Small Craft Advisory 853, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
600 AM AKDT WED OCT 30 2013

.ANALYSIS AND UPPER LEVELS...THE DOMINANT FEATURE IN THE AREA THIS
MORNING IS THE DEVELOPING AREA OF LOW PRESSURE RIGHT OVER TOP OF
KODIAK ISLAND. THE SYSTEM IS RIDING ALONG THE FAVORED LEFT EXIT
REGION OF A 130 KT JET THAT IS POINTED FROM SW TO NE RIGHT AT
SANDSPIT B.C. IT WILL PULL AWAY FROM THE JET LATER TODAY AND START TO
SLOWLY WEAKEN AS IT DRIFTS TOWARDS THE PRINCE WILLIAM SOUND. THE
LONGWAVE TROUGH REMAINS CENTERED ON THE BERING WITH WEAK SHORTWAVE
RIDGING OVER THE EASTERN HALF OF THE MAINLAND. ONE MORE WEAK LOW IS
APPROACHING THE WESTERN ALEUTIANS WITH MARGINAL UPPER LEVEL SUPPORT.

.MODEL DISCUSSION...MODELS HAVE FINALLY COME INTO GOOD AGREEMENT THIS
MORNING. THE 00Z NAM WAS ABOUT 100 MI TOO FAR EAST WITH THE
PREVIOUSLY MENTIONED LOW AND TOO WEAK. THE 06Z RUN CORRECTED THESE
ISSUES AND IT WAS USED IN PART FOR ITS RESOLUTION ALONG WITH THE MORE
STABLE ECMWF IN THIS FORECAST PACKAGE. THE TIGHT MODEL CLUSTER LEADS
TO HIGH FORECAST CONFIDENCE THROUGH THE FIRST 48 HRS OR SO.

BEYOND THAT...THERE ARE SOME DIFFERENCES IN HOW THE MODELS HANDLE AN
UPPER LEVEL TROUGH DROPPING OVER THE AK RANGE INTO SOUTHCENTRAL LATE
FRIDAY. THE GFS IS THE WEAKEST WITH THIS FEATURE WHILE THE EC IS THE
MOST AGGRESSIVE. WITH SOME LINGERING MOISTURE IN THE LEFTOVER
DEFORMATION ZONE FROM THE LOW IN THE GULF...THIS TROUGH COULD PROVIDE
ENOUGH LIFT AND COLD AIR ADVECTION TO PULL SOME RAIN MIXED WITH SNOW
AWAY FROM THE MOUNTAINS TOWARDS THE ANCHORAGE BOWL LATE FRIDAY AND
SATURDAY MORNING. AFTER THAT...MODELS HAVE TRENDED TOWARDS A MORE
PROGRESSIVE SOLUTION. SEVERAL MORE SYSTEMS WILL LINE UP IN THE QUEUE
OVER THE BERING AND MOVE TOWARDS THE MAINLAND WITH ON AGAIN OFF AGAIN
WET AND WINDY WEATHER.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...SE WINDS WILL CONTINUE TO BE GUSTY THIS MORNING
AS THE LOW MOVES TOWARDS THE PRINCE WILLIAM SOUND. THE LOW WILL START
TO FILL BY EARLY AFTERNOON...SO GRADIENTS SHOULD PEAK OVER THE NEXT
FEW HOURS. WINDS WILL THEN SLOWLY DIMINISH THROUGH THE DAY. MOST OF
THE PRECIPITATION WITH THIS SYSTEM WILL BE CONFINED TO COASTAL AREAS.
AMOUNTS WILL BE SIGNIFICANTLY LESS THAN WHAT WE'VE SEEN FROM THE PAST
FEW SYSTEMS.

THE LOW WILL WEAKEN AS IT MOVES ONSHORE IN THE PRINCE WILLIAM SOUND
LATE THURSDAY. THIS WILL LEAVE MUCH OF THE AREA UNDER WEAK FLOW WITH
PLENTY OF CLOUD COVER BUT NOT MUCH PRECIPITATION BESIDES A FEW
MOUNTAIN SHOWERS. THIS SHOULD MAKE FOR A MILD AND RELATIVELY DRY
EVENING FOR THOSE WITH HALLOWEEN INTERESTS.

SOUTHWEST ALASKA...THINGS WILL REMAIN QUITE WET FOR MUCH OF THE AREAS
INLAND FROM BRISTOL BAY THIS MORNING AS THE LOW WRAPS MOISTURE
AROUND. AS IT MOVES FURTHER EAST TODAY...A DRYING TREND SHOULD SLOWLY
BEGIN. SOME DECENT PRESSURE RISES WILL LEAD TO GUSTY NORTHWEST WINDS
THROUGH THE EASTERN ALEUTIANS INTO THE ALASKA PENINSULA. A BRIEF BUT
POTENT SHORTWAVE RIDGE WILL BRING A WELCOME BREAK IN THE WET AND
WINDY WEATHER ON FRIDAY BEFORE THE NEXT SYSTEM APPROACHES ON
SATURDAY.

BERING SEA AND ALEUTIAN ISLANDS...RELATIVELY QUIET WEATHER WILL
CONTINUE TODAY AND THURSDAY WITH GENERALLY BROAD WESTERLY FLOW. THE
NEXT SYSTEM...ANOTHER TYPHOON REMNANT...WILL BRING MORE GALES AND
RAIN IN FROM THE SOUTHWEST ON FRIDAY. THIS SYSTEM WILL TRACK THROUGH
THE ALEUTIANS AND PARK ITSELF IN THE CENTER OF THE BERING BY MIDDAY
SATURDAY.

.LONG TERM FORECAST...THE LONG RANGE GLOBAL MODELS ARE NOT
ADVERTISING ANY MAJOR CHANGE TO THIS PATTERN OVER THE NEXT WEEK.
OCCASIONAL WET AND WINDY SYSTEM WILL CONTINUE TO MOVE QUICKLY FROM
WEST TO EAST. THERE IS SOME HINT...ALBEIT SMALL...OF A MORE AMPLIFIED
PATTERN IN THE MIDDLE OF NEXT WEEK. SOME COLDER... MORE SEASONAL AIR
CREEPING IN FROM THE NORTHWEST COULD SEND OUR TEMPERATURES MORE
TOWARDS NORMAL. BUT THIS AMPLIFIED PATTERN LOOKS LIKE IT COULD ALSO
BRING A STRETCH OF DRY WEATHER TO MUCH OF THE STATE AS WELL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING 119 120 125 130 131 132 138 139 150 351 352.
FIRE WEATHER...NONE.

MSO OCT 13