Gale Warning 346, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST FRI NOV 30 2007

.SYNOPSIS...EXTREMELY HIGH AMPLITUDE UPR RIDGE OVER THE CENTRAL
GULF OF ALASKA WITH A DEEP LOW OVER THE CENTRAL BERING SEA AND
THE DOWNSTREAM MAJOR OVER HUDSON BAY. AT 250 MB...A NORTH JET HAS
DEVELOPED UP TO 130 KT ALONG 138W AT 12Z. LOTS OF AIR SINKING
WITH RAPID COOLING IN CLEAR AIR FOR WINTERTIME SFC TEMPERATURES.
CANADIAN SFC ANALYSIS AT 12Z HAS THE HIGH 1048 MB NEAR DAWSON.

.SHORT RANGE...ALL MODELS IN AGREEMENT THAT OFFSHORE SURFACE
PRESSURE GRADIENTS WILL STEADILY INCREASE OVER THE NEXT COUPLE OF
DAYS. FORECAST CHALLENGES ARE MAGNITUDE OF THE WIND SPEED FOR
BOTH MARINE AND PUBLIC AND SOME LLWS FOR AVIATION. WILL START
FORECASTING WIND ADVISORIES FOR SOME NORTHERN ZONES WITH SKAGWAY
ALREADY IN EFFECT AT NOON. TONIGHT LOOKS WINDY AND INCREASING
SATURDAY. AT TRANSITION TO LONG TERM MUST CONSIDER WIND CHILL
ALONG THE KLONDIKE HIGHWAY AND INCREASING TAKU WIND SATURDAY EVE
BUT BELOW WARNING CRITERIA FOR NOW.

.LONG RANGE...VERY COLD AIR PUSHING WEST FROM THE CANADIAN
INTERIOR AT THE BEGINNING OF THE EXTENDED RANGE DISCUSSION.
COMBINED WITH CLEAR TO PARTLY CLOUDY SKIES...NIGHT TIME LOWS WILL
BE IN THE LOW TEENS OVER THE INNER CHANNELS AND MID TO UPPER
TEENS ALONG THE OUTER COAST THROUGH EARLY NEXT WEEK. A STRONG
NORTHERLY PRESSURE GRADIENT WILL RESULT IN ADVISORY LEVEL WINDS
THROUGH THE WEEKEND AND LAST INTO THE EARLY WEEK IN SOME
LOCATIONS. THE COLD TEMPERATURES AND STRONG NORTHERLY WINDS MAKE
WIND CHILL AND FREEZING SPRAY MORE OF A CONCERN. CURRENT THINKING
IS THAT WIND CHILL WILL MAY REACH ADVISORY LEVELS ALONG THE
KLONDIKE AND HAINES HIGHWAYS LATER THIS WEEKEND AS INDICATED
ABOVE. REGARDING FREEZING SPRAY...CURRENT SEA SURFACE
TEMPERATURES IN LYNN CANAL ARE GETTING COLD ENOUGH FOR FREEZING
SPRAY TO OCCUR AT NIGHT WHEN TEMPS ARE COLDEST.

ARRIVAL OF PRECIP FROM THE SOUTH IS SLOWER IN THE CURRENT MODEL
RUN AND WILL BE MAKING SOME CHANGES TO POP GRIDS TODAY TO REFLECT
THIS. AM EXPECTING SNOW TO BEGIN SUNDAY NIGHT IN THE SOUTHERN
PANHANDLE AND SPREAD NORTH TO ARRIVE IN THE SKAGWAY AREA LATE
MONDAY. HEAVIEST SNOWFALL WILL BE OVER THE COASTAL MOUNTAINS AND
HEAVY SNOW WARNINGS REMAIN A POSSIBILITY FOR THESE LOCATIONS.
MUCH LESS SNOWFALL ALONG THE OUTER COAST BUT THINK ALL PANHANDLE
LOCATIONS WILL SEE AT LEAST SOME SNOW.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORY 18 AND 19.

MARINE...SMCR ALL WATERS.

JCC/FCF