Small Craft Advisory 709, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
315 PM AKST SAT NOV 24 2012

.SHORT TERM...THE REMAINS OF THE LOW ARE DISSIPATING AS IT
TRACKS TO THE EAST ALONG SUMNER STRAIT. THE LOW WILL REDEVELOP
ABOUT ABOUT 100 NM NE OF KETCHIKAN 12Z SUN AND DRIFT AWAY TO THE
EAST. THIS LOW TRACK HELPS IDENTIFY THE PATTERNS OF PRECIPITATION
TYPE AND WINDS. THE NORTH WINDS NORTH OF SUMNER STRAIT IS
THE NORTHERN EDGE OF THE RAIN.

THE WINDS ARE DIMINISHING THIS EVENING AS THE LOW DISSIPATES.
THE OUTFLOW OF ARCTIC AIR FROM YUKON TERRITORY WILL ALSO WEAKEN
OVERNIGHT WITH SOME STRENGTHENING SUNDAY. - JBT

.LONG TERM...
PATTERN STARTS OUT WITH NEARLY A REX-SHAPED BLOCK ALONG 160-170W
WITH AN UPPER RIDGE ALONG 145W AND A WEAK SHORTWAVE OVER THE
PANHANDLE. BY SUN EVENING SE ALASKA IS UNDER AN UPPER RIDGE TO WITH
SHORTWAVES DROPPING IN FROM THE NW THAT RESULTS IN SOMEWHAT
WESTERLY FLOW ALOFT...BUT WITH MODERATE ARCTIC HIGH PRESSURE OVER
THE YUKON AT THE SURFACE. 23/12 OPS MODELS ALL AGREE ON THIS
FEATURE BECOMING DOMINANT INTO WED FOR OUTFLOW WIND DRYING AND
COOLER TEMPS. BY MIDDAY TUE SOME VERY COLD AIR ALOFT THAT WAS NEAR
42N 160W OR SO TODAY WILL BE TRYING TO UNDERCUT THIS PATTERN AND
MOVE EASTWARD. THIS SETS UP A WEST COAST TYPE RIDGE TUE AS A MAJOR
UPPER LOW GRADUALLY MOVES EAST TO HUDSON BAY.

SO BY WED WE START SEEING SOME INCREASING MOISTURE FROM THE SE
ALOFT WHICH IS ALWAYS A BIT DICEY TO PEG FOR PRECIPITATION. IT WAS
EASY TO SELECT THE HPC GUIDANCE FOR WED AND BEYOND DUE TO THE
ENSEMBLE MIX BY HPC FOR THE LONGER AND BLURRY RANGE. OUR OLD FRIEND
ARCTIC HIGH PRESSURE WILL HANG OUT TO THE NORTH AND EAST OF THE
PANHANDLE AS SOME SORT OF STORM SYSTEM SHOWS ITSELF ON THU WELL SE
OF DIXON ENTRANCE. FORECASTED COOL AND WINDY WITH SOME CHANGE OF
PRECIP MAINLY SNOW NORTH BUT WHO COULD BE CONFIDENT WITH A STORM
TRACK THAT FAR OUT UNDER THIS MESS? METHINKS GIVE IT A DAY OR TWO
BEFORE A STRONG SIGNAL EMERGES. CONFIDENCE ONLY MODERATE IN THE
MEDIUM AND A BIG GUESS SUPPORTED BY HPC IN THE LONGER RANGE. -JC

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 3 PM AKST THIS AFTERNOON FOR AKZ019.
         STRONG WIND UNTIL 1 AM AKST SUNDAY FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-013-036.
         SMALL CRAFT ADVISORY FOR PKZ011-022-031>035-041-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051-052.
&&