Small Craft Advisory 808, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
400 PM AKST WED DEC 26 2012

.SHORT TERM...MOSTLY CLEAR SKIES THIS EVENING WILL AGAIN CAUSE
TEMPERATURES TO FALL QUICKLY TO THEIR MINIMUMS. HOWEVER...CLOUDS
WILL INCREASE OVERNIGHT AS A FRONT MOVES INTO THE EASTERN GULF.
THIS FRONT WILL CAUSE WINDS TO INCREASE TO GALE FORCE OVER THE
OUTSIDE WATERS WITH GUSTS TO 35 MPH ALONG THE COASTAL LAND AREAS.
PRECIP WILL START OFF AS SNOW EARLY THURSDAY MORNING THEN MOVE
INTO THE THE INNER CHANNELS AND INCREASE IN INTENSITY THROUGH THE
AFTERNOON. TEMPERATURES WILL RISE AS THE FRONT APPROACHES AND
CAUSE THE PRECIP TO FALL AS MAINLY RAIN IN SITKA AND THE KLAWOCK
AREAS. THE WARMING ALOFT WILL CAUSE THE SNOW TO BECOME HEAVY AND
WET. THE CENTRAL INNER CHANNELS WILL SEE THE GREATEST SNOWFALL
RATES IN THE AFTERNOON AND EARLY EVENING. HAVE ISSUED A WINTER
WEATHER ADVISORY FOR GUSTAVUS...HOONAH...ANGOON...JUNEAU...AND
PETERSBURG AND WRANGELL. A RANGE OF 3-9 INCHES OF SNOW IS
EXPECTED THROUGH THURSDAY NIGHT BEFORE STARTING TO MIX WITH THEN
CHANGE TO RAIN. SEE THE ADVISORY STATEMENT FOR MORE DETAILS ON
AMOUNTS AND TIMING FOR EACH LOCATION.

 USED MAINLY THE NAM12 AND LOCAL WRF MODELS FOR UPDATES TODAY.
FORECAST CONFIDENCE IS AVERAGE.

 &&

 .LONG TERM...THE EXTENDED RANGE BEGINS ON THURS NIGHT WITH THE
FIRST FRONT STILL MAKING ITS WAY THROUGH THE PANHANDLE. BY THIS
POINT SOME AMOUNT OF SNOW WILL HAVE FALLEN IN MOST AREAS AND THE
CENTRAL AND SOUTHERN PANHANDLE WILL BE THREATENING OR HAVE
ALREADY CHANGED OVER TO RAIN. THE INTENSITY OF THE PRECIP WILL BE
BEGINNING TO DIMINISH IN THE NORTHERN PANHANDLE AND ALONG THE
OUTER COAST. FOR THE SOUTHERN INNER CHANNELS THE PRECIP INTENSITY
WILL CONTINUE THROUGH THE NIGHT. AREAS WHERE THE PRECIP REMAINS
SNOW INTO THE NIGHT WILL SEE A GOOD FEW INCHES OUT OF THIS SYSTEM
ESPECIALLY THE FARTHER SOUTH YOU ARE AS THE HIGHEST MOISTURE IS
IN THE SOUTHERN PANHANDLE. AS SUCH HAVE EXTENDED THE WINTER
WEATHER ADVISORIES THAT WERE IN THE SHORT TERM INTO THE THURS
NIGHT PERIOD.

 BEHIND THE FRONT IS A PAIR OF SHORT WAVES TROUGHS THAT WILL BE
ROTATING INTO THE PANHANDLE. THIS FIRST IS RIGHT ON THE HEELS OF
THE FRONT AND WILL BRING SOME ENHANCED PRECIP TO THE NORTHERN
PANHANDLE EARLY FRI. A SECOND WEAKER TROUGH SHOWS UP FOR FRI
EVENING. IT WILL NOT ENHANCE THE PRECIP MUCH BUT WILL MAKE IT
LAST FOR A WHILE LONGER. PRECIP TYPE WILL BE RAIN OR A MIX FROM
ICE STRAIT AND YAKUTAT SOUTHWARD BY THE TIME THE SECOND TROUGH
MAKES IT IN DUE TO CONTINUED WARM AIR ADVECTION ESPECIALLY DURING
THE DAY.

 FOR THE REST OF THE LONG RANGE, AT LEAST 3 MORE FRONTS WILL MAKE
THEIR WAY TOWARD THE PANHANDLE THROUGH MID NEXT WEEK. THE FIRST
IS FAIRLY WEAK AND MAY NOT GET PAST YAKUTAT BEFORE THE NEXT FRONT
SWALLOWS IT ON SUN. FRONT NUMBER TWO COMES FOR SUN AFTERNOON INTO
SUN NIGHT AND IS MUCH MORE ORGANIZED. IT COULD BRING SOME STRONG
WINDS TO THE OUTER COAST AND SOUTHERN PANHANDLE. FRONT NUMBER
THREE IS A BIT HARDER TO PIN DOWN TIMING AND HOW STRONG IT WILL
BE BUT THE MODELS SEEM TO FAVOR EARLY TUES FOR THIS ONE TO COME
IN.

 MODEL AGREEMENT THROUGH THE EXTENDED LOOKS FAIRLY GOOD UP UNTIL
THE WEEKEND. SOME DIFFERENCES START TO APPEAR WITH THE SECOND
FRONT THAT WILL BE COMING IN FOR SUN. ECMWF IS A BIT FASTER WITH
IT THEN THE GFS IS. THINGS REALLY START FALLING APART BY EARLY
NEXT WEEK AS THE MODELS TRY TO FIGURE OUT THE VARIOUS WEAK WAVES
THAT WILL FOLLOW IN THE WAKE OF THE SECOND FRONT. DECIDED ON A
BLEND OF THE ECMWF AND GFS AS BOTH SEEMED TO STILL BE DOING A
GOOD JOB CONSISTENCY WISE THROUGH SAT. THEN ADDED MORE HPC INTO
THE MIX TO TRY AND EVEN OUT THE DIFFERENCES FARTHER OUT. FORECAST
CONFIDENCE IS GOOD OVERALL BUT FORECAST SNOWFALL CONFIDENCE IS
BELOW AVERAGE SINCE THAT DEPENDS ON HOW FAST THE WARM AIR
ADVECTION PUSHES THE RAIN/SNOW LINE NORTHWARD ON THURS NIGHT AND
FRI.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY FROM 9 AM THURSDAY TO 3 AM AKST FRIDAY
     FOR AKZ020-026.
         WINTER WEATHER ADVISORY FROM 9 AM TO 9 PM AKST THURSDAY FOR
     AKZ021-024.
         WINTER WEATHER ADVISORY FROM NOON THURSDAY TO 3 AM AKST FRIDAY
     FOR AKZ025.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         GALE WARNING FOR PKZ022-036-042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-012-021-031-033>035-041.

&&

HANNON/EAL