Flash Flood Warning 130, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE SEP 26 2006

.SYNOPSIS...
TRADE WINDS WILL RULE THE HAWAIIAN ISLANDS THROUGH THE REST OF THE
WEEK. THE CURRENT LIGHT TRADES WILL PICK UP A NOTCH TODAY AND
PERSIST INTO THE WEEKEND. A WEAK TROUGH OF LOW PRESSURE AT THE MID
AND UPPER LEVELS OF THE ATMOSPHERE WILL ENHANCE SOME OF THE SHOWERS
ACROSS THE STATE FOR THE NEXT COUPLE OF DAYS.

&&
.DISCUSSION...
QUITE A BIT OF ACTIVITY DURING THE EVENING HOURS WITH LOCALLY HEAVY
SHOWERS AND OR ISOLATED THUNDERSTORMS REPORTED ON ALL BUT
MOLOKAI...LANAI AND MAUI. THE HILO AREA HAD SPORADIC HEAVY SHOWERS
AND A COUPLE OF THUNDERSTORMS. THE PAHALA AREA DOWN THE KAU DISTRICT
HAD HEAVY RAINS AS WELL WARRANTING A FLASH FLOOD WARNING. IT HAS
SINCE BEEN CANCELLED. ALTHOUGH THERE WEREN/T ANY RAIN GAGE ALARMS
THAT SOUNDED OFF ON MAUI...RADAR SHOWED OCCASIONAL SHOWERS IN THE
AREA ABOVE HANA. ON THE OTHER ISLANDS...OCCASIONAL SHOWERS WERE
CONFINED TO MAINLY THE WINDWARD AND MOUNTAIN AREAS. A FLOOD ADVISORY
WAS ISSUED FOR THE KOOLAU/S AND WINDWARD COMMUNITIES ON OAHU A FEW
HOURS AGO.

THE CULPRIT OF THIS UNSTABLE TRADE WIND PATTERN IS A DEEPENING
TROUGH OVER THE ISLANDS. ALTHOUGH THE MOISTURE IS MARGINAL AND THE
DEPTH SHALLOW...AMPLE DYNAMICS ARE PRESENT ESPECIALLY FOR TODAY.

WE ARE LEANING TOWARDS A FLOOD WATCH FOR TODAY STATEWIDE. THE TRADES
ARE CURRENTLY LIGHT TO MODERATE...AND WE SHOULD GET SOME
STRENGTHENING LATER TODAY NOW THAT THE 24 HOUR PRESSURE DIFFERENCE
IS SHOWING SIGNS OF TURNING POSITIVE. BUT BELIEVE THE TRADES WILL
STAY LIGHT LONG ENOUGH FOR SOME LOCAL SEA BREEZES...HENCE SOME
INTERIOR CLOUDINESS BY LATE MORNING OR EARLY AFTERNOON. WITH THE
ADDITION OF FAVORABLE DYNAMICS...THE HEAVY SHOWERS MAY NOT ONLY BE
CONFINED TO THE WINDWARD AND MOUNTAIN AREAS BUT OVER THE INTERIOR
SECTIONS AS WELL.

THE DYNAMICS ARE NOT FAVOR AFTER TODAY SO WILL LIKELY SEE FEWER
ENHANCED SHOWERS AFTER TODAY. THE MORE TYPICAL TRADE WIND REGIME
SHOULD RETURN BY FRIDAY AS THE TROUGH DEPARTS THE ISLAND SCENE.
AS FOR THE WEEKEND FORECAST...SOME OF THE MODELS SUGGEST ANOTHER LOW
NORTHWEST OF KAUAI. WILL BE OPTIMISTIC FOR NOW A STAY WITH A STABLE
TRADE WIND REGIME.

&&

.MARINE...
THE REMNANTS OF FORMER HURRICANE YAGI IS EXPECTED TO STRENGTHEN TO
HURRICANE FORCE IN THE NEXT 12 HOURS AS IT PASSES WELL NORTH OF THE
HAWAIIAN ISLANDS. WAVE MODEL SUGGEST A SWELL FROM YAGI TO REACH THE
HAWAIIAN ISLANDS FRIDAY WITH SURF HEIGHTS NEAR ADVISORY LEVELS FOR
THE NORTH AND WEST FACING SHORES.

.HFO WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH ALL ISLANDS UNTIL 11
PM HST TUESDAY NIGHT.

&&

LAU