Small Craft Advisory 17, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
324 PM AKST THU JAN 5 2012

.SHORT TERM...SHORT LIVED BREAK IN CLOUD COVER THIS EVENING WILL
PERMIT SOME PATCHY FOG ESPECIALLY IN THE CENTRAL PANHANDLE.  THE
BREAK IN CLOUD COVER WILL BE ENDED BY A LARGE-SCALE GALE FORCE
SYSTEM THAT WILL APPROACH THE OUTER COAST TONIGHT AND GENERATE A
HEAVY SNOW EVENT FOR THE YAKUTAT ZONE. PLEASE NOTE THE WINTER
STORM WARNING. STRONG WARM ADVECTION AHEAD OF THE  GALE-FORCE
SYSTEM WILL BEGIN ABOUT 12Z SAT.

 HIGHLY PROGRESSIVE AND ACTIVE PATTERN CONTINUES. CONFIDENCE IN
THE SHORT RANGE PACKAGE IS AVERAGE. THE EUROPEAN MODEL RUN AT
05.12 WAS THE EASIEST TO RECONCILE WITH INITIAL CONDITIONS OF THE
 LARGE-SCALE SYSTEM DISCUSSED IN THE PARAGRAPH IMMEDIATELY BELOW.

 985 MB LOW 600 NM S OF PAMD IS TRACKING NE WITH ASSOCD OCFNT ABT
600 NM SW OF THE PNHDL. THIS SYSTEM HAS AN ASSOCD HIGH PRESSURE
RIDGE ALOFT THAT IS MOVING FROM THE ERN GLFALSK TO THE PNHDL AND
WILL RAPIDLY MOVE E BYD THE COAST MTN RANGE BY 12Z. THE OCFNT
WILL MOVE ONSHORE THE OUTER COAST ABOUT 21Z SAT. FOR THE
REMAINDER OF THE LIFE CYCLE OF THIS SYSTEM PLEASE SEE THE LONG
RANGE SECTION BELOW.

.LONG TERM...MODELS IN DECENT AGREEMENT ON THE LONGER RANGE THRU
EARLY NEXT WEEK...WITH FAIRLY SMALL DIFFERENCES AT MOST. A
WEAKENING OCCLUDED FRONT WILL MOVE THRU SE AK FRI EVENING.
DEVELOPING LOW PRESSURE WILL MOVE N INTO THE SW GULF EARLY
SAT...AND SEND A STRONG BUT WEAKENING OCCLUDED FRONT INTO THE ERN
GULF BY LATE SAT MORNING...THEN THE FRONT SHOULD SLOWLY PUSH THRU
SE AK SAT NIGHT. AN ARCTIC FRONT WILL MOVE EWD ACROSS THE GULF
LATE SAT NIGHT INTO SUN...AND THRU SE AK LATE SUN AFTERNOON AND
EVENING. HIGH PRESSURE SHOULD BUILD OVER THE ERN PAC AND NW CANADA
MON THEN DRIFT E OF THE AREA TUE. LOOKS LIKE ANOTHER FAIRLY STRONG
OCCLUDED FRONT WILL MOVE INTO THE GULF FOR LATE TUE INTO WED.
ENDED UP USING THE 12Z ECMWF FOR 00Z SAT TO 00Z MON...THEN WENT
WITH LATEST HPC FROM 12Z MON ON OUT.

SHOULD HAVE SOME PRECIP STILL GOING ON OVER THE AREA FRI
EVENING...THEN IT SHOULD DIMINISH OVERNIGHT. ANY BREAK WILL BE
FAIRLY SHORT THOUGH AS PRECIP WITH THE NEXT SYSTEM SHOULD BE
MOVING ONSHORE EARLY SAT MORNING...AND REACH REMAINDER OF THE
PANHANDLE BY EARLY SAT AFTERNOON AT THE LATEST. SHOULD BE MOSTLY A
RAIN EVENT BUT SOME SNOW WILL LIKELY MIX IN OVER THE NRN AND ERN
AREAS AT THE ONSET. BEST CHANCE FOR ANY ACCUMULATING SNOW WITH
THIS SYSTEM WILL BE THE FAR NRN AREA NEAR THE CANADIAN
BORDER...AND HYDER. WILL PROBABLY NEED WIND HEADLINES WITH THIS
SYSTEM ESPECIALLY ALONG THE COAST SAT...MAINLY OF THE STRONG WIND
VARIETY.

AIRMASS BEHIND THE FRONT WILL BE FAIRLY MILD SO EXPECT TEMPS TO
REMAIN WELL ABOVE FREEZING SAT NIGHT AND PRECIP TO BE MOSTLY IF
NOT ALL RAIN. HOWEVER...ARCTIC FRONT WILL SWEEP E ACROSS THE AREA
LATE SUN INTO SUN EVENING...AND BRING SOMEWHAT COLDER AIR BEHIND
IT. BY LATE SUN NIGHT MOST PLACES SHOULD BE AT OR BELOW FREEZING
AND MOST PRECIP SHOULD HAVE CHANGED TO SNOW SHOWERS BY THEN.
PRECIP SHOULD DIMINISH LATER MON INTO MON NIGHT AS HIGH PRESSURE
BUILDS INTO THE AREA...AND THIS WILL ALLOW TEMPS MON NIGHT TO BE
ON THE COLD SIDE...UPPER TEENS TO UPPER 20S OVER MOST OF THE
AREA.

THEN SHOULD SEE MORE PRECIP MOVE IN LATE TUE INTO WED AHEAD OF
ANOTHER OCCLUDED FRONT. WITH COLDER AIR IN PLACE AHEAD OF IT
SHOULD SEE MORE SNOW WITH THIS SYSTEM...ALBEIT LIKELY BECOMING
MIXED WITH OR CHANGING TO RAIN ALONG THE COASTAL AND SRN
AREAS...AND POSSIBLY BECOMING MIXED PRECIP IN THE CENTRAL AREA.

MODELS SUGGEST BEGINNING OF PATTERN CHANGE LATE NEXT WEEK INTO
THE FOLLOWING WEEKEND WITH INDICATIONS OF FAIRLY STRONG RIDGE
BUILDING OVER THE ERN BERING SEA AND WRN AK AND TROF DIGGING SEWD
ALONG THE WRN COAST OF NOAM...SETTING UP POTENTIAL FOR MUCH COLDER
AIR TO MOVE INTO THE AREA. THIS PATTERN IS MORE TYPICAL OF LA NINA
WINTERS THAN WHAT HAS BEEN HAPPENING THE PAST SEVERAL WEEKS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL 9 AM AKST FRIDAY FOR AKZ017.
MARINE...GALE WARNING FOR PKZ041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>036-053.

&&

JBT/RWT