Heavy Rain in Hawaii, February 2, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE FEB 2 2010

.SYNOPSIS...
AN APPROACHING FRONT FROM THE NORTHWEST WILL BRING INCREASING CLOUDS
AND SHOWERS TO MOST OF THE ISLANDS TODAY. THIS FRONT IS EXPECTED TO
REACH THE BIG ISLAND EARLY WEDNESDAY...BRINGING A COOL AND DRIER AIR
MASS WITH FRESH NORTHERLY WINDS BEHIND. MORE TYPICAL...THOUGH
DRIER...TRADE WINDS WILL RETURN THURSDAY. THE TRADES MAY BE
SHORT-LIVED AS WINDS MAY TURN LIGHT SOUTHERLY AGAIN BY THE WEEKEND
AHEAD OF POSSIBLY ANOTHER WEAK FRONT FROM THE NORTHWEST.

&&

.DISCUSSION...
PREFRONTAL CLOUDS FINALLY MOVED OVER KAUAI OVERNIGHT...THOUGH MOST
OF THE RAIN HAS YET TO REACH THE GARDEN ISLE THIS MORNING. LATEST
RADAR DATA INDICATE A LINE OF SHOWERS OVER NIIHAU EARLY THIS
MORNING...AND THIS LINE OF SHOWERS WILL REACH KAUAI IN THE NEXT HOUR
OR SO. ELSEWHERE MORE CLOUDS HAVE DEVELOPED OVERNIGHT...WITH ANOTHER
RAIN BAND FORMED JUST SOUTHWEST OF MAUI COUNTY EARLY THIS MORNING.
THIS BAND IS ALSO ADVANCING SLOWLY NORTHEAST...AND SHOULD AFFECT
MAUI COUNTY IN THE NEXT FEW HOURS UNDER THE SOUTHWESTERLY FLOW.
THERE IS ALSO AN AREA OF RAIN CLOUDS A LITTLE WAYS SOUTHWEST OF
OAHU...AND WILL PROBABLY REACH THE ISLAND LATER THIS MORNING. THE
LEADING EDGE OF THE FRONT IS STILL ABOUT 200 MILES NORTHWEST OF
KAUAI AND THE FRONT IS ADVANCING SOUTHEAST AT ABOUT 15 MILES PER
HOUR. THIS FRONT APPEARS TO BE WEAKENING AS IT PUSHES SOUTH...SINCE
MOST DYNAMICS ASSOCIATED WITH THIS FRONT WILL REMAIN NORTH OF THE
AREA. HENCE STILL EXPECT THE ISLANDS WILL SEE MOST PRECIPITATION
FROM THE PREFRONTAL CLOUDS TODAY...WHILE THE PASSAGE OF THE FRONT
WILL BRING IN SOME AS WELL. STILL BELIEVE FLOODING WILL NOT BE A BIG
PROBLEM WITH THIS EVENT AS THE RAIN BANDS ARE MOVING
STEADILY...THOUGH LOCALIZED HEAVIER SHOWERS COULD CAUSE PROBLEMS TO
LOW LYING OR POOR DRAINAGE AREAS. HOPEFULLY THERE WILL BE ENOUGH
PRECIPITATION TO HELP THE DROUGHT AREAS TEMPORARILY. AN UPPER LEVEL
TROUGH ASSOCIATED WITH THE FRONT WILL MOVE THROUGH THE ISLANDS
TODAY THROUGH WEDNESDAY ALSO...AND MAY BRING ADVISORY LEVEL WINDS
FOR THE SUMMITS. HAVE TO MONITOR THIS DEVELOPING WEATHER SITUATION.
THIS FRONT IS EXPECTED TO PUSH THROUGH THE ISLANDS TODAY AND
TONIGHT...REACHING THE BIG ISLAND EARLY WEDNESDAY THEN DISSIPATING.
A COOLER AND DRIER FRESH NORTHERLY WINDS WILL MOVE OVER THE ISLANDS
BEHIND THE FRONT. THUS EXPECT GOOD CLEARING BEHIND THE FRONT FOR THE
NORTHERN ISLANDS LATER TODAY...THEN SPREADING TO THE REST OF THE
ISLANDS ON WEDNESDAY.

A SURFACE HIGH PRESSURE WILL PASS NORTH OF THE ISLANDS THURSDAY
THROUGH EARLY FRIDAY...BRINGING LIGHT TO MODERATE TRADE WINDS TO THE
ISLANDS. FORECAST CHARTS INDICATE AIR MASS WILL REMAIN STABLE AND
DRY IN THE ISLAND VICINITY. THIS DRIER TRADE WIND WEATHER
UNFORTUNATELY WILL LAST A DAY OR TWO AT MOST...AS LATEST FORECAST
CHARTS CONTINUE TO INDICATE A SURFACE RIDGE WILL SAG NEAR THE
ISLANDS BY THE WEEKEND. THIS NEXT SYSTEM MAY BE SO WEAK THAT IT WILL
HAVE LITTLE IMPACT ON THE ISLAND WEATHER...SANS THE WINDS. EASTERLY
TRADES MAY RETURN EARLY NEXT WEEK FOR A DAY OR SO...ACCORDING TO THE
FORECAST CHARTS...THOUGH ANOTHER WEAK SYSTEM MAY BRUSH BY THE
NORTHERN PORTION OF THE ISLAND CHAIN EARLY NEXT WEEK...WITH WINDS
BECOMING LIGHT AGAIN. THE TIMING OF THESE SYSTEMS ARE
QUESTIONABLE...AS THE MODEL SOLUTIONS DIVERGE IN THE EXTENDED PERIOD.

&&

.MARINE...
THE NEXT NORTHWEST SWELL IS STILL EXPECTED TO REACH THE NORTHERN
ISLANDS THIS AFTERNOON...PEAKING ON WEDNESDAY/WEDNESDAY NIGHT WITH
SURF ABOVE ADVISORY LEVELS ON MANY NORTH AND WEST FACING
SHORES...THEN SLOWLY DECLINING THROUGH FRIDAY. HAVE ISSUED HIGH SURF
ADVISORY FOR NORTH AND WEST FACING SHORES MOST NORTHERN ISLANDS
EFFECTIVE THIS AFTERNOON. INCREASING NORTHERLY WINDS...COMBINED WITH
THE BUILDING NORTHWEST SWELL...WILL BRING SMALL CRAFT ADVISORY
CONDITIONS TO MANY MARINE ZONES THIS EVENING THROUGH AT LEAST
WEDNESDAY.

&&

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

&&

HUI