Small Craft Advisory 905, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM ADT SAT OCT 27 2007

.ANALYSIS AND UPPER LEVELS...THE STATE REMAINS UNDER AN UPPER LEVEL
LONG WAVE TROUGH. THERE IS A WEAK UPPER LEVEL CENTER OVER THE ALASKA
PENINSULA THAT HAS A SUMER OF SHORT WAVES ROTATING AROUND IT BRINGING
SHOWERS INTO KODIAK ISLAND...SOUTHERN COOK INLET...AND INTO THE
NORTHERN PART OF THE BRISTOL BAY ZONE.
A SURFACE LOW SOUTHWEST OF KODIAK ISLAND WILL ALSO BRING A FEW MORE
SHOWERS INTO THE KODIAK AREA THIS EVENING AND OVERNIGHT AS IT MOVES
NORTH OF THE ISLAND AND THEN DISSIPATES SUNDAY.
A LOW IN THE WESTERN BERING SEA WILL MERGE WITH A LOW DEVELOPING IN
THE PACIFIC JUST EAST OF DUTCH HARBOR SUNDAY EVENING. THIS LOW WILL
BECOME A BIG WEATHER MAKER.
THERE WAS A TROPICAL STORM NAMED FAXAI OFF THE COAST OF JAPAN THAT
HAS NOW WEAKENED AND THE JET STREAM ASSOCIATED WITH IS MOVING
EASTWARD SPAWNING A NEW LOW. THIS JET STREAM IS QUITE IMPRESSIVE WITH
ITS TROPICAL CONNECTION IN THAT IT IS DIRECTLY LINKED INTO A STRONG
LOW IN THE PHILIPPINES. THIS JET STREAM IS CLEARLY SEEN ON THE
COMPOSITE IR SATELLITE LOOKING AT THE WESTERN PACIFIC. THIS DIRECT
TROPICAL FEED INTO THE REMNANTS OF THE FORMER TROPICAL STORM IS WHAT
IS MOST LIKELY CAUSING THE GREAT CONFUSION IN THE WEATHER MODELS.
MORE ON THIS IN THE NEXT SECTION. WHAT IS FAIRLY CERTAIN IS THAT THIS
REDEVELOPING SYSTEM WILL MERGE WITH THE BERING SEA LOW SUNDAY EVENING
AND THEN BE A STRONG LOW THAT MOVES INTO THE MIDDLE OF THE FORECAST
AREA.

.MODEL DISCUSSION...IN THE NEAR TERM THE MODELS ARE DOING WELL.
THROUGH SUNDAY AFTERNOON ANY ONE OF THE MAJOR FOUR CAN BE USED WITH A
FAIRLY HIGH DEGREE OF CONFIDENCE. IT WI WHEN THE EXTRA-TROPICAL
SYSTEM MOVES IN THAT THEY COME APART. THE MODELS ARE NOTORIOUSLY BAD
AT RESOLVING EXTRA-TROPICAL SYSTEMS...ESPECIALLY THE AMOUNT OF DEEP
MOISTURE AND WARM AIR THAT IS ASSOCIATED WITH THEM. THE ECMWF AND THE
GFS HAD QUITE DIFFERENT SOLUTIONS YESTERDAY AND NOW THEY ARE STILL
DIFFERENT BUT EACH ONE NOW HAS THE APPROXIMATE SOLUTION THE OTHER ONE
HAD YESTERDAY FOR THE MONDAY NIGHT THROUGH TUESDAY FORECAST PERIODS.
THEREFORE THERE IS NOT A HIGH DEGREE OF CONFIDENCE IN ANY ONE MODEL
SOLUTION. HOWEVER LOOKING AT WHAT IS LIKELY TO HAPPEN WITH THIS
APPROACHING SYSTEM THERE IS A REASONABLE SOLUTION THAT CAN BE COME UP
WITH.
WHAT I LIKE ABOUT THE ECMWF SOLUTION IS THAT IT IS THE STRONGEST OF
THE MODELS WITH THE LOW. THE LOW WILL LIKELY BE STRONG DUE TO ITS
HISTORY OF BEING A TROPICAL STORM AND THE CONTINUED TROPICAL
CONNECTION.IT ALSO KEEP STRENGTHENING THE LOW AS COLDER AIR FROM THE
BERING SEA IS PUMPED INTO IT. HOWEVER I DO NOT LIKE THE TRACK ON IT.
IT IS BEING KEPT SOUTH OF THE ALEUTIAN ISLANDS AND THEN CONTINUES
INTO THE GULF OF ALASKA. THIS SEEMS QUITE SUSPECT DUE TO THE UPPER
LEVEL SUPPORT. WITH THIS LOW MERGING WITH THE LOW IN THE BERING SEA
AND THE JET STREAM PUSHING EASTWARD...THE ENERGY IN THE SYSTEM SHOULD
CONTINUE TO MOVE FORWARD AND NOT DEVELOP IN A WAVE SOUTH OF THE
ALEUTIAN ISLANDS. ALSO AS THE LOW STRENGTHENS IT WILL NATURALLY WANT
TO CURVE A LITTLE MORE TO THE LEFT WHICH IS WHAT BOTH THE GFS AND
UKMET MODELS ARE SHOWING. THE UKMET AND GFS HOWEVER LOOK TO BE MUCH
TOO WEAK. THEREFORE THE BASIC THINKING IN TODAYS IS THAT THE TRACK
WILL BE SIMILAR TO THE GFS SOLUTION THAT WILL BRING IT ON SHORE IN
THE UPPER PART OF BRISTOL BAY. UKMET BRINGS IN INTO LOWER COOK INLET.
EITHER WAY THE STRENGTH WILL BE MUCH DEEPER THAT WITHER THE GFS OR
UKMET IS SHOWING.

.SHORT TERM FORECAST...SOUTH TO SOUTHEAST FLOW IN THE UPPER LEVELS
WILL KEEP SOME  SHOWERS IN SOUTH CENTRAL AND SOUTHWEST ALASKA THROUGH
SUNDAY. CLEARING SKIES IN THE COPPER RIVER BASIN WILL ALLOW RADIATION
FOG TO DEVELOP AGAIN OVERNIGHT. PARTS OF THE SUSITNA VALLEY AND
KUSKOKWIM VALLEY WILL BE SUSCEPTIBLE TO THIS AS WELL. A FRONTAL BAND
BETWEEN THE AIRMASS IN THE BERING SEA AND THE PACIFIC LOW WILL BRING
RAIN TO THE ALEUTIAN ISLANDS TONIGHT AND TOMORROW.

.LONG TERM FORECAST...THE BERING SEA AND SOUTHWEST ALASKA WILL BE ON
THE COLD ADVECTION BACK END OF THE BIG LOW AS IT MOVES THROUGH NEXT
WEEK. THE FAR EASTERN PART OF THE AREA WILL BE ON THE WARM ADVECTION
SIDE. IN BETWEEN WILL DEPEND ON THE EXACT TRACK AND STRENGTH OF THE
LOW AS IT HEADS INTO THE AREA. SEE THE MODEL FORECAST SECTION FOR
MORE DETAILS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 150 160 165 171 175 176.
         STORM 155 170 172.
FIRE WEATHER...NONE.

OCT 07