Flash Flood Warning 138, NWS Honolulu, HI

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
710 PM HST MON OCT 16 2006

.SYNOPSIS... A COLD FRONT OVER MAUI WILL PUSH SLOWLY EAST TO THE BIG
ISLAND TONIGHT AND TUESDAY. THE FRONT WILL PUSH EAST OF THE STATE
LATER ON TUESDAY. A SECOND COLD FRONT WILL REACH KAUAI TONIGHT AND
MOVE TO NEAR OAHU ON TUESDAY. WINDS ARE EXPECTED TO REMAIN RATHER
LIGHT FOR THE LATTER HALF OF THE WEAK AS A WEAK SURFACE TROUGH
REMAINS NEAR THE ISLANDS.

&&

.UPDATE...AT 645 PM...RADAR AT SATELLITE INDICATES A LINE OF HEAVY
SHOWERS AND POSSIBLE SEVERE THUNDERSTORMS APPROACHING THE KONA COAST
OF THE BIG ISLAND. A SEVERE THUNDERSTOM WATCH WAS THEREFORE ISSUED
FOR THE ENTIRE BIG ISLAND THROUGH 1 AM HST TUESDAY. IN ADDITION TO
THE LINE OF HEAVY SHOWERS AND THUNDERSTORMS APPROACHING THE KONA
COAST...ISOLATED HEAVY SHOWERS AND THUNDERSTORMS CONTINUE TO FALL
OVER THE SOUTHEAST AND WINDARD SIDES OF THE BIG ISLAND. A FLOOD
ADVISORY HAS ADDITIONALLY BEEN ISSUED THROUGH 9 PM HST AND MAY NEED
TO BE UPGRADED TO WARNING LATER THIS EVENING.

.PREV DISCUSSION ... THE COLD FRONT OVER MAUI HAS SLOWED TO A CRAWL
AND CONTINUES TO BE THE FOCUS FOR SHOWERS AND ISOLATED
THUNDERSTORMS. LOW AND MID LEVEL MOISTURE...SOME OF THE REMNANTS
FROM TD 04C...IS BEING DRAWN NORTHWARD ALONG THIS FRONT. IN
ADDITION...AN IMPRESSIVE UPPER LEVEL LOW CONTINUES TO DIG SOUTHWARD
NEAR 26N 162W...ALSO HELPING TO REENERGIZE THIS FRONT...AND IN
FACT...HAS CREATED A SECONDARY COLD FRONT NW OF KAUAI.

THE MID-LEVELS ARE COLD ENOUGH OVER THE SECONDARY FRONT NEAR KAUAI
TO ALLOW SOME ISOLATED THUNDERSTORMS TO DEVELOP OVERNIGHT. WHILE
MOST OF THESE WILL PASS NORTH OF KAUAI...WE COULD SEE A FEW
LIGHTNING FLASHES WITH THE CELLS NEAR KAUAI. IN CONTRAST...THE
LEADING BOUNDARY...THAT FRONT OVER MAUI...HAS BETTER MOISTURE TO
WORK WITH...BUT IS STILL AHEAD OF THE STRONGER INSTABILITY.
NEVERTHELESS...AS WE HAVE SEEN TODAY...THE MOST VIGOROUS CELLS COULD
PRODUCE THUNDER AND LIGHTNING TONIGHT AND TUESDAY.

THE MAIN THREAT WILL BE THE HEAVY RAIN. INCREASING DEEP LAYER
MOISTURE ALONG THIS SLOW MOVING BOUNDARY SETS THE STAGE FOR
TRAINING AND/OR ANCHORED CELLS OVER FAVORED TERRAIN. MOST
SUSCEPTIBLE ARE SOUTH AND WEST FACING SLOPES OF MAUI AND THE BIG
ISLAND...BUT THESE ARE NOT THE ONLY AREAS AT RISK. INTERESTING TO
NOTE THAT THERE IS SOME DEEP LAYER VEERING AND THE GFS MODEL
SUGGESTS THERE MAY BE ENOUGH SPEED SHEAR FOR A FEW STRONG STORMS
NEAR THE BIG ISLAND OVERNIGHT. LATER SHIFT MAY NEED TO WATCH FOR
CELLS MEETING SPECIAL MARINE WARNING CRITERIA.

IT STILL APPEARS THAT THE DEEPEST MOISTURE WILL BE PUSHED EAST OF
THE BIG ISLAND LATER ON TUESDAY. WE WILL REMAIN IN A SOMEWHAT
UNSETTLED PATTERN FOR THE REMAINDER OF THE WEEK AS THE MODELS
INDICATE ANOTHER UPPER LEVEL TROUGH DIGGING INTO THE MEAN TROUGH
POSITION JUST WEST OF THE ISLANDS...AND WEAK SURFACE TROUGHING
NEAR THE ISLANDS. THERE WILL ALSO BE QUITE A BIT OF LINGERING
MOISTURE NEAR THE ISLANDS...AS WELL...WITH THE MODELS IN
DISAGREEMENT ABOUT THE DETAILS OF HOW MUCH AND WHERE. IT IS
DIFFICULT TO SAY AT THIS POINT WHETHER WE WILL SETTLE INTO A
PATTERN OF LIGHT TRADES...OR MAINTAIN MORE OF A CONVECTIVE PATTERN
FOR THE LATTER HALF OF THE WEEK. WE WILL CONTINUE A HYBRID TYPE
PATTERN IN THE GRIDS FOR NOW...BUT REFINEMENTS WILL LIKELY BE
NEEDED LATER.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH THROUGH 1 AM TUESDAY FOR THE BIG ISLAND
AND SURROUNDING COASTAL WATERS.
FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR MOLOKAI-LANAI-
KAHOOLAWE-MAUI-BIG ISLAND.

&&

TANABE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
247 PM HST MON OCT 16 2006

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

1258 PM     FLASH FLOOD      2 N KIHEI               20.79N 156.45W
10/16/2006                   MAUI IN MAUI       HI   EMERGENCY MNGR

            JUNCTION OF PIILANI AND MOKULELE HIGHWAYS CLOSED DUE TO
            FLOODING AND DEBRIS ON ROAD.

&&

KODAMA