Small Craft Advisory 311, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
323 PM AKDT THU MAY 10 2012

.SHORT TERM...A FRONTAL SYSTEM ASSOC WITH A LOW OVER THE ALASKA
PENINSULA WILL BE THE MAIN WEATHER FEATURE THROUGH THE SHORT TERM
PERIOD. THE WARM FRONT IS CURRENTLY OVER THE EASTERN GULF AND HAS
BEEN GIVING MODERATE RAIN TO THE YAKUTAT AREA AND LIGHT RAIN
ELSEWHERE TODAY. WINDS ARE EXPECTED TO INCREASE TO GALE FORCE
ALONG THIS FRONT FOR THE OUTSIDE WATERS THIS EVENING. WINDS WILL
ALSO INCREASE FOR THE INSIDE WATERS OVERNIGHT WITH MANY LOCATIONS
REACHING GALE FORCE INTO FRIDAY. HAVE INCREASED WINDS TO THIS
MAGNITUDE TO ACCOUNT FOR THE EXPECTED 850MB WINDS OF 40 TO 50KT
AS WELL AS THE STRONG SOUTHERLY PRESSURE GRADIENT. HEAVIEST
RAINFALL WITH THE WARM FRONT WILL BE MAINLY OVER THE NORTHERN
COASTAL AREAS...YAKUTAT REGION TONIGHT AND CLOSER TO THE CROSS
SOUND AREA FRIDAY. RAINFALL AMOUNTS OF 1 TO 2 INCHES CAN BE
EXPECTED THROUGH FRIDAY AFTERNOON.

MODELS HAVE HAD A GOOD HANDLE ON THIS SYSTEM OVER THE PAST
SEVERAL DAYS AND HAVE BEEN IN GOOD AGREEMENT AS WELL. UPDATED THE
GOING FORECAST WITH A BLEND DUE TO THE GOOD CONSENSUS WITH AN
EMPHASIS ON THE MESOSCALE MODELS FOR THEIR DETAIL. FORECASTER
CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...AN ACTIVE START TO THE PERIOD WITH HEAVY RAINFALL
AND STRONG WIND CONTINUING FOR MUCH OF THE PANHANDLE. THE MAIN
FEATURE THROUGH THE WEEKEND WILL BE THE AFOREMENTIONED OCCLUDED
FRONT SLOWLY MOVING ACROSS THE AREA LATE FRIDAY NIGHT AND
LINGERING ACROSS THE SOUTHERN PANHANDLE INTO LATE SATURDAY. UPPER
LEVEL RIDGING WILL SHIFT EASTWARD INTO CANADA. BEHIND THIS
FRONT...A SHORTWAVE TROUGH WILL DROP SOUTH INTO THE GULF ON SUNDAY
AND INDUCE A WEAK SURFACE WAVE. THIS WILL MOVE ACROSS THE NORTHERN
PANHANDLE EARLY TUESDAY WITH HIGH PRESSURE BUILDING IN MID WEEK.

SHORTWAVE/VORT MAX ROUNDING THE BASE OF THE TROUGH IN THE GULF AND
ASSOCIATED SURFACE LOW WILL TRACK NORTH INTO THE VICINITY OF
PRINCE WILLIAM SOUND BY SATURDAY MORNING. THIS WILL SHARPEN THE
SURFACE RIDGE OVER THE PANHANDLE LEADING TO CONTINUED GUSTY
SOUTHERLY WINDS FRIDAY NIGHT INTO SATURDAY. GUSTS TO 40 MPH CAN
BE EXPECTED ACROSS MOST LAND AREAS WITH GALE WARNINGS ACROSS MUCH
OF THE COASTAL ZONES AND INSIDE WATERS. WINDS WILL DIMINISH IN
MOST AREAS SATURDAY AFTERNOON WITH THE FRONTAL PASSAGE. SOUTHERN
AREAS WILL SEE WINDS LINGER INTO THE NIGHT BEFORE SUBSIDING. THE
CENTRAL AND NORTHERN PANHANDLE WILL BE LOCATED IN THE FAVORABLE
LEFT EXIT REGION OF THE UPPER LEVEL JET LEADING TO HEAVY RAINFALL
AMOUNTS. YAKUTAT CAN EXPECT TO SEE 4-6" OF RAIN WITH AMOUNTS
DECREASING TO THE SOUTH AND EAST. JUNEAU IS EXPECTED TO SEE 1-3"
THROUGH SATURDAY NIGHT.

SHORTWAVE TROUGH IN THE GULF AND ONSHORE FLOW WILL KEEP SHOWERS IN
THE FORECAST SUNDAY THROUGH TUESDAY. HIGHEST COVERAGE OF SHOWERS
LOOKS TO BE IN THE NORTHERN PANHANDLE. SHOWERS DIMINISH LATER
TUESDAY AS THE TROUGH LIFTS NORTHEAST. THERE ARE INDICATIONS OF A
POTENTIAL PATTERN CHANGE THE MIDDLE OF NEXT WEEK WITH RIDGING
ACROSS THE GULF BUILDING EAST INTO THE AREA. THIS WOULD BRING
WARMER AND DRIER CONDITIONS FOR THE LATTER HALF OF THE WEEK.

MAINLY FOCUSED ON THE GRIDS THROUGH SUNDAY WITH A BLEND OF THE
EC/GFS. DID DEEPEN THE LOW TRACKING NORTH IN THE GULF ON
SATURDAY. FORECASTER CONFIDENCE BEGINS ABOVE AVERAGE ON A HEAVY
RAIN AND STRONG WIND EVENT THE FIRST HALF OF THE WEEKEND AND
DECREASES THE MIDDLE OF NEXT WEEK WITH THE POTENTIAL PATTERN
CHANGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 1 AM AKDT FRIDAY THROUGH FRIDAY EVENING FOR
     AKZ022.
         STRONG WIND FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR
     AKZ023.
         STRONG WIND FROM 7 PM TO 10 PM AKDT THIS EVENING FOR AKZ018.
         STRONG WIND FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR
     AKZ018.
         STRONG WIND FROM 1 AM AKDT FRIDAY THROUGH FRIDAY MORNING FOR
     AKZ017.
MARINE...GALE WARNING FOR PKZ012-013-021-022-031>036-041>043-051>053.
         SMALL CRAFT ADVISORY FOR PKZ011.

&&

HANNON/TPS/MM