Small Craft Advisory 803, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
310 PM AKST MON DEC 24 2012

.SHORT TERM...SCATTERED SNOW SHOWERS THAT THAT WERE AROUND EARLY
THIS MORNING HAVE MOVED WEST OF YAKUTAT THIS AFTERNOON. A LOW
PRESSURE SYSTEM SLOWLY MOVING NORTH OUT OF THE PACIFIC HAS CAUSED
INCREASED OFFSHORE FLOW OVER THE PANHANDLE TODAY. THIS HELPED TO
DIMINISH THE CLOUD COVER AS WELL. WITH MOSTLY CLEAR SKIES AT
SUNSET TONIGHT...EXPECT THE TEMPERATURE TO DROP A FEW DEGREES
QUICKLY IN WIND SHELTERED AREAS THEN REMAIN STEADY OR SLOWLY
RISING THROUGH THE NIGHT AND TUESDAY. CLOUD COVER ASSOC WITH THE
NORTH PACIFIC LOW HAS STARTED TO MOVE INTO THE FAR SOUTHERN
COAST...MAINLY THIN HIGH CLOUDS. PRECIP WITH THE ASSOC FRONTAL
BAND WILL MOVE INTO THE KLAWOCK AREA LATER TONIGHT BUT SHOULD BE
LIGHT AND SCATTERED WITH LESS THAN HALF AN INCH OF ACCUMULATION
THROUGH TUESDAY MORNING. THIS IS IN PART DUE TO THE WARMING
TEMPERATURES AND SOME MIXING WITH RAIN OVERNIGHT. THE PORT
ALEXANDER AND LITTLE PORT WALTER AREAS WILL SEE SLIGHTLY MORE
SNOW DUE TO UPSLOPING AND TEMPERATURES REMAINING AR OR BELOW
FREEZING...UP TO AN INCH OF ACCUMULATION IS POSSIBLE THERE.

 WINDS WILL INCREASE WITH THE FRONTAL BAND. HAVE THE SOUTHERN
OUTSIDE WATERS REACHING 40KT TONIGHT AND THE SITKA AND KLAWOCK
ZONES TO SEE GUSTS OF 40MPH LATER. THE LOW MOVING NORTH WILL ALSO
CAUSE MANY OF THE MARINE ZONES TO SEE INCREASED NORTHERLY
GUSTS...ESPECIALLY OUT OF NE INTERIOR PASSES. HAVE STORM FORCE
WINDS FOR NORTHERN LYNN...BUT THAT IS ISOLATED TO THE TAIYA INLET
AREA AS THAT CHANNEL IS ORIENTED MORE NELY. DOWNTOWN JUNEAU HAS
STARTED TO GET MORE GUSTS THIS AFTERNOON AND WITH EXPECTED
PRESSURE GRADIENT INCREASE HAVE INCLUDED A STRONG WIND HEADLINE
FOR THERE WITH GUSTS TO 40MPH. WINDS AND PRECIP WILL EASE THROUGH
TUESDAY AFTERNOON AS THE LOW WEAKENS AND STARTS TO MOVE SOUTH
ONCE AGAIN.

 USED MAINLY THE NAM12 AND LOCAL HIGH RESOLUTION WRF MODEL FOR
UPDATES TODAY. FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...MODELS ARE IN GENERAL AGREEMENT THROUGH THURSDAY
WITH AN INCOMING LOW ACROSS THE GULF AND ASSOCIATED FRONTAL
PASSAGE APPROACHING THE PANHANDLE. WITH MINOR TIMING
DIFFERENCES...THE NAM AND ECMWF MADE A GOOD CONSENSUS AND WERE
USED TO REFRESH THE INHERITED FORECAST PACKAGE THROUGH EARLY
THURSDAY EVENING. A WARMING TREND IS IN STORE WITH THE INCOMING
FRONTAL BOUNDARY...BUT EXISTING COLD AIR WILL PRODUCE SNOW
INITIALLY AT THE TIME OF ONSET FRONTAL PASSAGE. SOUTHEAST TO SOUTH
LOW LEVEL WINDS WILL CONTINUE TO INCREASE AND CAUSE THE
PRECIPITATION MIXING WITH RAIN FROM THE SOUTH. THE NORTHERN MOST
PANHANDLE WILL CONTINUE TO SEE SNOW AND SOME OVERRUNNING MAY OCCUR
WITH THE FRONTAL BOUNDARY FOR POTENTIAL SIGNIFICANT SNOW
ACCUMULATION ON THURSDAY.

 THE PROLONGED ARCTIC HIGH WILL WEAKEN BY THE MIDDLE OF WEEK AND
NORTHERLY PRESSURE GRADIENT WILL CONSEQUENTLY RELAX AND OFFSHORE
FLOW WILL GRADUALLY DIMINISH. AHEAD AND ALONG THE INCOMING
FRONT...WINDS ACROSS THE OUTER WATERS WILL INCREASE TO SOLID SMALL
CRAFT TO GALE FORCE WEDNESDAY AND THURSDAY. MODELS BEGIN
STRUGGLING LATE THURSDAY THROUGH THE WEEKEND...BUT GENERALLY KEEP
A CONTINUED WARMING TREND FOR RAIN FOR MOST AREAS WITH MIXED
PRECIPITATION OVER THE NORTHERN MOST PANHANDLE. LEANED OVER THE
HPC APPROACH FOR THE REMAINING LONG TERM PERIODS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH LATE TONIGHT FOR
     AKZ027.
         STRONG WIND THROUGH TUESDAY AFTERNOON FOR AKZ025.
         STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH TUESDAY MORNING
     FOR AKZ023.
         STRONG WIND THROUGH TUESDAY AFTERNOON FOR AKZ019.
         STRONG WIND THROUGH TUESDAY AFTERNOON FOR AKZ018.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         STORM WARNING FOR PKZ012.
         GALE WARNING FOR PKZ013-022-031-033>036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-021-032-053.

&&

HANNON/AHN