Small Craft Advisory 349, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
604 AM AKDT THU MAY 19 2011

.SHORT TERM...EARLY MORNING SATELLITE LOOP REVEALS A LOW IN THE
FAR SOUTHERN GULF WITH ITS ASSOCIATED FRONTAL PASSAGE WRAPPING
AROUND THE LOW AND PROGRESSING NORTHWARD INTO THE NORTHERN GULF
AND ALSO NORTHEASTWARD INTO THE EASTERN GULF. A DISSIPATING
TROUGH EXTENDS SOUTHEASTWARD FROM SOUTHWESTERN YUKON TO THE
WESTERN BRITISH COLUMBIA. IN BETWEEN THESE TWO FEATURES...A
NARROW RIDGE OF HIGH PRESSURE REMAINS OVER SOUTHEAST ALASKA WITH
MULTI- LAYERED CLOUDINESS PREVAILING ACROSS THE NORTHERN TWO
THIRD OF THE PANHANDLE AND PARTLY CLOUDY SKIES ACROSS THE
SOUTHERN COASTAL AREAS. NO SIGNIFICANT WINDS/SEAS ARE REPORTED
EARLY THIS MORNING.

MODELS ARE IN GENERAL AGREEMENT WITH THE NARROW RIDGE OF HIGH
PRESSURE OVER SOUTHEAST ALASKA WEAKENS THROUGH LATE TONIGHT AS THE
FRONTAL PASSAGE MOVES INTO THE EASTERN GULF. REFRESHED THE
INHERITED GRIDS WITH THE NAM AND GFS FRO TODAY AND TONIGHT. THE
FRONT WILL CONTINUE TO MARCH NORTHEASTWARD AND MOVE ONSHORE OVER
THE IMMEDIATE PANHANDLE COAST TONIGHT. ALONG WITH THE FRONTAL
BOUNDARY...GALE FORCE WINDS ARE EXPECTED ACROSS THE OFFSHORE
WATERS THIS AFTERNOON. THE GALE WILL ALSO AFFECT THE NORTHERN MOST
OUTSIDE WATERS THROUGH EARLY TONIGHT. SOLID SMALL CRAFT WINDS AND
ROUGH SEAS ARE EXPECTED FOR THE REST OF THE OUTER WATERS. NO
SIGNIFICANT WINDS ARE EXPECTED ACROSS THE INNER CHANNELS.

THE WEAKENING RIDGE WILL CONTINUE TO MAINTAIN WEAK SOUTHERLY
PRESSURE GRADIENT ACROSS THE PANHANDLE. ALONG THE FRONTAL
BOUNDARY...EAST TO SOUTHEAST WINDS WILL INCREASE THROUGH TONIGHT.
THE FRONT...AS IT APPROACHES THE PANHANDLE COAST...WILL WEAKEN AND
BEGIN DISORGANIZE BY LATE TONIGHT BEFORE MOVING FARTHER INLAND.
LIKELY TO CATEGORICAL POPS WILL SPREAD ALONG THE NORTHERN AND
CENTRAL PANHANDLE COASTAL SECTIONS TONIGHT. THE LOW IN THE FAR
SOUTHERN GULF WILL BECOME BROAD OVER THE WESTERN GULF THIS EVENING
THEN OPEN FOR ANOTHER DEVELOPING LOW SOUTH OF THE ALEUTIANS LATE
TONIGHT.

&&

.LONG TERM...A NEGATIVLY TILTED UPPER LEVEL TROUGH EXTENDING FROM
KODIAK TO VANCOUVER WILL PERSIST OVER THE WEEKEND BEFORE SHEARING
APART. THE FRONT ALONG THE IMMEDIATE COAST OF SOUTHEAST ALASKA
BECOMES STATIONARY AND BEGINS TO SHEAR APART ON FRIDAY AS A WAVE
ALONG THE FRONT PROPAGATES NORTH. FRONT BEGINS TO PULL BACK TO THE
NW ON SATURDAY AS A NARROW RIDGE BUILDS INTO THE EASTERN GULF FROM
THE S. A NEW UPPER LOW MOVES EAST ALONG 50N MONDAY THROUGH THURSDAY
WITH EASTERLY FLOW ACROSS THE PANHANDLE.

IN GENERAL EXPECTING CLOUDS BUT LIMITED RAIN INTO THE EARLY
WEEKEND. PAYA WILL BE THE EXCEPTION AS IT HAS TO BETTER SLY FLOW
WITH HIGHER PRECIPITABLE WATER. SMCR IN THE COASTAL WATERS
DIMINISH AND FALL BELOW SMCR BY FRIDAY NIGHT. DOWNSLOPE ESE WINDS
SHOULD LIMIT PRECIP FOR INNER CHANNELS. STILL KEPT A CHANCE OF
LIGHT RAIN FOR INNER CHANNELS FRI WITH LIKELY POPS ALONG THE
COAST. AS FRONT SHEARS APART AND RETROGRADES SHOULD ALLOW A LITTLE
DRIER CONDITIONS SATURDAY UNTIL A DISTURBANCE IN EASTERLY FLOW
ARRIVES SATURDAY NIGHT. AS RIDGE BUILDS INTO EASTERN GULF
GRADIENTS WEAKEN AND WIND DROP OFF TO 15 KT OR LESS.

OFFSHORE FLOW SETS UP EARLY NEXT WEEK WITH POPS DROPPING TO LESS
THAN 20 PERCENT BY TUESDAY. WITH INCREASED SUNSHINE TEMPS WARM
INTO THE LOWER 60S FOR INNER CHANNELS HOWEVER COOLER ALONG THE
COAST WITH SEA BREEZE.

OVERALL CONFIDENCE IS BELOW NORMAL WITH RUN TO RUN VARIATIONS ON
FAR FRONT WILL PENETRATE INTO SOUTHEAST ALASKA. IN GENERAL SE
WINDS ALOFT FAVOR CLOUDS WITH LITTLE PRECIP SO LEANED TO DRIER NAM
FOR FRI AND SAT. GFS AND EC HAVE INTENSITY DIFFERENCES WITH SECOND
SYSTEM MOVE EAST ALONG 50N BUT THE DIFFERENCES DO NOT SEE TO
AFFECT THE PANHANDLE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ052 PKZ310.
         SMALL CRAFT ADVISORY FOR PKZ041>043-051-053.

&&

AHN/MM