Small Craft Advisory 723, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
353 PM AKST TUE NOV 27 2012

.SHORT TERM...HIGH PRESSURE OVER THE YUKON IS RIDGING TOT HE
SOUTHEAST INTO BRITISH COLUMBIA. A LOW IN THE NORTHERN PACIFIC
REMAINS NEARLY STATIONARY. THE NORTHEASTERLY PRESSURE GRADIENT
OVER SOUTHEAST ALASKA IS GETTING LARGER.

MAIN FOCUS FOR THE SHORT TERM FORECAST PERIOD HAS BEEN A HIGH
WIND WARNING FOR THE JUNEAU AREA AND REFINING THE WIND FORECAST.
PRESSURE GRADIENT WILL BE STRONGEST OVER THE FAR NORTHERN INNER
CHANNELS AND WILL BE AFFECTED BY SHORT WAVES THAT ARE ROTATING
AROUND THE NORTH PACIFIC LOW. BELIEVE THERE WILL BE A BIT OF A
RELAXATION IN WINDS OVER DOWNTOWN JUNEAU AND DOUGLAS WEDNESDAY
DURING THE DAY AS ONE OF THESE SHORT WAVES PULLS AWAY FROM THE
COAST, BUT THEN WILL RAMP BACK UP AGAIN AS ANOTHER SHORT WAVE
ROTATES INTO SOUTHEAST ALASKA FROM THE SOUTH LATE IN THE DAY
WEDNESDAY. NEITHER THE LOW NOR THE HIGH OVER WESTERN CANADA ARE
FORECAST TO GO ANYWHERE OR CHANGE MUCH IN INTENSITY FOR THE FIRST
PART OF THE EXTENDED RANGE FORECAST PERIOD. AS A RESULT AND IN
COORDINATION WITH THE LONG RANGE FORECASTER, HAVE EXTENDED THE
HIGH WIND WARNING OUT UNTIL THURSDAY MORNING. ELSEWHERE WIND WISE,
HAVE STRONG WIND HEADLINES FOR BOTH SKAGWAY AND HAINES. STRONG
WINDS OVER ZONE 17 AS WELL BUT EXPECT THEM TO BE EAST OF YAKUTAT
AND OF LITTLE TO NO IMPACT ON LOCAL POPULATION.

WINDS OVER THE NORTHERN INNER CHANNELS NORTH OF JUNEAU STILL
FORECAST TO GET UP TO 60 KT OVER NORTHERN LYNN AND 50 KT OVER
SOUTHERN LYNN THROUGH WEDNESDAY AFTERNOON AND HAVE HEAVY FREEZING
SPRAY IN NORTHERN LYNN. GALES OR SMALL CRAFT ADVISORIES ELSEWHERE.

MODELS CONTINUE TO ADVERTISE TEMPS SIGNIFICANTLY COLDER THAN IN
GRIDS AND HAVE TRENDED THIS DIRECTION DUE TO THE AMOUNT OF VERY
COLD ARCTIC AIR EXPECTED TO PENETRATE INTO THE PANHANDLE FROM THE
CANADIAN SIDE OF THE COAST MOUNTAINS. POP ASSOCIATED WITH AN
OCCLUDED FRONT EXPECTED TO GET ABOUT HALF WAY UP THE PANHANDLE BY
THE END OF THE SHORT RANGE FORECAST PERIOD. THINK THE SNOW LINE
WILL BE SOMEWHERE OVER ZONE 26, SO THERE IS SOME SNOW IN THE
FORECAST WITH UP TO 2 INCHES POSSIBLE BETWEEN ANGOON AND SUMNER
STRAIT ANT 3 TO 4 INCHES NEAR HYDER OVER THE NEXT 24 HRS.

USED NAM FOR ADJUSTMENT TO WINDS OVER THE GULF. BLENDED GEM AND
ECMWF FOR POP AND QPF. ADJUSTED TEMPS WITH NAM AND GFS. SNOW
LEVELS STRAIGHT GFS40. FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...NO SIGNIFICANT CHANGE IN THE FORECAST THINKING WITH
THE VERTICALLY STACKED LOW PRESSURE SYSTEM OVER THE SOUTHERN GULF
THAT WILL CONTINUE TO ROTATE SMALL WAVES NORTH INTO SOUTHERN HALF
OF THE PANHANDLE. GENERAL HIGH PRESSURE WILL CONTINUE OVER THE
ALASKAN INTERIOR TO NORTHWEST CANADA. THIS IS RESULTING IN GUSTY
OUTFLOW WINDS. WITH SUSTAINED FLOW AND LITTLE CHANGE IN
VELOCITIES... WILL GO WITH MORE FULLY DEVELOPED SEA STATE FOR SOME
OF THE MARINE CHANNELS.

THE HIGH WIND EVENT GOING ON IN JUNEAU WAS EXTENDED THROUGH
WEDNESDAY NIGHT AS THE STRONG WINDS ACROSS THE RIDGE TOPS IN THE
JUNEAU AREA WILL MAINTAIN THE TAKU MOUNTAIN WAVE THROUGH THAT TIME
FRAME. RIGHT NOW STILL JUST CALL FOR GUSTS TO 60... BUT WOULD NOT
BE SURPRISED TO SEE HIGHER VALUES BEING REPORTED.

EARLY MODIFICATIONS TO THE FORECAST THROUGH ABOUT 00Z SATURDAY WERE
WITH NAM AND OR ECMWF WHILE LITTLE IN WAY OF CHANGES WERE MADE TO
LATER PERIODS OF THE FORECAST PACKAGE.

FORECAST CONFIDENCE IF GOOD THROUGH FRIDAY AFTERNOON AND LOWERS TO
AVERAGE FOR WEEKEND INTO EARLY NEXT WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING UNTIL 6 AM AKST THURSDAY FOR AKZ025.
         STRONG WIND THROUGH WEDNESDAY AFTERNOON FOR AKZ018-019.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         STORM WARNING FOR PKZ012-013.
         GALE WARNING FOR PKZ011-021-022-031-032-035-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ033-034-036-053.

&&

FRITSCH/BEZENEK