Small Craft Advisory 497, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
338 PM AKDT SAT AUG 27 2011

.SHORT TERM... A LOW PRESSURE SYSTEM WILL MOVE INTO THE CENTRAL
GULF THROUGH THE PERIOD. A FRONTAL TROUGH ASSOC WITH THIS LOW IS
CURRENTLY OVER THE EASTERN GULF AND WILL MOVE INTO THE PANHANDLE
THIS EVENING...BRINGING WIDESPREAD RAIN TO THE AREA. RAIN SHOWERS
TONIGHT MAY BECOME HEAVY AT TIMES WITH SOME GUSTY SOUTHEASTERLY
WINDS. HIGHEST WINDS WILL BE ALONG THE GULF COAST AND THE SWRN
PANHANDLE. OFFSHORE WINDS WILL INCREASE TO 30KT WITH SEAS AROUND
8-10FT. AS THE LOW INCREASES THE PRESSURE GRADIENT OVER THE
AREA...EXPECT SMALL CRAFT LEVEL WINDS FOR INSIDE WATERS EXPOSED
TO THE OCEAN AND SOUTHERLY WINDS THROUGH CHATHAM STRAIT. FURTHER
INLAND A RIDGE WILL BE PUSHED INTO CANADA...CAUSING LIGHT WINDS
TO INCREASE OUT OF THE NORTH THROUGH LYNN CANAL.

RAINFALL WILL CONTINUE THROUGH SUNDAY...WITH HEAVIER BURSTS AS
UPPER LEVEL SHORT WAVES PASS OVERHEAD. THESE WILL BE MOST
PREVALENT OVER THE SOUTHERN HALF OF THE PANHANDLE AS THE SURFACE
AND UPPER LEVEL LOW MOVES INTO THE EASTERN GULF BEGINS TO TURN
SOUTH. AS A RESULT THE FAR NORTHERN AREA WILL START TO SEE
RAINFALL ACTIVITY EASE AS MID-LEVEL FLOW TURNS SLIGHTLY OFFSHORE.

MODELS HAVE BEEN IN GOOD AGREEMENT WITH THIS SYSTEM. USED AN
ENSEMBLE APPROACH TO UPDATE THE GOING FORECAST...WITH AN EMPHASIS
ON THE NAM12 AND EC WHICH INITIALIZED OVER THE PANHANDLE WELL.

.LONG TERM...UPPER LOW MOVES ACROSS CENTRAL SOUTHEAST ALASKA
SUNDAY NIGHT INTO EARLY MONDAY AND EXITS TO THE ESE MONDAY
AFTERNOON. WEAK SURFACE RIDGE BUILDS INTO THE EASTERN GULF MONDAY
NIGHT AND SHIFTS EAST ACROSS THE PANHANDLE THROUGH WEDNESDAY.
UPPER RIDGE IS FAIRLY FLAT WITH WESTERLY FLOW OVER THE PANHANDLE.
NEXT FRONT MOVES TO COAST WEDNESDAY NIGHT AND DISSIPATES OVER
SOUTHEAST ALASKA THURSDAY.

RAIN CONTINUING ACROSS SOUTHEAST ALASKA SUNDAY NIGHT. SCATTERED
SHOWERS DECREASE FROM THE NORTHWEST ON MONDAY AND EXIT THE
SOUTHEAST CORNER BY LATE MONDAY NIGHT. OVERALL AMOUNTS IN LIGHT
CATEGORY. HAVE TUE DRY AS RIDGE MOVES ACROSS THE AREA BUT KEPT
SKIES MOSTLY CLOUDY XCP FOR PAYA. NEXT FRONT SPREADS RAIN BACK INTO
THE PANHANDLE WEDNESDAY NIGHT WHICH CONTINUES THROUGH THURSDAY.

WIND DIMINISH SUNDAY EVENING AND STAY BELOW SMCR LEVELS THROUGH
TUE ALTHOUGH A 6-8 FOOT SW SWELL PERSISTS. NW WIND INCREASES ON
WEDNESDAY IS SE GULF AND BECOME SOUTHWEST 25 KT OVER GULF BY WED
NIGHT. MODELS HINTING A SHIFT TO NORTH WINDS FOR INNER CHANNELS LATE
IN THE WEEK AND WEEKEND.

HAD GOOD MODEL AGREEMENT THROUGH 84 HRS THEN MODELS STRONGLY
DIVERGE WITH A SYSTEM IN THE BERING AND A RAPIDLY DEEPENING
SYSTEM IN WESTERN GULF BY DAY 8. OPTED TO MAKE NO CHANGES BEYOND
84 HRS DUE TO LOW CONFIDENCE. IN THE EARLIER PERIOD USED 12Z NAM
12 FOR GRIDS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ021-022-032>036-041>043-051-052.

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HANNON/MM