Small Craft Advisory 800, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
6 AM AKST SUN DEC 23 2012

.SHORT TERM...
THE UPPER HIGH PRESSURE SYSTEM HAS MOVED NORTHEAST SINCE YESTERDAY
AS AN UPPER LOW WITH COLD AIR HAS DEVELOPED OVER PAKN. THIS SETUP
IS CAUSING A LIGHT S FLOW ALOFT OVER OUR FORECAST AREA FOR SOME
CLOUDS. SATELLITE AND RADAR SHOW SHOWERS OFFSHORE THOUGH EARLY THIS
MORNING ALTHOUGH ONE BAND APPEARS THAT IT COULD NICK HYDER WITH
LITTLE OR NO ACCUMULATION.

SHORT TERM OPERATIONAL MODELS FROM 23/00Z AND 23/06Z WERE IN VERY
GOOD AGREEMENT THROUGH MON 12Z. A WARM FRONT WITH WARM ADVECTION
MOVES THOUGH THE OFFSHORE WATERS THIS EVENING BUT SHOULD NOT AFFECT
LAND AREAS WITH THE THE EXCEPTION OF A THREAT OF SNOW SHOWERS FOR
YAKUTAT EARLY MONDAY MORNING. FORECASTED GALE FORCE WITH THIS
FRONT FOR THE NORTHERN OUTSIDE WATERS DUE TO THE ARCTIC HIGH WELL
INLAND TO THE NE FOR CONTINUED STRONG PRESSURE GRADIENTS TO DRIVE
THE WIND. OUTFLOW WIND AND COLD TEMPERATURES REMAIN A PROBLEM
THROUGH MONDAY MORNING DUE TO THE PERSISTENCE OF THE ARCTIC HIGH.
CONFIDENCE MODERATE TO HIGH DUE TO MODEL AGREEMENT AND SATELLLITE
PLUS OBSERVATIONAL CONFIRMATION.

.LONG TERM...SATELLITE IMAGE SHOWS SOME ENERGY AFOOT ROUGHLY 1000
MILES SOUTH OF THE ALASKA PENINSULA. THIS WILL BE OUR WEATHER
MAKER FOR CHRISTMAS EVE AND CHRISTMAS DAY. MONDAY BEGINS WITH THE
LOW IN THE WESTERN GULF WEAKENING AS THE AFOREMENTIONED SYSTEM
BEGINS ITS TREK NORTHWARD. WHILE THE WESTERN GULF LOW WEAKENS AND
SLOWLY MOVES WESTWARD...RIDGING ALOFT WILL HELP THE SURFACE RIDGE
IN CANADA BRIEFLY STRENGTHEN THUS INCREASING THE PANHANDLE PRESSURE
GRADIENTS OVER THE PANHANDLE LATE MONDAY. MONDAY NIGHT MANY OUTSIDE
WATER SOUTHEAST WINDS WILL BECOME MORE EASTERLY AND REACH GALE
FORCE IN THE SOUTHERN OUTSIDE WATERS. ALSO...LOOK FOR INCREASING
WINDS AGAIN IN LYNN...STEPHENS...AND CHATHAM MONDAY NIGHT INTO
TUESDAY AS WELL. BY CHRISTMAS DAY...MODEL SOLUTIONS BEGIN TO
DIVERGE A BIT WITH THE GFS TAKING A MORE WESTERLY POSITION AND THE
EC A BIT CLOSER TO HAIDA GWAII. BOTH MODELS HAVE STRENGTHENED THE
LOW. HAVE NUDGED A LITTLE MORE GFS AS IT KEEPS OUR PREVIOUS
FORECAST TRACK IN TACT WHILE STILL INCREASING WINDS WITH THE
STRENGTHENED LOW. IN ADDITION...GFS HAS REMAINED MORE CONSISTENT
WITH PREVIOUS RUNS THAN THE EC. HOWEVER BY TUESDAY AFTERNOON
...INCORPORATED A LITTLE MORE EC AS GFS SEEMS TO DISSIPATE THE LOW
TOO QUICKLY. BY WEDNESDAY...DIFFERENCES BECOME LESS SIGNIFICANT.

THE STRONGER LOW...CLOSER TO THE COAST...HAS NUDGED POPS IN THE
SOUTH AND BARONOF ISLAND A LITTLE HIGHER. HOWEVER...MUCH OF THE
PANHANDLE...PARTICULARLY IN THE NORTH CENTRAL AND INTERIOR WILL
REMAIN DRY THROUGH CHRISTMAS DAY.

THE OTHER STORY IS THE SCHEDULED WARM UP...TO BEGIN MONDAY AND EVEN
MORE SO MONDAY NIGHT. MADE FEW CHANGES TO TEMPERATURES AS THEY
SEEMED SET...WITH THE EXCEPTION OF VERY SLIGHT COOLING IN THE
SOUTHERN AND CENTRAL INTERIOR WITH THE CLEARING SKIES ASSOCIATED
WITH THE PRE-SYSTEM RIDGING. COASTAL LOCATIONS THOUGH WILL SEE
STEADY BUT SLOW WARMING THROUGH MONDAY NIGHT...SUGGESTING SNOW
CHANCES POSSIBLY TURNING TO RAIN CHANCES LATE. BY WEDNESDAY...THE
FREEZING LINE WILL ROUGHLY LIE ALONG A LINE FROM YAKUTAT NORTHERN
PRINCE OF WALES ISLAND...AND TO KUPREANOF ISLAND BY THURSDAY.

SOUTHERLY FLOW WILL REMAIN THE RULE WEDNESDAY THROUGH SATURDAY AS
THE LOW IN THE WESTERN GULF REMAINS STATIONARY. THUS EXPECT
PRECIPITATION CHANCES AND WARM TEMPERATURES TO CONTINUE THROUGH
SATURDAY.
&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH TONIGHT FOR AKZ025.
         STRONG WIND THROUGH THIS AFTERNOON FOR AKZ017-019-029.
         WINTER WEATHER ADVISORY UNTIL 4 PM AKZ018.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011-013.
         GALE WARNING FOR PKZ011>013-022-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-031>036-041-042-053.

&&

JC/JWA