Small Craft Advisory 1039, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AST MON DEC 10 2007

.MODEL DISCUSSION...FOR SUCH AN ACTIVE WEATHER PATTERN THE MODELS ARE
DOING FAIRLY WELL. THE IMMEDIATE WEATHER CONCERN IS THE LOW NEAR
KODIAK ISLAND. THIS LOW IS CURRENTLY JUST EAST NORTHEAST OF KODIAK
ISLAND AND ABOUT TO MAKE ITS TURN TOWARD THE RIGHT. THIS TURN HAS
BEEN A POINT OF CONTENTION THE LAST FEW DAYS AS THE MODELS HAD A
RADICAL SHIFT IN THE LOWS MOVEMENT A FEW DAYS AGO AND HAVE NOW CALMED
DOWN ON LITTLE ON IT. THE LOW IS INITIALIZED WELL BY THE GFS AND THE
18Z POSITION ON IT TODAY THROUGH THIS EVENING LOOKS GOOD. HOWEVER THE
GFS SEEMS TO MOVE IT TOO FAR SOUTH IN BRINGING IT SOUTH OF MIDDLETON
ISLAND TOMORROW. THE NAM ACTUALLY LOOKS TO HAVE A MORE FAVORABLE
POSITIONING ON IT TUESDAY AND WEDNESDAY. ANOTHER FEATURE UNIQUE TO
THE NAM IS IT HAS A RESIDUAL LOW IN THE NORTH GULF COAST AND WESTERN
PRINCE WILLIAM SOUND TUESDAY AND TUESDAY NIGHT. THIS IS A FEATURE
THAT WE HAVE BEEN EXPECTING TO FORM IN THIS AREA AROUND THAT TIME DUE
TO THE STRONG WINDS AND COLD AIR ADVECTION THROUGH THE KAMISHAK GAP
THAT WILL FLOW INTO THE NORTH GULF COAST. THIS FEATURE IS NOW BEING
HINTED AT BY THE NAM WITH ITS HIGH RESOLUTION.

IN THE BERING SEA AREA...THE LOW IN THE NORTHERN BERING SEA IS
HANDLED WELL BY ALL MODELS AND THE FOUR MAJOR MODELS HAVE A COMMON
AGREEMENT ON THE PATH OF THE LOW THAT IS SOUTH OF KISKA THIS
AFTERNOON. THE GOOD NEWS ON THIS LOW IS THAT THE PATH LOOKS TO BE
WHERE THE GFS WAS PUTTING IT FROM YESTERDAYS MODEL RUNS WHICH IS THE
PATH THAT WAS USED IN THE FORECASTS. IT SHOULD END UP IN SHELIKOF
STRAIT WEDNESDAY AFTERNOON AND THEN HEAD TOWARD MIDDLETON ISLAND. AT
THIS POINT THE MODELS BEGIN TO BREAK DOWN WITH EACH OTHER AND ALSO
INTERNALLY. THE GFS ENSEMBLE MEAN MSL PRESSURE AND THE OPERATIONAL
RUN BEGIN TO DIVERGE THURSDAY AND THIS JUST GETS WORSE AS WE HEAD
TOWARD THE WEEKEND.

.ANALYSIS AND UPPER LEVELS...THE LOW EAST NORTHEAST OF KODIAK ISLAND
WILL BEAR WATCHING FOR ITS EXACT COURSE AS IT MOVES INTO THE NORTH
GULF COAST THIS EVENING. THE OTHER FACTOR THAT WILL BE A BIG PART OF
THE FORECAST WILL BE THE AMOUNT OF COLD ADVECTION OUT OF THE SUSITNA
VALLEY THAT WILL COME INTO THE ANCHORAGE AREA ND KENAI PENINSULA. SO
FAR TODAY THE WARM ADVECTION THROUGH THE CHUGACH MOUNTAINS HAS BEEN
SOMEWHAT MITIGATED BY THE COLDER AIR WITH DEWPOINTS REMAINING BELOW
FREEZING FOR ALMOST ALL OF THE SUSITNA VALLEY THE CENTRAL KENAI
PENINSULA AREA. HOW FAR EAST AND HOW FAST THE LOW MOVES WILL BE THE
MAIN FACTOR IN WHETHER THE WARM AIR IS ABLE TO MOVE WEST OF THE
CHUGACH MOUNTAINS. WARMER AIR IS MOVING THOUGH TURNAGAIN ARM BUT THE
STRONG LOW TO THE SOUTH IS MAKING THE TURNAGAIN ARM JET MAKE A SHARP
LEFT HAND TURN DOWN COOK INLET WHERE IT IS MIXING WITH THE COOLER AIR
MOVING DOWN THE INLET OUT OF THE SUSITNA VALLEY.

.SHORT TERM FORECAST...PRECIPITATION SHOULD REMAIN RAIN ALONG THE
IMMEDIATE NORTH GULF COAST THROUGH THE NIGHT. VALDEZ WILL PROBABLY
MIX IN WITH RAIN AT TIMES OVERNIGHT BUT BY TOMORROW ALL PRECIPITATION
SHOULD TURN TO SNOW.
BRISTOL BAY WILL CONTINUE TO SEE RAIN OR RAIN AND SNOW IN THE EASTERN
PART OF THE ZONE TURNING TO SNOW OVERNIGHT. THE WESTERN PART OF THE
ZONE WILL SEE THE PRECIPITATION REMAIN SNOW. THIS PRECIPITATION WILL
SLOWLY SHUT OFF OVERNIGHT FROM THE WEST.

.LONG TERM FORECAST...
UPPER LEVEL FLOW CONTINUES TO EVOLVE INTO A MORE ZONAL PATTERN
ALLOWING A FEW MORE SYSTEMS TO TRAVEL QUICKLY THROUGH THE FORECAST
AREA WITHIN THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 125 138 140 141 150 155 160 165 170 172 175.
         STORM 130 132.
FIRE WEATHER...NONE.

EZ DEC 07