Small Craft Advisory 709, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 AM AKDT TUE SEP 16 2008

.ANALYSIS AND UPPER LEVELS...
MAIN FEATURE OF INTEREST THIS MORNING IS A 994 MB SURFACE LOW
PRESSURE MOVING NORTH THROUGH THE WESTERN GULF OF ALASKA. COPIOUS
RAIN SURROUNDS THE LOW ALONG WITH WINDS TO GALE FORCE OVER THE GULF.
A WARM FRONT EXTENDS OUT AHEAD AND NORTH OF THE LOW AND IS SPREADING
RAIN INTO SOUTHCENTRAL. THE LOW MOVES NORTH INTO PRINCE WILLIAM
SOUND EARLY WEDNESDAY.

COMPLEX SETUP OUT WEST THIS MORNING...WITH A DEVELOPING TRIPLE POINT
LOW SOUTH OF ADAK...A WEAK LOW IN THE CENTRAL BERING...AND AN OLD
WEAK VERTICALLY STACKED LOW ALONG THE SOUTHWEST COAST. THE TRIPLE
POINT LOW SOUTH OF ADAK WILL BECOME THE DOMINANT LOW OUT WEST AS IT
IS IN THE MOST FAVORABLE POSITION WITH REGARDS TO THE JET STREAM
OVER THE ALEUTIANS.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT OUT WEST THROUGH THE SHORT TERM. IN THE
EAST...0Z MODELS ARE IN GOOD AGREEMENT FOR THE CURRENT LOW IN THE
GULF AND ITS MOVEMENT INTO PRINCE WILLIAM SOUND...BUT ARE HAVING A
BIT MORE TROUBLE WITH THE NEXT LOW. MODELS ARE JUST NOW COMING INTO
BETTER...BUT STILL NOT PERFECT...AGREEMENT WITH THE NEXT LOW AS IT
MOVES EAST TOWARD KODIAK LATE WEDNESDAY NIGHT. RUN TO RUN
CONSISTENCY HAS BEEN POOR WITH ALL MODELS. 0Z RUNS HAVE CONVERGED TO
TRACK THE LOW NEAR OR OVER KODIAK ISLAND THURSDAY...AND QUITE STRONG
TO AROUND 980 MB. 0Z GFS RUNS HAVE BEEN HAVING THE SAME LOCATION
WITH THIS LOW FOR A COUPLE DAYS NOW (OVER KODIAK)...WHILE ALL 12Z
GFS RUNS INTERESTINGLY HAVE HAD A DIFFERENT SOLUTION (BRISTOL
BAY)...JUST AN EXAMPLE OF THE WACKY MODEL BEHAVIOR.

.SHORT TERM FORECAST...
SOUTHCENTRAL/SOUTHWEST MAINLAND...
A 994 MB GALE FORCE LOW IS MOVING NORTH THROUGH THE GULF TODAY AND
WILL MOVE INTO PRINCE WILLIAM SOUND EARLY WEDNESDAY. UNLIKE SOME
PREVIOUS SYSTEMS...THIS ONE WILL EASILY SPREAD RAIN OVER THE KENAI
AND CHUGACH MOUNTAINS TO INLAND AREAS. RAIN HAS ALREADY BEGUN FROM
HOMER TO ANCHORAGE AND WILL CONTINUE OFF AND ON THROUGH TOMORROW
MORNING. IF IT WERE A MONTH LATER...THIS WOULD BE A GOOD SETUP FOR
SNOW OVER INLAND SOUTHCENTRAL...BUT NOT QUITE YET. MOST OF THE
PRECIPITATION WITH THIS SYSTEM WILL REMAIN ALONG AND EAST OF THE
ALASKA/ALEUTIAN RANGE...WITH JUST SOME SCATTERED SHOWERS AND FOG
OVER THE SOUTHWEST MAINLAND.

MEANWHILE...ANOTHER LOW WILL BE RIDING ALONG JUST SOUTH OF THE
ALEUTIANS STRENGTHENING ALL ALONG. THIS LOW WILL REACH KODIAK ISLAND
AROUND THURSDAY MORNING AS A FAIRLY STRONG LOW. THE BREAK BETWEEN
THE WEATHER ASSOCIATED WITH THIS LOW AND THE FIRST LOW WILL BE VERY
BRIEF...AS HAS OFTEN BEEN THE CASE LATELY. THE SECOND LOW HAS A
BETTER CHANCE OF SPREADING RAIN INTO THE SOUTHWEST MAINLAND THAN THE
FIRST LOW.

BERING SEA/ALEUTIANS...
A TRIPLE POINT LOW DEVELOPING SOUTH OF ADAK THIS MORNING WILL RIDE
JUST SOUTH OF THE ALEUTIANS AND ALASKA PENINSULA...STRENGTHENING ALL
ALONG. A WEAK LOW IN THE CENTRAL BERING MOVING TOWARD THE PRIBILOFS
WILL DISSIPATE AND BE ABSORBED INTO THE STRONGER ABOVE MENTIONED LOW
TUESDAY NIGHT. NORTHWEST FLOW WILL THEN DOMINATE THE CENTRAL TO
EASTERN BERING/ALEUTIANS THROUGH THURSDAY.

.LONG TERM FORECAST...
FOR THE EXTENDED...GENERALLY SPEAKING...IT APPEARS THAT THE LOW OVER
THE WESTERN GULF OR KODIAK ISLAND WATERS WILL BE GRADUALLY WEAKEN
BUT BE SLOW TO EXIT THE REGION...PERHAPS EVENTUALLY MOVING OUT WITH
HIGH PRESSURE BUILDING INTO THE MAINLAND LATE SUNDAY OR MONDAY. IT
DOES LOOK LIKE NORTHWEST FLOW OVER THE SOUTHWEST MAINLAND WILL USHER
IN THE COOLEST AIRMASS OF THE SEASON SO FAR FRIDAY AND INTO THE
WEEKEND. HIGH PRESSURE APPEARS TO SETUP OVER THE EASTERN BERING WITH
WEST TO SOUTHWEST FLOW OVER THE WEST/CENTRAL BERING/ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING ZONES 120 130 132 150 155 170 351.
FIRE WEATHER...NONE.

FOISY SEP 08