Heavy Rain in Hawaii, March 13, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1020 AM HST TUE MAR 13 2007

.SYNOPSIS...SHOWERS INCREASING AHEAD OF AN APPROACHING FRONT. THE
FRONT BRINGS THE THREAT OF LOCALLY HEAVY RAIN TO KAUAI AND
OAHU...AND MODERATE RAIN TO MAUI COUNTY THROUGH TONIGHT. THE FRONT
WILL MOVE OVER MAUI COUNTY ON WEDNESDAY...AND THE BIG ISLAND BY
THURSDAY...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...AN APPROACHING COLD FRONT IS LOCATED JUST NORTHWEST
OF KAUAI. PREFRONTAL CONVERGENCE IS EVIDENT IN THE RADAR WITH AN
UNORGANIZED AREA OF LIGHT TO MODERATE PRECIPITATION SHOWING UP SOUTH
OF KAUAI... OAHU AND MOLOKAI. RAINFALL TOTALS THIS MORNING OVER
THE ISLANDS HAS BEEN SPARSE WITH HIGHEST TOTALS ON OAHU WITH 6
HOUR TOTALS OF 0.17 INCH IN WAIPIO AND 0.14 INCH IN WAIAWA. EXPECT
RAINS TO INCREASE THIS MORNING FROM KAUAI TO MAUI COUNTY.

CURRENTLY KAUAI IS DRY AND SKIES ARE CLEARING TO THE IMMEDIATE
WEST OF THE ISLAND. HOWEVER...100 MILES WEST OF KAUAI IS A LINE OF
THUNDERSTORMS MOVING 10 MPH TO THE EAST...AND WITH CLEARER SKIES
COMES WARMER SURFACE TEMPERATURES WHICH WILL INCREASE THE CHANCES
FOR CONVECTIVE ACTIVITY AND THUNDERSTORMS. SO...EVEN WITH CLEARING
SKIES NEAR KAUAI THE FLOOD WATCH WILL REMAIN THROUGH THE DAY.

OAHU...MOLOKAI AND LANAI HAVE ALL THE RAIN ACTIVITY AT THE
MOMENT...ALBEIT LIGHT TO MODERATE AMOUNTS FROM RADAR ESTIMATES.
WILL KEEP MAUI COUNTY OUT OF THE FLOOD WATCH THIS MORNING WITH
ONLY LIMITED RAINFALL SO FAR... AND MOST OF THE MODEL PRECIP IS
LOCATED OVER KAUAI AND OAHU.

ALONG WITH THE POTENTIAL FOR RAIN...THERE IS ALSO A CONCERN WITH
WINDS. SOUTHWEST WINDS AHEAD OF THE FRONT HAVE INCREASED THIS
MORNING WITH WINDS BEING ENHANCED BY THE TERRAIN. MAKUA RIDGE HAS
REPORTED SPORADIC GUSTS OVER 50 MPH WHILE DILLINGHAM HAS SEEN
GUSTS UP TO 30 MPH. SOUTHWEST WINDS WILL CONTINUE TO FUNNEL
THROUGH VALLEYS AND ACCELERATE OVER MOUNTAIN RANGES ON KAUAI AND
OAHU THROUGH THE AFTERNOON. WINDS WILL BE CAREFULLY MONITORED AND
A WIND ADVISORY WILL BE ISSUED IF NECESSARY.

THE FRONT IS EXPECTED TO MOVE TO NEAR OAHU THIS EVENING...MOVING
OVER MAUI COUNTY ON WEDNESDAY. BY THURSDAY...THE FRONT IS EXPECTED
TO BE IN THE BIG ISLAND VICINITY AND WILL HAVE WEAKENED CONSIDERABLY.

BY FRIDAY THE FRONT WILL HAVE WEAKENED TO A SHEAR LINE AND LINGERS NEAR
THE BIG ISLAND. DRIER NORTHERLY FLOW WILL BE MOVING IN BEHIND THE
FRONT...AS HIGH PRESSURE BUILDS NORTHWEST AND NORTH OF THE ISLANDS.
SATURDAY AND SUNDAY WILL SEE NORTHEASTERLY TRADES...BECOMING EASTERLY
BY MONDAY.

&&

.MARINE...
A HIGH SURF WARNING IS IN EFFECT THIS AFTERNOON IN ANTICIPATION
OF LARGE SWELLS ARRIVING FROM THE WEST-NORTHWEST THIS AFTERNOON
AND TONIGHT. BUOY 51001 HAS CLIMBED DRAMATICALLY THIS MORNING TO
17 SECONDS 22 FEET WITH A LARGE PUSH OF LONG PERIOD ENERGY. A
SMALL CRAFT ADVISORY IS IN EFFECT OVER KAUAI AND OAHU WATERS AND
WILL BE EXPANDED INTO MAUI WATERS AND THEN FINALLY BIG ISLAND
WATERS LATER TONIGHT.

GFS-BASED WAVEWATCH MODEL OUTPUT CONTINUES TO BE DISREGARDED DUE TO
BAD DATA INTRODUCED SUNDAY MORNING...AND SHOULD NOT BE USED TO
FORECAST SWELL HEIGHTS WITH THIS EVENT. THE NOGAPS-BASED WAVE WATCH
III FORECAST APPEARS TO OFFER A MORE REALISTIC SOLUTION FOR EXPECTED
SWELL HEIGHTS IN OUR WATERS. SEE SRFHFO...CWFHFO AND CFWHFO FOR
DETAILS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR OAHU.

FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR NIIHAU-KAUAI.

HIGH SURF WARNING FROM 2 PM THIS AFTERNOON TO 4 PM HST WEDNESDAY
FOR NIIHAU-KAUAI WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH
SHORE-OAHU KOOLAU-OLOMANA-MOLOKAI.

HIGH SURF WARNING FROM 10 PM THIS EVENING TO 4 AM HST THURSDAY
FOR MAUI WINDWARD WEST-WINDWARD HALEAKALA-KONA-KOHALA.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST THURSDAY
FOR ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS-BIG ISLAND
LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM HST
THURSDAY FOR KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-MAUI
COUNTY LEEWARD WATERS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST THURSDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS.

&&

MORRISON