Small Craft Advisory 514, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
551 AM AKDT TUE SEP 11 2012

.SHORT TERM...THE FLAT SURFACE RIDGE WITH A SMALL SHARP AXIS NORTH
ALONG THE COAST MOUNTAINS. A COMPLEX AREA OF LOWER PRESSURE WITH
THE PARENT LOW SOUTH OF THE PRIBILOF ISLANDS HEADED SOUTHEAST. AN
OCCLUDED FRONT ARCS ACROSS THE BRISTOL BAY AREA TO A TRIPLE POINT
SOUTH OF KODIAK ISLAND. A WARM FRONT REACHES EAST AND SOUTHEAST
OVER THE CENTRAL GULF TUESDAY MORNING. THE COLD FRONT EXTENDS BACK
TO THE SOUTHWEST... SOUTH IT SEEMS THAT IS AT AT LEAST ON WAVE
ON THE FRONT BAND IN THE CENTRAL PACIFIC.

THE TRIPLE POINT LOW MOVES INTO THE NORTHEAST TUESDAY NIGHT... AND
THE HEAVIER RAINS ARE EXPECTING TO MOVE INTO THE PANHANDLE REGION
OVERNIGHT. EXPECTING A BROAD AREA OF SMALL CRAFT WINDS OVER THE
OUTER WATERS TUESDAY NIGHT... AND THINK THAT CLARENCE STRAIT WILL
CREEP UP INTO GALE LEVELS LATE TUESDAY NIGHT.

.HYDROLOGY...THE MOISTURE SOURCE REGION FROM MID TROPICS WILL BE
BRINGING QUITE A BIT OF WATER TO SOUTHEAST ALASKA STARTING TUESDAY
NIGHT. RAINFALL TOTALS OF 3 TO 6 INCHES WITH LOCALLY HEAVIER
AMOUNTS IS POSSIBLE TUE NIGHT THROUGH THU...WITH THE HIGHEST
RAINFALL IN THE CENTRAL AND SOUTHERN PANHANDLE. THE GROUND IS
ALREADY SATURATED SO THIS UPCOMING HEAVY RAIN MAY PUSH SOME RIVERS
AND STREAMS TO BANK FULL LEVELS OR HIGHER. INITIAL LOOK AT THE
STREAM AND RIVER LEVELS AND THE FORECAST FOR THEM SHOW THAT AT
THE MOMENT SIGNIFICANT FLOODING ISSUES ARE NOT EXPECTED. WITH ALL
OF THIS RAIN AND WET GROUND LANDSLIDES COULD BE POSSIBLE.

.LONG TERM...CURRENT LONG-WAVE PATTERN SHOWING A DEEP TROUGH OVER
THE BERING SEA AND THE EASTERN ALEUTIANS SUCKING IN SOME
IMPRESSIVE PRECIPITABLE WATER AMOUNTS ASSOCIATED WITH A SYSTEM
AROUND 30 N AND THE DATELINE. SOME VALUES ARE APPROACHING 200
PERCENT OF NORMAL, AND THIS BATCH OF MOISTURE WILL FUEL THE
SHORTWAVE STILL IN PLACE OVER THE PANHANDLE WEDNESDAY MORNING. AT
THIS POINT THOUGH THE LONGWAVE TROUGH OVER THE BERING SEA HAS
SHIFTED TO THE WESTERN GULF OF ALASKA AND THUS FLOW ALOFT BECOMES
PARALLEL TO SURFACE FRONT OVER CENTRAL ZONES AND THUS DECELERATES
ITS EASTWARD PROGRESSION TO A CRAWL OVER THE SOUTHERN ZONES. IN
FACT ANOTHER SHORTWAVE OVER THE SOUTHEASTERN GULF OF ALASKA
WEDNESDAY NIGHT WILL SPIN UP TO KINK MOISTURE PLUME A BIT BACK TO
THE CENTRAL ZONES FOR THURSDAY. FLOW FROM 500 DOWN TO THE SURFACE
IS MOSTLY ONSHORE SOUTHWEST WHICH IMPLIES A DEEP LEVEL OF MOISTURE
INDEED THAT BACKS UP THE POTENTIAL FOR HEAVY RAIN OVER THE CENTRAL
AND SOUTHERN ZONES THROUGH THURSDAY. WARM AIR ADVECTION
ACCOMPANIES THE MOISTURE PLUME TO ESPECIALLY KEEP SOUTHERN ZONES
WEDNESDAY NIGHT FROM COOLING MUCH FROM WEDNESDAY AFTERNOON HIGHS.
IN FACT, MOS SUGGESTING LITTLE TO NO DECREASE IN TEMPERATURE. IN
ADDITION, WINDS WILL PEAK AT SMALL CRAFT LEVELS FOR NORTHERN LYNN
AND GALE LEVELS ALONG CLARENCE STRAIT AS GRADIENTS TIGHTEN
WEDNESDAY MORNING. MEANWHILE THE COLD CORE LOW ALOFT WILL SPAWN
CONVECTIVE SHOWERS OVER YAKUTAT ON THURSDAY.

THURSDAY NIGHT FLOW BECOMES A LITTLE MORE ZONAL AS THE JUICY
SYSTEM PASSES EAST INTO INLAND BC. BOTH GFS AND EC BEGIN THE
WEEKEND WITH A RIDGE OVER THE EASTERN GULF AND THE PANHANDLE WITH
A DEEP TROUGH OVER THE ALASKA PENINSULA. THIS WILL LIKELY MEAN
ANOTHER SHORTWAVE AND ANOTHER ROUND OF PRECIPITATION, POTENTIALLY
HEAVY FOR SUNDAY AND SUNDAY NIGHT. SOME SORT OF ZONAL SOUTHWEST
FLOW FOLLOWS WITH CHANCES OF RAIN THROUGH THE MIDDLE OF NEXT WEEK.

CONFIDENCE FOR WEDNESDAY THROUGH THURSDAY IS PRETTY DECENT FOR
RAINFALL, BUT BEYOND EC AND GFS DIVERGE A LITTLE WITH THE DEEPNESS
OF THE LONGWAVE TROUGH OVER THE ALASKA PENINSULA SATURDAY NIGHT
WITH THE GFS DEFINITELY THE STRONGER OF THE TWO.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031>035-041>043-051-052.

&&

BEZENEK/JWA