Small Craft Advisory 405, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
355 PM AKDT TUE JUL 10 2012

.SHORT TERM...LOW PRESSURE OVER THE YUKON WILL CONTINUE TO MOVE
NE AWAY FROM THE AREA THROUGH TONIGHT. A HIGH PRESSURE RIDGE WILL
CONTINUE TO BUILD OVER THE ERN GULF AND SE AK THROUGH
TONIGHT...THEN REMAIN THERE WED. OCCLUDED FRONT WILL MOVE INTO
THE SW GULF BY LATE WED. MADE NO CHANGE TO PRESSURE FIELDS AS THE
LATEST MODELS AGREED WITH THEM.

 MAIN FORECAST CONCERNS WILL BE WINDS AND PRECIP POTENTIAL. RIGHT
NOW STRONGEST WINDS ARE OVER THE NRN INNER CHANNELS...WITH NEAR
GALE FORCE WINDS REPORTED OVER NRN LYNN CANAL AND GUSTS OF 35+ KT
AT PAGY. THESE WINDS ARE BEING DRIVEN BY A STG SLY PRES GRADIENT
ENHANCED BY STG SWLY MID-LEVEL FLOW. THE MID-LEVEL FLOW SHOULD
WEAKEN SLOWLY TONIGHT AND ALSO VEER TO A MORE WLY DIRECTION. THIS
WILL HELP WEAKEN THE SLY PRES GRADIENT TONIGHT...AND ALLOW WINDS
TO SLOWLY DECREASE. STILL...WINDS OVER THE NRN LYNN CANAL AREA
SHOULD REMAIN AOA 20KT THRU WED. WINDS OVER THE REMAINDER OF THE
AREA SHOULD BE 20 KT OR LESS...ALTHOUGH THE EXTREME WRN PART OF
THE OFFSHORE WATERS MAY SEE SCA LEVEL WINDS DEVELOP LATE WED WELL
AHEAD OF AN APPROACHING OCCLUDED FRONT.

 AS FOR PRECIP...IT HAS BECOME SHOWERY ACROSS THE AREA AND SHOULD
REMAIN SO THRU WED...EXCEPT OVER THE WRN PARTS OF THE GULF MARINE
AREAS WHERE SOME STRATIFORM PRECIP SHOULD MOVE IN AHEAD OF THE
OCCLUDED FRONT. AS FOR SHOWER COVERAGE...THE MOST WILL BE AROUND
PAYA WHERE DEEPEST UNSTABLE AIRMASS WILL BE. DEPTH OF UNSTABLE
LAYER DECREASES AS YOU GO SE...WITH THE LAYER FAIRLY SHALLOW OVER
THE SRN AREA. HOWEVER AM EXPECTING THE DEPTH OF THE UNSTABLE
LAYER TO SLOWLY DECREASE AS SHORTWAVE RIDGING BUILDS IN LATER
TONIGHT AND WED...SO POPS WILL SLOWLY DROP THRU THE PERIOD OVER
THE PANHANDLE. WENT WITH LIKELY POPS AROUND PAYA...SCT (CHANCE)
POPS OVER THE NRN AREA...AND ISOLATED (SLIGHT CHANCE) OVER THE
CENTRAL AREA TONIGHT. THIS LOWERS TO CHANCE POPS IN PAYA AND TO
SLIGHT CHANCE OVER THE NRN PANHANDLE WED...WITH POPS BELOW
20 PERCENT FURTHER S.

 OTHERWISE...WILL KEEP IN MENTION OF FOG BUT REDUCE COVERAGE TO
PATCHY FOR THE GULF AND EXTREME OUTER COAST AREA. MODELS SUGGEST
A THIN MARINE LAYER WILL DEVELOP OVER THE GULF TONIGHT...BUT AM
SKEPTICAL AS TO HOW MUCH IT WILL DEVELOP DUE TO LOW LEVEL
INSTABILITY. STILL...MAY BE ENOUGH BREAKS IN CLOUDS TO ALLOW SOME
FOG TO DEVELOP OVER THE GULF AND ALONG THE OUTER COAST.

&&

.LONG TERM...THE FORECAST THROUGH TO THE WEEKEND LOOKS LIKE IT IS
FAIRLY CLOSE TO THE PREVIOUS FORECASTS. ONLY DID SOME MINOR
ADJUSTMENTS TO THE FORECAST REGARDING THE WIND AND WEATHER ACROSS
THE AREA. USED A BLEND OF THE CURRENT WITH NAM AND GFS EARLY.. AND
BLENDED IN THE HPC SOLUTION FOR THE LATER PERIODS AS THEY INCLUDED
PORTIONS OF THE THINKING THAT WAS USED OVER THE LATER PERIODS LAST
NIGHT.

VERTICALLY STACKED LOW OVER THE BRISTOL BAY AREA WILL PERSIST AND
SLOWLY DRIFT TO THE ALASKA PENINSULA. EXPECT A WEATHER FRONT TO
SPREAD RAIN INTO THE PANHANDLE REGION LATE THURSDAY AND FRIDAY.
ALOFT WITH THE LOW NOT HEADED VERY FAR THE SOUTHWEST UPPER LEVEL
FLOW WILL STALL FOR THE WEEKEND AND EARLY PORTION OF NEXT WEEK
WEEK. THIS MEANS A CONTINUED MOIST PATTERN FOR THE NORTHEAST GULF
COAST AND NORTHERN PANHANDLE. TIMING OF THE SHORT WAVES AT THIS
TIME CAN POSE SOME FORECAST ISSUE SO HAVE JUST CHANCE LEVELS FOR
THE TIME BEING.

FORECAST CONFIDENCE IS ABOVE AVERAGE TO THE WEEKEND AND AVERAGE
AFTER THAT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ013.

&&

RWT/BEZENEK