Gale Warning 470, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
343 PM AKST FRI DEC 23 2011

.SHORT TERM...AN OCCLUDED FRONT EXTENDING FROM A LOW IN THE FAR
WESTERN GULF IS BRINGING A MIX OF RAIN SNOW TO THE REGION THIS
EVENING. A NEW LOW CENTER IS EXPECTED TO DEVELOP ALONG THE ASSOC
TROUGH THIS EVENING AND MOVE NORTH NEAR YAKUTAT OVERNIGHT. SOME
GUSTY WINDS ARE OCCURRING ALONG THE FRONT THEN DIMINISH BEHIND
IT...AS NOTED ALONG THE SOUTHERN COAST WHERE THE FRONT HAS
PASSED. RAIN WILL BECOME SCATTERED BEHIND THE FRONT AND A FEW
BREAKS IN CLOUD COVER MAY LEAD TO PATCHY FOG IN THE CRAIG/KLAWOCK
AND KETCHIKAN AREAS. AFTER THE FRONT PASSES LATE TONIGHT THE
RIDGE OF HIGH PRESSURE WILL REBUILD ALONG THE PANHANDLE CAUSING
THE N-S PRESSURE GRADIENT TO INCREASE ONCE AGAIN. AS A RESULT
HAVE INCLUDED GALES THROUGH NORTHERN LYNN CANAL AND A STRONG WIND
HEADLINE FOR SKAGWAY.

 SATURDAY SEES SCATTERED RAIN POST FRONT...BECOMING MORE
PERSISTENT INTO THE AFTERNOON AND EVENING AS ANOTHER LOW MOVE
INTO THE GULF.

 MAIN FORECAST CHALLENGE HAS BEEN RAIN VS SNOW. 850 MB
TEMPERATURES WILL BE RISING THROUGH THE NIGHT WHILE SURFACE
TEMPERATURES WILL REMAIN STEADY OR FALL SLIGHTLY. THEREFORE HAVE
INCLUDED A MIX OF SNOW IN THE EVENING...TURNING TO MAINLY RAIN BY
SATURDAY.

 MODELS IN GOOD AGREEMENT IN THE NEAR TERM. USED MAINLY A BLEND
OF THE ECMWF AND NAM12 FOR THIS PACKAGE.

 &&

 .LONG TERM...FOR SAT EVENING FRONT ASSOCIATED WITH 985 MB LOW IN
THE CENTRAL GULF WILL MOVE ACROSS THE AK PANHANDLE. PRECIPITATION
WILL BEGIN AS RAIN THEN TRANSITION TO SNOW OR A RAIN SNOW MIX
THROUGH THE NIGHT AS TEMPERATURES DROP BELOW FREEZING. WITH
RESIDUAL WARM AIR IN PLACE FROM THE PREVIOUS DAY AT THIS TIME NOT
EXPECTING MUCH IN THE WAY OF SNOW ACCUMULATION. HOWEVER 850 MB
TEMPS DO DROP TO -10C THAT NIGHT SO WILL SEE SOME FAIR CAA.
NORTHERN REGIONS SHOULD HAVE A WHITE CHRISTMAS MORNING, WITH
CENTRAL AREAS SEEING SNOW OVERNIGHT WITH A MIX THROUGH THE DAY,
WHILE AREAS TO THE SOUTH MAY SEE A FEW FLAKES MIXED IN WITH THE
RAIN. THE LOW IN THE CENTRAL GULF WILL TRACK NORTH MOVING JUST
NORTHWEST OF YAKUTAT SECOND SHORTWAVE WILL INTO THE SOUTHERN AK
GULF. FOR SUN EVENING HIGH PRESSURE RIDGE WILL BUILD OVER THE
PANHANDLE WAS A STRONGER LOW IN THE NORTH PACIFIC MOVES INTO THE
SOUTHERN AK GULF DEEPENING TO AROUND 970 MB. EXPECTING WINDY
CONDITIONS TO DEVELOP ON MONDAY WITH GALE FORCE WINDS IN THE
SOUTHERN INNER CHANNELS AND COASTAL WATERS. TEMPERATURES WILL BE
AT OR JUST ABOVE FREEZING AS 850 MB TEMPS NEAR -4C AS WAA FROM
THE FRONT MOVES UP FROM THE SOUTH. NEXT LOW WILL MOVE IN MID WEEK
BUT SOME TIMING AND LOCATION DIFFERENCES AMONG THE MODELS.

 MODELS WERE IN FAIR AGREEMENT FOR THE START OF THE LONG TERM.
NAM BEGAN TO LOOK MORE OF AN OUTLIER WITH GFS AND EC IN BETTER
AGREEMENT. EC HAS BEEN GENERALLY ON THE WEAKER SIDE WITH THE LOW
CENTERS BUT NEW EC AND GFS RUNS HAVE COME MORE IN LINE WITH TIME
AND STRENGTH OF THE MONDAY LOW. THIS CAN BE SEEN ESPECIALLY WHEN
COMPARING THE 12Z EC AND 18Z GFS. FOR THE WED SYSTEM GFS BRINGS
THE LOW MUCH FURTHER NORTH INTO THE CENTRAL GULF WHILE THE EC
KEEPS THE SYSTEM TO THE SOUTH. WHILE THE EC INITIALIZED CURRENT
FEATURES A BIT TO THE EAST AND LIKED THE GFS INITIALIZATION
OVERALL LIKED THE EC SOLUTION A BIT BETTER. UPDATED GRIDS THE 00Z
EC THEN TRANSITIONED TO NEW HPC. FORECAST CONFIDENCE IS A BIT
ABOVE AVERAGE THROUGH THE WEEKEND THEN DROPS BELOW AVERAGE BY MID
WEEK DUE TO MODELS DIVERGENCE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH LATE TONIGHT FOR
     AKZ018.
MARINE...GALE WARNING FOR PKZ012-036.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>035-041>043-
     051>053.

&&

HANNON/PRB