Small Craft Advisory 259, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
555 AM AKDT WED APR 18 2012

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOWS A WEAKENING LOW
PRESSURE SYSTEM SW OF HAIDA GWAII WITH CLOUDS LIFTING OVER THE
PANHANDLE. NO STATIONS ATTM ARE REPORTING ANY PRECIP WITH THE LOW
WEAKENING AND UPPER LEVEL FLOW FROM THE ESE TO KEEP THE AREA ON
THE DRY SIDE. WINDS ARE ON THE LIGHT SIDE THIS MORNING WITH A
WEAK PRESSURE GRADIENT. THE STRONGEST WINDS ARE OVER THE MARINE
WATERS WITH NORTH WINDS TO 20 TO 15KT OVER THE INNER CHANNELS AND
MIN SMALL CRAFT OVER THE SE GULF.

 AS THE SURFACE LOW WEAKENS AND DRIFTS TO THE NW THROUGH TODAY
THE UPPER LEVEL TROF ASSOCIATED WITH THE LOW WILL LIFT NORTH OVER
THE SOUTHERN PANHANDLE THIS AFTERNOON AND ACROSS THE CENTRAL
AREAS TONIGHT. THIS UPPER LEVEL DYNAMICS WILL AND INCREASING
ONSHORE FLOW FROM THE SOUTH WILL ALLOW LIGHT RAIN TO DEVELOP OVER
THE FAR SOUTHERN AREAS THIS AFTERNOON AND PERSIST THROUGH
TONIGHT. THE CENTRAL AREAS WILL SEE THE RAIN DEVELOP THROUGH
TONIGHT AS THE UPPER LEVEL SUPPORT LIFTS NORTH. THE NORTH CENTRAL
AREAS WILL SEE JUST A CHANCE TONIGHT AND THE FAR NORTHERN AREAS
AND NORTHER GULF COAST WILL REMAIN ON THE THE DRY SIDE THROUGH
THE NEXT 24HRS.

 CLOUD COVER OVER THE SOUTHERN AREAS WILL REMAIN ON THE CLOUDY
SIDE BUT THE NORTHER HALF WILL SEE PARTLY SUNNY SKIES WITH LARGE
BREAKS IN THE CLOUD COVER. THE CLOUDS WILL INCREASE LATE THIS
AFTERNOON INTO TONIGHT AS THE UPPER LEVEL TROF LIFTS NORTH OVER
THE PANHANDLE.

 THE WINDS WILL REMAIN ON THE LIGHT SIDE FOR THE MOST PART WITH
NOT MUCH OF A PRESSURE GRADIENT OVER THE INNER CHANNELS. THE
SURFACE TROF LEFT FROM THE WEAKENING LOW WILL LIFT NORTH OVER THE
EASTERN GULF. THIS WILL INCREASE THE WINDS OVER CLARENCE STRAIT
AND CROSS SOUND TO MIN SMALL CRAFT THIS AFTERNOON LATE TONIGHT
RESPECTIVELY. THE REST OF THE EASTERN GULF WILL REMAIN NEAR 20 KT
FROM THE ESE WITH SEAS RANGING FROM 8 TO 12 FT.

 THERE IS ABOUT AVERAGE FORECASTER CONFIDENCE FOR THE NEXT 24HRS
AND UPDATED THE FORECAST WITH A BLEND OF THE NAM/EC.

&&

.LONG TERM...MODELS ARE IN FAIR AGREEMENT WITH A WEAKENING
OCCLUDED FRONT MOVES NORTH ACROSS SOUTHEAST ALASKA FOR LIKELY TO
CATEGORICAL POPS SPREADING NORTH THROUGH LATE THURSDAY. A
DEVELOPING LOW WILL ENTER THE SOUTHEAST GULF ON THURSDAY MORNING
THEN STRENGTHEN AS IT MOVES NORTHWARD ACROSS THE EASTERN GULF
THURSDAY NIGHT THROUGH FRIDAY...THEN WEAKENS AS IT REACHES
NORTHERN GULF BY SATURDAY MORNING. A STRONG FRONTAL BOUNDARY WILL
LIKELY TO ACCOMPANY THE LOW WITH ANOTHER ROUND OF LIKELY TO
CATEGORICAL POPS SPREADING NORTH ACROSS THE PANHANDLE.

 BOUNDARY LAYER WINDS WILL BE ENHANCING UP TO 60 TO 65 KNOTS LATE
THURSDAY THROUGH EARLY SATURDAY AND EXPECT SOLID GALE FORCE WINDS
OVER THE OUTER WATERS...AS WELL AS ACROSS THE SOUTHERN INNER
CHANNELS. SOUTHWESTERN AND CENTRAL PANHANDLE COASTAL SECTIONS WILL
BECOME WINDY WITH GUSTS UP TO 40 TO 45 MPH. REFRESHED THE
INHERITED FORECAST PACKAGE WITH THE GFS THROUGH SATURDAY MORNING.

 MODEL SPREADS BECOME A LITTLE LARGER FROM LATE SATURDAY
ONWARD...AND LEANED OVER THE HPC APPROACH OF HEAVY WEIGHTING ON
THE ECMWF AND ECMWF ENSEMBLE MEANS. THE LOW OVER THE NORTHERN GULF
WILL CONTINUE TO WEAKEN AND THE PRECIPITATION ACROSS THE PANHANDLE
WILL GRADUALLY DIMINISH LATE SATURDAY INTO SUNDAY. MODEL CONSENSUS
CONTINUES HINTING A WEAK RIDGE DEVELOPS EARLY NEXT WEEK...FOLLOWED
BY ANOTHER WEAK FRONTAL BOUNDARY MOVES INTO THE PANHANDLE COASTAL
AREAS ON TUESDAY WITH LIKELY POPS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-036-041>043.

&&

ABJ/AHN