Flash Flood Warning 51, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU MAR 9 2006

.SYNOPSIS...
THE THREAT OF HEAVY RAINFALL AND THUNDERSTORMS WILL CONTINUE THROUGH
THE DAY FRIDAY AS A SURFACE TROUGH LINGERS WEST OF KAUAI. EAST
SOUTHEAST WINDS WILL GRADUALLY BECOME EAST NORTHEAST TRADES BY
SUNDAY AS THE TROUGH MOVES AWAY...STARTING A PERIOD OF DRIER WEATHER
WHICH WILL LAST THROUGH THE REST OF THE FORECAST PERIOD.

&&

.DISCUSSION...
DEEP SOUTHEAST TO SOUTH FLOW ASSOCIATED WITH A DEEP LAYER LOW NEAR
38N 173W IS LOCKED OVER THE MAIN HAWAIIAN ISLANDS...WITH A
CONVERGENT LOW LEVEL FLOW SOUTH AND EAST OF THE LOW CENTER PRODUCING
EXTENSIVE AREAS OF RAIN...WITH EMBEDDED HEAVY SHOWERS AND
THUNDERSTORMS. AN ESPECIALLY LARGE AREA OF RAIN CONTINUES TO BE
DETECTED BY RADAR NEAR KAUAI AND OAHU...AND OVER WATERS SOUTH AND
WEST OF THESE ISLANDS. THE HEAVY SHOWERS HAVE EASED...AT LEAST FOR
NOW...OVER THE EASTERN HALF OF THE BIG ISLAND. SATELLITE IMAGERY
REVEALS SHOWERY LOW CLOUDS LOOSELY ORIENTED INTO A NORTHWEST TO
SOUTHEAST BAND OVER WATERS ABOUT 250 MILES EAST OF ALL ISLANDS...AND
THESE WILL PROVIDE ADDITIONAL MOISTURE IN THE CONVERGENT LOW LEVEL
FLOW...AND WARRANTS THE HIGH WINDWARD POPS CURRENTLY IN THE GRIDS
AND THE CONTINUATION OF THE FLASH FLOOD WATCH FOR ALL ISLANDS.

THE LOW FAR TO OUR NORTHWEST IS MOVING NORTH-NORTHEAST NEAR 30
MPH...AND PROGS CONTINUE THIS GENERAL MOVEMENT TO CONTINUE OVER THE
NEXT 24 HOURS...WITH THE LOW TO BE CENTERED OVER THE ALEUTIAN
ISLANDS BY THIS TIME TOMORROW. ONE MIGHT THINK THAT THE QUICK EXIT
OF THE LOW WOULD LEAD TO A RAPID IMPROVEMENT IN ISLAND WEATHER...BUT
PROGS ARE INSISTING THAT A LOW LEVEL TROUGH WILL DEVELOP/LINGER IN
PLACE WEST OF KAUAI THROUGH SATURDAY...BEFORE WEAKENING AND MOVING
WEST AWAY FROM THE ISLANDS. THIS SOLUTION SEEMS REASONABLE...AND IS
SHARED BY THE GLOBAL MODELS...EXCEPT GFS CONTINUES TO BE MOST
AGGRESSIVE IN DEVELOPING A WEAK SURFACE LOW JUST NORTHWEST OF
KAUAI...ALONG THE LINGERING TROUGH AXIS.

EITHER WAY THE GLOBAL MODELS AGREE THAT LOW LEVEL MOISTURE
CONVERGENCE WILL CONTINUE OVER THE ISLANDS...ESPECIALLY THE WESTERN
ISLANDS...THROUGH TOMORROW...THUS THE FLOOD WATCH HAS BEEN EXTENDED
THROUGH 6 PM FRIDAY FOR ALL ISLANDS. AS A SIDE NOTE...THE THREAT OF
FLOODING RAIN MAY DIMINISH SOONER ON THE BIG ISLAND...AND LAST
LONGER FOR KAUAI...BUT DUE TO THE UNCERTAINTY OF THE EVENT...ALL
ISLANDS ARE IN THE WATCH THROUGH FRIDAY EVENING.

HIGH PRESSURE BUILDING INTO THE NORTHEAST PACIFIC WILL ALLOW THE
TROUGH TO DRIFT WEST AWAY FROM THE ISLANDS...AND ALLOW A DRIER
MODERATE TO FRESH TRADE WIND REGIME TO BUILD IN FROM THE EAST THIS
WEEKEND. A STRONG STABILIZING RIDGE IS NOT SEEN...SO THE TRADES WILL
LIKELY BRING A FEW WINDWARD SHOWERS...BUT NOT AS INTENSE OR AS
WIDESPREAD AS CURRENTLY.

&&
MARINE...
A HIGH SURF ADVISORY IS IN EFFECT FOR EAST FACING SHORES...DUE TO
THE PRESENCE OF STRONG WINDS OFFSHORE TO THE EAST PRODUCING SEAS AND
SWELLS THAT WILL RESULT IN SURF EXCEEDING ADVISORY CRITERIA THROUGH
FRIDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH...ALL HAWAIIAN ISLANDS EXTENDED THROUGH 6 PM
FRIDAY.
SMALL CRAFT ADVISORY FOR STRONG E/SE WINDS BIG ISLAND SOUTHEAST...
BIG ISLAND WINDWARD...MAUI WINDWARD...OAHU WINDWARD...KAUAI WINDWARD
WATERS THROUGH FRIDAY AFTERNOON.
WINTER WEATHER ADVISORY...BIG ISLAND SUMMITS THROUGH 6 AM FRIDAY.

&&

BIRCHARD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
409 PM HST THU MAR 09 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0345 PM     FLASH FLOOD      1 E HANALEI             22.21N 159.49W
03/09/2006                   KAUAI IN KAUAI     HI   EMERGENCY MNGR

            KAUAI CIVIL DEFENSE REPORTED THE CLOSURE OF KUHIO HIGHWAY
            AT THE HANALEI RIVER BRIDGE DUE TO HIGH WATER LEVELS.

&&

KODAMA