Flash Flooding and Heavy Rain in Hawaii, February 24 to 26, 2012

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HONOLULU HI
1155 PM HST THU FEB 23 2012

.UPDATE...
I HAVE UPDATED THE FORECASTS FOR THE AREA AROUND KAUAI COUNTY SINCE
AN AREA OF ENHANCED SHOWERS WILL BE MOVING OVER NIIHAU AND KAUAI
FROM THE SOUTHEAST OVER THE NEXT FEW HOURS.

&&

.SYNOPSIS...
SURFACE HIGH PRESSURE WILL KEEP TRADE WINDS BLOWING OVER THE ISLANDS
THROUGH NEXT WEEK. A LOW ALOFT EAST SOUTHEAST OF THE BIG ISLAND WILL
MOVE NORTH AND WEAKEN BRINGING MORE STABLE WEATHER TO THE EASTERN
ISLANDS. HOWEVER...A NEW LOW ALOFT WILL FORM WEST OF KAUAI. THAT
LOW WILL SHIFT THE WINDS OUT OF THE SOUTHEAST NEAR KAUAI AND
INCREASE THE CHANCE OF LOCALLY HEAVY SHOWERS ON KAUAI AND OAHU OVER
THE WEEKEND. MORE STABLE WEATHER WILL RETURN NEXT WEEK AS THE LOW
ALOFT WEAKENS AND MOVES AWAY TO THE NORTHWEST.

&&

.DISCUSSION...
A LOW ALOFT ABOUT 300 MILES EAST OF THE BIG ISLAND WILL MOVE
NORTHEAST AND WEAKEN. AS THE LOW MOVES AWAY...THE ATMOSPHERE NEAR
THE BIG ISLAND WILL STABILIZE. MEANWHILE...A TROUGH ALOFT IS DIGGING
TOWARD THE ISLANDS FROM THE NORTHWEST AND WILL CUT OFF A NEW LOW
ALOFT. THE GLOBAL MODELS HAVE COME INTO BETTER AGREEMENT ON THE
LOW. THIS SYSTEM HAS INDUCED A SURFACE TROUGH WEST OF KAUAI SO THE
LOW LEVEL WINDS NEAR KAUAI ARE SHIFTING OUT OF THE EAST SOUTHEAST.
THE LOW ALOFT WILL ALSO MAKE THE ATMOSPHERE SOMEWHAT UNSTABLE NEAR
KAUAI AND OAHU OVER THE NEXT FEW DAYS.

EASTERLY TRADE WINDS WILL CONTINUE NEAR THE BIG ISLAND BUT THE LOW
LEVEL FLOW NEAR KAUAI WILL REMAIN OUT OF THE EAST SOUTHEAST THROUGH
MUCH OF NEXT WEEK. OVER THE NEXT FEW DAYS...INSTABILITY FROM THE LOW
ALOFT AND LEE PLUMES IN THE EAST SOUTHEAST LOW LEVEL FLOW WILL
PRODUCE A THREAT OF LOCALLY HEAVY SHOWERS OVER KAUAI COUNTY AND
POSSIBLY OAHU.

THE LOW ALOFT WILL MOVE NORTHWEST AND WEAKEN EARLY NEXT WEEK AND THE
ATMOSPHERE AROUND THE MAIN HAWAIIAN ISLANDS WILL STABILIZE. SURFACE
HIGH PRESSURE WILL KEEP TRADE WINDS BLOWING OVER THE ISLANDS BUT A
PERSISTENT SURFACE TROUGH WEST OF KAUAI WILL KEEP THE WINDS OUT OF
THE EAST SOUTHEAST NEAR KAUAI THROUGH THE MIDDLE OF NEXT WEEK.
RECENT RUNS OF THE GFS SUGGEST THAT A NEW STRONG LOW MAY BRING
STRONG EAST NORTHEAST TRADE WINDS BY THE END OF NEXT WEEK...BUT THAT
REMAINS UNCERTAIN.

&&

.MARINE...
A SMALL CRAFT ADVISORY CONTINUES FOR THE TYPICALLY WINDY WATERS
AROUND MAUI AND THE BIG ISLAND. WE MAY BE ABLE TO DROP THE ADVISORY
BY 400 AM.

HAZARDOUS SEAS DUE TO AN EAST SWELL WILL DECREASE OVERNIGHT. WE
EXPECT TO DROP THE HIGH SURF ADVISORY FOR EAST FACING SHORES BY 400
AM. A NEW NORTHWEST SWELL ARRIVING SATURDAY WILL BE FAIRLY LARGE...
BUT SURF FROM THAT SWELL WILL PROBABLY PEAK BELOW THE ADVISORY LEVEL
ON SUNDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY THROUGH 400 AM FRIDAY FOR EAST FACING SHORES OF
KAUAI OAHU MOLOKAI MAUI AND THE BIG ISLAND.

SMALL CRAFT ADVISORY THROUGH 400 AM FRIDAY FOR THE PAILOLO AND
ALENUIHAHA CHANNELS AND WATERS SOUTH AND WEST OF THE BIG ISLAND.

&&

DONALDSON