Heavy Rain in Hawaii, March 14 to 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST WED MAR 14 2007

.SYNOPSIS...CLOUDY SKIES AND HUMID CONDITIONS WILL CONTINUE OVER THE
ISLANDS AS A COLD FRONT NEAR KAUAI MOVES SLOWLY EAST. THE FRONT
CONTINUES TO BRING A THREAT OF HEAVY SHOWERS TO THE ISLANDS...BUT
THEY ARE NOT EXPECTED TO REMAIN OVER ANY ONE LOCATION FOR AN
EXTENDED TIME PERIOD...AND THE FLASH FLOOD WATCH HAS BEEN CANCELLED.
THE FRONT WILL MOVE OVER MAUI COUNTY BY TONIGHT...AND THE BIG ISLAND
BY FRIDAY...BUT IT WILL BE WEAKENING...WITH DECREASING CHANCES FOR
HEAVY RAIN. THE FRONT WILL DISSIPATE NEAR THE BIG ISLAND ON
FRIDAY...AND THE WEEKEND WILL HAVE MODERATE TRADE WINDS AND MORE
SETTLED WEATHER.

&&

.DISCUSSION...THE ISLANDS CONTINUE TO BE COVERED BY AN OVERCAST DECK
OF MULTI-LAYERED CLOUDS THIS MORNING...WHICH...IN CONJUNCTION WITH A
MOIST SOUTHERLY WIND FLOW...HAS KEPT OVERNIGHT TEMPERATURES IN MOST
AREAS FROM FALLING OUT OF THE 70/S. RADAR SHOWS HEAVY RAIN AROUND
KAUAI...AND OVER WATERS SOUTH AND WEST OF KAUAI AND OAHU. A COLD
FRONT CONTINUES TO LINGER NEAR KAUAI...AND MOIST SOUTHERLY FLOW
AHEAD OF THE FRONT IS CONTRIBUTING TO THE MOIST AND UNSETTLED AIR
MASS OVER THE ISLANDS. IN THE MID AND UPPER LEVELS...THE FLOW IS
SOUTHWESTERLY...AS THE ISLANDS LIE TO THE EAST OF A BROAD UPPER
TROUGH.

THE ANTICIPATED SHORT WAVE TROUGH ALOFT...CURRENTLY SEEN ON WATER
VAPOR IMAGERY ABOUT 150 MILES WEST OF KAUAI NEAR 22N 162W...IS
MOVING RAPIDLY EAST NEAR 40 MPH. CLOUD TOPS HAVE BEEN COOLING OVER
THE PAST FEW HOURS IN ADVANCE OF THIS TROUGH...NAMELY OVER WATER
SOUTHWEST OF KAUAI AND OAHU...AND TO A GREATER EXTENT OVER WATER
NORTHEAST OF KAUAI. THE 230 AM SATELLITE INTERPRETATION MESSAGE CAN
BE FOUND UNDER PRODUCT HEADER SIMHI...AND CONTAINS A DETAILED
DESCRIPTION OF THE CLOUDS SEEN AROUND THE ISLANDS THIS MORNING.
THE SHORT WAVE WILL LIKELY CONTINUE TO DRIVE DEEP CONVECTION THROUGH
THE EARLY MORNING HOURS...BUT SHOWERS ARE MOVING ALONG SMARTLY AND
ARE NOT EXPECTED TO LINGER OVER ANY ONE AREA FOR AN EXTENDED PERIOD
OF TIME. IN ADDITION...THE SHORT WAVE WILL BE EAST OF THE ISLANDS BY
MID-MORNING AND UPPER SUPPORT FOR WIDESPREAD HEAVY RAIN ALONG THE
WEAK FRONTAL BOUNDARY WILL BE DIMINISHING. THEREFORE THE FLASH
FLOOD WATCH HAS BEEN CANCELLED.

THE UPPER TROUGH IS BRINGING A DEEP LAYER OF MOISTURE AND HIGH
HUMIDITIES TO THE SUMMITS ON THE BIG ISLAND...AND A WINTRY MIX OF
WEATHER IS EXPECTED AS TEMPERATURES WILL DIP BELOW FREEZING
OVERNIGHT...OR IN CONVECTIVE CLOUDS DURING THE DAY. CONDITIONS
THERE WILL BE MONITORED IN CASE A WIND AND/OR WINTER WEATHER
ADVISORY IS NECESSARY.

THE FRONT IS EXPECTED TO MOVE EAST OF KAUAI BY THIS AFTERNOON...
TO BE EAST OF OAHU BY THIS EVENING...DRIVEN EASTWARD BY THE SHORT
WAVE NOW PUSHING EAST ACROSS THE ISLANDS. THE FRONT WILL WEAKEN TO A
SHEAR LINE AS IT MOVES OVER BIG ISLAND LATE THURSDAY AND FRIDAY.
THE BOUNDARY WILL DISSIPATE SLOWLY AS IT BRINGS CLOUDS AND SHOWERS
TO WINDWARD BIG ISLAND ON FRIDAY AND SATURDAY...AS A LIGHT
NORTHEAST FLOW FILLS IN NORTH OF THIS BOUNDARY. HIGH PRESSURE
BUILDING NORTH OF THE ISLANDS...WORKING IN CONJUNCTION WITH A
MID-LEVEL RIDGE OVER THE ISLANDS...WILL BRING A MORE SETTLED WEATHER
PATTERN...WITH MODERATE TO FRESH TRADE WINDS FOR THE WEEKEND INTO
NEXT WEEK.

&&

.MARINE...
A HIGH SURF WARNING REMAINS IN EFFECT FOR A LARGE NORTHWEST SWELL
RESULTING IN DANGEROUSLY HIGH SURF ALONG NORTH AND WEST FACING
SHORES...BUT THE TREND WILL BE DOWN FOR KAUAI AND OAHU TODAY...WHILE
IT MAY TAKE UNTIL LATER THIS MORNING FOR THE SWELL TO PEAK ON MAUI
AND THE BIG ISLAND. SEE SRFHFO AND CFWHFO AND CWFHFO FOR MORE ON
THIS EVENT.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 4 PM HST TODAY FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI AND OAHU.

HIGH SURF WARNING UNTIL 4 AM HST THURSDAY FOR NORTH FACING SHORES
OF MAUI AND WEST FACING SHORES OF THE BIG ISLAND.

SMALL CRAFT ADVISORY DUE TO LARGE OPEN OCEAN SWELL UNTIL 6 PM HST
THURSDAY FOR ALL WATERS EXCEPT MAALAEA BAY AND PAILOLO CHANNEL.

&&

BIRCHARD