Flash Flood Warning 4, NWS Honolulu, HI

652 
WGHW70 PHFO 120007
FFSHFO

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE HONOLULU HI
207 PM HST WED FEB 11 2009

HIC003-120016-
/O.CAN.PHFO.FF.W.0004.000000T0000Z-090212T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
OAHU IN HONOLULU COUNTY-
207 PM HST WED FEB 11 2009

...THE FLASH FLOOD WARNING IS CANCELLED FOR THE ISLAND OF OAHU IN
HONOLULU COUNTY...

LAT...LON 2143 15814 2144 15790 2131 15791 2130 15811

$$
DONALDSON

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST WED FEB 11 2009

.SYNOPSIS...
A LOW ALOFT WILL MAKE THE ATMOSPHERE UNSTABLE...CREATING A CHANCE OF
HEAVY SHOWERS OR THUNDERSTORMS THROUGH TOMORROW. A SURFACE TROUGH
WILL KEEP WINDS LIGHT OVER MOST AREAS TODAY...BUT TRADE WINDS WILL
BUILD BACK OVER THE ISLANDS TOMORROW AS HIGH PRESSURE STRENGTHENS
NORTHEAST OF THE AREA. THE STRONG HIGH PRESSURE WILL BRING
SHOWERY...LOCALLY WINDY WEATHER THROUGH EARLY NEXT WEEK.

&&

.DISCUSSION...
WEATHER OVER THE ISLANDS HAS QUIETED DOWN OVER THE PAST FEW HOURS.
CLOUDS ARE QUITE SPARSE FROM OAHU TO MOLOKAI AND RADARS SHOW SHOWERS
ONLY OVER THE SOUTHEAST PARTS OF MAUI AND THE BIG ISLAND. WINDS ARE
LIGHT EXCEPT NEAR SOUTH POINT AND OVER THE SLOPES OF KAHOOLAWE WHERE
MODERATE TRADE WINDS ARE BLOWING. THE WEATHER WILL REMAIN FAIRLY
QUIET FOR THE NEXT COUPLE OF HOURS.

A TROUGH IS MAKING THE ATMOSPHERE OVER THE ISLANDS UNSTABLE. A LOW
ALOFT IS CENTERED ABOUT 425 MILES NORTH NORTHEAST OF KAUAI WITH A
TROUGH EXTENDING FROM THE LOW TO A POINT AROUND 100 MILES NORTHWEST
OF KAUAI. THE TROUGH WILL SHARPEN UP AND DIG SOUTHEAST THROUGH
THURSDAY EVENING AND THE ATMOSPHERE WILL REMAIN UNSTABLE TILL THEN.
THERE IS ALSO A TROUGH AT THE SURFACE OVER THE ISLANDS. MODERATE
TRADE WINDS ARE BLOWING SOUTH OF THE BIG ISLAND BUT THE SURFACE
TROUGH IS MAKING THE WINDS LIGHT FROM MAUI TO KAUAI. WITH THE
UNSTABLE ATMOSPHERE AND LIGHT WINDS...CLOUDS WILL BUILD UP OVER THE
ISLANDS THIS AFTERNOON AND CONVECTIVE CLOUD BUILDUPS WILL PRODUCE
HEAVY SHOWERS AND THUNDERSTORMS. THE HEAVY SHOWERS AND THUNDERSTORMS
WILL SHIFT OFFSHORE TONIGHT. THE ATMOSPHERE WILL BE UNSTABLE AGAIN
TOMORROW...SO MORE HEAVY SHOWERS AND THUNDERSTORMS ARE POSSIBLE.
HOWEVER...TRADE WINDS WILL BE BUILDING BACK OVER THE ISLANDS
TOMORROW...SO THE CONVECTION WILL BE MORE LIMITED.

A LOW ALOFT WILL CUT OFF JUST SOUTH OF THE ISLANDS TOMORROW NIGHT.
THE LOW WILL MOVE WEST AS A STRONG RIDGE ALOFT BUILDS NORTH OF THE
ISLANDS OVER THE WEEKEND. AS THE LOW ALOFT MOVES WEST AND THE RIDGE
ALOFT BUILDS TO THE NORTH THE ATMOSPHERE WILL BECOME MORE STABLE AND
STRONG TRADE WINDS WILL BUILD OVER THE ISLANDS. THE TRADE WINDS MAY
GET STRONG ENOUGH TO REQUIRE WIND ADVISORIES AND EVEN HIGH WIND
WARNINGS ARE POSSIBLE...ESPECIALLY FOR HALEAKALA SUMMIT. THE
ATMOSPHERE WILL GET STABLE ENOUGH THURSDAY NIGHT TO END THE THREAT
OF DEEP CONVECTION...BUT THE LOWER ATMOSPHERE WILL REMAIN MOIST. THE
TRADE WINDS WILL CARRY SHOWERY LOW CLOUDS ACROSS WINDWARD AREAS AND
SPREAD SOME OF THE SHOWERS OVER LEEWARD AREAS OF THE SMALLER ISLANDS.

TRADE WINDS WILL PEAK OVER THE WEEKEND...BUT THE MODELS SHOW SURFACE
PRESSURES NORTH OF THE ISLANDS REMAINING UNUSUALLY HIGH THROUGH THE
MIDDLE OF NEXT WEEK. LOCALLY BREEZY TRADE WINDS ARE LIKELY TO
CONTINUE THROUGH AT LEAST NEXT THURSDAY.

&&

.MARINE...
THE NORTHWEST SWELL AT BUOY 51001...NORTHWEST OF KAUAI...INCREASED
OVERNIGHT AND WILL BE PRODUCING HIGH SURF ALONG NORTHWEST FACING
SHORES FROM NIIHAU TO MAUI TODAY. THE SURF ALONG THE NORTHWEST
FACING SHORES WILL DROP BELOW THE ADVISORY THRESHOLD TONIGHT.

TRADE WINDS WILL BE GETTING QUITE STRONG OVER THE NEXT 36 HOURS. THE
WINDS WILL REACH NEAR GALE FORCE AND SMALL CRAFT ADVISORIES ARE
LIKELY FOR ALL THE COASTAL ZONES. THERE IS EVEN A POSSIBILITY THAT
GALE WARNINGS MAY BE REQUIRED FOR THE WINDIEST ZONES. THE TRADE
WINDS WILL ALSO PRODUCE VERY ROUGH SEAS. THE WAVES MAY REQUIRE HIGH
SURF ADVISORIES FOR EAST FACING SHORES. WIND SPEEDS WILL PEAK OVER
THE WEEKEND BUT TRADE WINDS WILL REMAIN STRONGER THAN USUAL WELL
INTO NEXT WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES OF NIIHAU AND
KAUAI AND NORTH FACING SHORES OF OAHU MOLOKAI AND MAUI.

WINTER WEATHER ADVISORY FOR BIG ISLAND SUMMITS FROM NOON UNTIL 6 PM
TODAY.

&&

DONALDSON