Small Craft Advisory 48, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
400 PM AKST SAT JAN 15 2011

.SHORT TERM... SATELLITE IMAGERY SHOWS THE AREA OF CLOUDS AND
SNOW HAS ADVANCED AS FAR NORTH AS JUNEAU HOWEVER THE HIGHER
CLOUDS ARE MORE BANDED THAN SOLID AND AS A RESULT THE SNOWFALL IS
QUITE VARIABLE. SURFACE OBSERVATIONS SHOW LIGHT SNOW IS FALLING
OVER MOST OF THE SOUTHERN TWO THIRDS OF THE PANHANDLE BUT
TEMPERATURES HAVE WARMED ABOVE FREEZING IN THE EXTREME SOUTH AND
A SLOW WARMING IS EXPECTED TO CONTINUE THROUGH SUNDAY. BECAUSE OF
THE STRONGER THAN EXPECTED WARM UP A WINTER STORM WARNING FOR
HEAVY SNOW IS CURRENTLY ONLY IN EFFECT FOR ZONE 29 AND A WINTER
WEATHER ADVISORY FOR SNOW IS CONTINUED FOR ZONE 26. LITTLE CHANGE
IS EXPECTED TO THE THE GENERAL WARM MOIST OVERRUNING CONDITION
THROUGH SUNDAY OTHER THAN A VERY GRADUAL MODIFICATION OF THE
ARCTIC OUTFLOW AIRMASS BELOW.

 MODELS ARE FAIRLY CONSISTENT WITH THE SYNOPTIC PATTERN. STRONG
HIGH PRESSURE WILL CONTINUE IN THE YUKON THROUGH EARLY SUNDAY
WHICH WILL MAINTAIN THE INTENSE NORTH TO NORTHEAST WINDS IN THE
NORTHERN AND INTERIOR ZONES WHILE KEEPING TEMPERATURES COLD. A
WINTER STORM WARNING FOR DANGEROUS WIND CHILLS WAS ISSUED FOR
ZONE 18 WHICH INCLUDES SKAGWAY AND THE KONDIKE HIGHWAY. THESE
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH EARLY SUNDAY.
&&

.LONG TERM...WE WILL BE IN A SLOW WARM UP THROUGH THE LONG TERM.
ONE LAST BURST OF ARCTIC AIR SUNDAY NIGHT BEFORE RIDGE BUILDS INTO
GULF AND GO TO ONSHORE FLOW. DO HAVE A SHORT WAVE IN WESTERLY FLOW
THAT MOVES ACROSS PANHANDLE MONDAY AND A WEAK SYSTEM THAT APPROACHES
FROM SW ON TUESDAY. THESE SYSTEMS WILL BRING SNOW TO THE INNER
CHANNELS WITH A MIX OF RAIN AND SNOW ALONG THE IMMEDIATE COAST.

A STRONGER FRONTAL SYSTEMS MOVES INTO THE EASTERN GULF WEDNESDAY
WITH GALES. PRECIP WILL INCREASE ACROSS PANHANDLE AND COULD SEE
ADVISORY LEVEL SNOWS FOR INNER CHANNELS WED-THU. HAVE PRECIP GOING
TO ALL RAIN EXCEPT FOR PAHN-PAGY THU NIGHT AND FRI.

MODELS IN GOOD SYNOPTIC AGREEMENT. USED NAM FOR PRES-WIND THROUGH
DAY 3.5 BUT IT IS WAY TOO COLD (HAD A -12C COLD BIAS AT PAKT THIS
MORNING) IN THE BOUNDARY LEVEL. PRIMARILY USED GFS FOR TEMPS AND
OTHER FIELDS THROUGH DAY 4 AND HPC GRIDS DAYS 4-8.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 3 AM AKST SUNDAY FOR AKZ026.
         WIND ADVISORY UNTIL NOON AKST SUNDAY FOR AKZ017-019-020-022-025.
         WINTER STORM WARNING UNTIL 3 PM AKST SUNDAY FOR AKZ018-029.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011>013-021-022-031-032-043.
         STORM WARNING FOR PKZ011>013.
         GALE WARNING FOR PKZ021-022-031-032-034-035-042.
         SMALL CRAFT ADVISORY FOR PKZ033-036-041-043-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ052.

&&

CFD/MM