMAGERY
SHOWS THIS FEATURE JUST GETTING ORGANIZED THIS MORNING UNDER A JET
STREAK NEAR 35N AND 170E. GFS AND ECMWF MODELS HAVE SIMILAR
SOLUTIONS FOR THIS SYSTEM WHICH TAKES IT THROUGH A SPLIT FLOW
WHILE CROSSING DATELINE THEN KEEPS IT WELL SOUTH TOWARD VANCOUVER
ISLAND CHRISTMAS DAY. EC HOWEVER HAS A BIT MORE OF A HANG BACK
SURFACE TROUGH OVER THE EASTERN GULF. LOWS TRACKING SOUTH OF
PANHANDLE USUALLY MEAN DRY WEATHER IN SE AK. ALSO THE ENSEMBLE
ANOMALY GUIDANCE INDICATES NO NOTICEABLE INCREASE IN ATMOS
MOISTURE. MINOR CHANGE TO GRID FORECASTS THIS MORNING WAS TO LOWER
CHC OF SNOW OVER PANHANDLE ON CHRISTMAS. BEST CHANCE WILL BE
SOUTHERN OUTER COAST. THIS FEATURE IS EXPECTED TO DID BOOST SE
WINDS OUTER COASTAL ZONES TUES-WED AS WELL. DID MAINTAIN CHANGE TO
CLOUDY SKIES AND GRADUALLY WARMING DAY AND NIGHT TEMPS ALL AREAS
NEXT WEEK.

 &&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH THIS EVENING FOR AKZ025. STRONG WIND
 	THROUGH SATURDAY MORNING FOR AKZ019. STRONG WIND FROM LATE
	TONIGHT THROUGH SATURDAY MORNING FOR AKZ018. WINTER WEATHER
	ADVISORY UNTIL 5 AM AKST SATURDAY FOR AKZ018. STRONG WIND THROUGH
 	LATE TONIGHT FOR AKZ017.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011>013-031. STORM WARNING
	FOR PKZ012. GALE WARNING FOR PKZ011-013-021-022-031. SMALL CRAFT
	ADVISORY FOR PKZ032>036-041>043-051-053.

&&

EAL/TA