Small Craft Advisory 818, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
426 PM AKST SAT DEC 29 2012

.SHORT TERM...RATHER ACTIVE SHORT TERM FORECAST IN THE WORKS AS
A 955 MB STORM FORCE LOW MOVES TOWARD KODIAK ISLAND INTO SUNDAY.
THE ASSOCIATED FRONT WILL APPROACH THE PANHANDLE TONIGHT BRINGING
SMALL CRAFT AND GALE FORCE WINDS FOR MOST OF THE GULF WATERS AND
SOUTHERN INNER CHANNELS. THE EXTREME NORTHERN GULF MAY SEE A
BRIEF PERIOD OF STORM FORCE WINDS LATE TONIGHT AS THE USUAL
BARRIER JET SETS UP ALONG THE NORTHERN GULF COAST.

 FOR THE INNER CHANNELS PRECIP AND WIND WILL BE INCREASING
THROUGH THE NIGHT AND INTO TOMORROW. WINDS ACROSS THE AREA HAVE
FINALLY SWITCHED AROUND TO THE S IN MOST PLACES AS WEAK WARM AIR
ADVECTION HAS CONTINUED ACROSS THE PANHANDLE FOR THE LAST FEW
DAYS. STILL THERE ARE PLACES THAT REMAIN AT OR BELOW FREEZING
TODAY. WRANGELL IS SITTING RIGHT AT 32 DEGREES WHERE A LIGHT NW
WIND HAS BEEN BLOWING FOR THE PAST FEW DAYS. HYDER IS SITTING IN
THE MID 20S. AND THE LAST PLACE IS HAINES AND THE HAINES HIGHWAY
SITTING IN THE LOW TO MID 20S WHERE A STEADY NW WIND HAS BEEN
BLOWING DESPITE THE NOW STRONG S WIND IN LYNN CANAL. WITH THE
INCREASING PRECIP THE ABOVE MENTIONED PLACES HAVE THE BEST
POSSIBILITY OF SEEING SNOW LATE TONIGHT AND INTO TOMORROW. HAINES
AND THE HAINES HIGHWAY IN PARTICULAR HAVE THE BEST CHANCE OF
SEEING SOME SIGNIFICANT SNOW OUT OF THIS FRONT. SO HAVE DECIDED
TO LIFT A WINTER WEATHER ADVISORY FOR THE HAINES AREA
PARTICULARLY THE HIGHWAY FOR LATE TONIGHT AND THROUGH TOMORROW.
IN OTHER PLACES TEMPERATURES WILL BE TOO WARM FOR SNOW, OR MAY
SEE A RAIN/SNOW MIX AT MOST AS WARM AIR ADVECTION CONTINUES.

 FARTHER SOUTH THE CONCERN TURNS FROM PRECIP TO WIND. SOUTHERN
BARANOF ISLAND AND HYDABURG ARE THE PLACES THAT ARE THE MOST
LIKELY TO SEE STRONG WINDS AS FIRST THE FRONT APPROACHES THE
COAST THEN THE WEAK WAVE STARTS ADVANCING NORTHWARD. HAVE DECIDED
TO HOIST A STRONG WIND HEADLINE FOR ZONES 23 FOR TOMORROW, AND
ZONE 27 FOR TOMORROW AFTERNOON. I AM ONLY EXPECTING GUSTS UP TO
40 TO 45 MPH IN THESE AREAS.

 MODEL AGREEMENT TODAY WAS ALL RIGHT BUT THERE WERE SOME
DIFFERENCES IN INITIALIZATION OF THE MAIN LOW. ECMWF AND NAM
SEEMED TO BE TOO FAR WEST COMPARED TO SATELLITE OBSERVATIONS. GFS
AND UK HAD A MUCH BETTER FIT. ALSO WITH THE WEAK WAVE ON SUN
AFTERNOON THE GFS HAD THE BEST CONSISTENCY ON TRACK AND TIMING.
MAINLY DECIDED TO USE THE GFS FOR UPDATES IN THE SHORT RANGE
TODAY. FORECAST CONFIDENCE IS ABOUT AVERAGE.

.LONG TERM...THE LONG TERM BEGINS WITH A SHORTWAVE FORMING NEAR
THE TRIPLE POINT ALONG THE FRONT OF THE PARENT LOW BARRELING
THROUGH SOUTHWEST ALASKA. THIS SHORTWAVE IS SLIGHTLY STRONGER THAN
PREVIOUSLY FORECAST AND THEREFORE HAVE RAISED WIND SPEEDS ACROSS THE
OUTSIDE WATERS...TO STRONGER GALE IN SOME AREAS AND TO GALE FORCE
IN OTHERS. THE SHORTWAVE WILL RUSH NORTHWARD ALONG WITH THE FRONT.
STRONG WINDS WILL BLOW ALONG THE COAST SOUTH OF CAPE SPENCER. IN
ADDITION...HAVE BOOSTED WIND SPEEDS THROUGH CLARENCE STRAIT WITH
FRONTAL PASSAGE THIS EVENING AND WILL DECLINE FAIRLY RAPIDLY
OVERNIGHT INTO MONDAY MORNING. PRE-FRONTAL PRECIPITATION AND COLD
AIR ALONG THE HAINES HIGHWAY WILL COMBINE TO MAKE FOR SOME HEALTHY
AMOUNTS OF WET SNOW THUS EXTENDING A WINTER WEATHER ADVISORY
THROUGH SUNDAY EVENING.

TEMPERATURES WILL COOL A LITTLE BEHIND THE FRONT BUT AS MUCH OF
THE AIR IS A MARINE MODIFIED COOL AIR MASS, NOT EXPECTING ANY BIG
CHANGES FOR MONDAY. SHOWERS WILL DIMINISH THROUGH THE DAY AND
EVENING MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE PANHANDLE
MONDAY NIGHT. TUESDAY ANOTHER SURFACE LOW WILL ENTER THE WESTERN
GULF AND TRACK NORTHWARD. ITS SURFACE FRONT WILL PLOW NORTHWARD AND
RAISE POPS AND WINDS AGAIN...ESPECIALLY ALONG THE WESTERN OUTSIDE
WATERS AND THE NORTHWEST PANHANDLE FOR TUESDAY NIGHT. ALSO TUESDAY
NIGHT...ANOTHER WEAKER LOW WILL DEVELOP TO THE SOUTHEAST OF THE
PREVIOUS LOW AND ENTER OUR WATERS TUESDAY NIGHT AND TRACK NORTH-
NORTHWEST TOWARD ICY BAY THROUGH WEDNESDAY MORNING. THIS HAS BEEN
A CHANGE FROM PREVIOUS FORECAST OF ANOTHER OPEN WAVE. THUS HAVE
RAISED WINDS AGAIN OVER THE SOUTHEAST WATERS TO REFLECT THIS
CHANGE.

BEYOND WEDNESDAY...ACTIVE WEATHER PATTERN CONTINUES...WITH UPPER
LEVEL LOW OVER BRISTOL BAY WEAKENING THROUGH FRIDAY AND SOUTHERLY
FLOW ALOFT OVER SOUTHEAST ALASKA EVOLVING TO A MORE SOUTHWESTERLY
FLOW WITH INDIVIDUAL SHORTWAVES BRINGING IN LIKELY PRECIPITATION
THROUGH THE FIRST PART OF THE WEEKEND. OVERALL...WE ARE LOOKING AT
AN EXTENDED PATTERN OF MILDER TEMPERATURES AND WETTER WEATHER...A LITTLE
DIFFERENT THAN THE UNSEASONABLE WINTER SOUTHEAST HAS EXPERIENCED
THUS FAR.

MODEL OF CHOICE WAS GFS SUNDAY NIGHT INTO WEDNESDAY MORNING. AS
HPC GUIDANCE SHIFTED A BIT TODAY FOR TUESDAY NIGHT AND WEDNESDAY
TO A MORE GFS FRIENDLY SOLUTION. GFS ALSO SEEMED TO INITIALIZE
BETTER OVER THE NEAR NORTH PACIFIC AT THE SURFACE. MODEL AGREEMENT
WAS NOT TOO GREAT SUNDAY NIGHT INTO MONDAY. MONDAY NIGHT...EC AND
GFS CAME TOGETHER BUT THEN DIVERGED YET AGAIN FOR THE LATE TUESDAY
LOW MOVING INTO THE GULF. FROM WEDNESDAY NIGHT AND BEYOND...HPC
GUIDANCE CHANGED LITTLE FROM YESTERDAY...THUS MADE FEW CHANGES
DURING THIS TIME PERIOD. FORECAST CONFIDENCE AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND SUNDAY AFTERNOON FOR AKZ027.
         STRONG WIND FROM 3 AM AKST SUNDAY THROUGH SUNDAY AFTERNOON FOR
     AKZ023.
         WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT AKST
     SUNDAY NIGHT FOR AKZ019.
MARINE...STORM WARNING FOR PKZ052.
         GALE WARNING FOR PKZ033-036-041>043-051.
         SMALL CRAFT ADVISORY FOR PKZ011>013-022-032-034-035-053.

&&

EAL/JWA