Heavy Rain in Hawaii, March 9 to 10, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST SAT MAR 9 2013

.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS PORTIONS OF THE ISLAND CHAIN TONIGHT
AND SUNDAY ACCOMPANIED BY AN INCREASE IN SHOWER ACTIVITY. THE FRONT
WILL WEAKEN AND STALL OVER THE CENTRAL ISLANDS EARLY NEXT WEEK.
BREEZY SOUTH TO SOUTHWEST WINDS WILL PREVAIL OUT AHEAD OF THE FRONT
WITH LIGHT NORTHERLY WINDS FILLING IN BEHIND THE FRONT. PASSING
LIGHT SHOWERS WILL TEND TO FAVOR WINDWARD AND MAUKA AREAS NEXT WEEK.

&&

.DISCUSSION...
SATELLITE AND RADAR IMAGERY SHOWS A FRONTAL BOUNDARY LYING ACROSS
KAUAI WITH THE LEADING EDGE NOW APPROACHING OAHU FROM THE WEST. THE
FRONT HAS BEEN ACCOMPANIED BY SOME PASSING SHOWERS OVER KAUAI. ALSO
OUT AHEAD OF THE FRONT ARE SOME PASSING PRE FRONTAL SHOWERS THAT
HAVE BEEN MOVING UP OVER PORTIONS OF OAHU AND MAUI COUNTY. OVERALL
RAINFALL RATES HAVE BEEN LIGHT TO LOCALLY MODERATE. LOCALLY GUSTY
SOUTH TO SOUTHWEST WINDS WILL ALSO BE EXPERIENCED OUT AHEAD OF THE
FRONT ESPECIALLY NORTH AND EAST OF MOUNTAIN RANGES. WINDS REMAIN
RATHER STRONG OVER THE BIG ISLAND SUMMITS...THUS A WIND ADVISORY
REMAINS IN EFFECT THROUGH TONIGHT.

THE FRONT IS FORECAST TO MOVE ACROSS OAHU TONIGHT. THUS EXPECT AN
INCREASE IN SHOWERS OVER OAHU AS THE FRONTAL BAND ARRIVES. THERE
REMAINS SOME UNCERTAINTY ON HOW FAR DOWN THE ISLAND CHAIN THE FRONT
PROGRESSES. ALL THE MODELS STALL THE FRONT OUT AT SOME POINT ACROSS
THE CENTRAL PORTION OF THE STATE AS IT WEAKENS. LIGHT NORTHERLY
WINDS WILL FILL IN BEHIND THE FRONT LIKELY FORCING ANY RESIDUAL
MOISTURE INTO PASSING SHOWERS OVER NORTH AND NORTHEAST FACING
SLOPES.

THE FRONT WILL THEN WEAKEN INTO A TROUGH EARLY NEXT WEEK WITH ITS
AXIS LIKELY NEAR OR JUST NORTHEAST OF THE BIG ISLAND. WITH HIGH
PRESSURE EXPECTED TO REMAIN FAR NORTHWEST OF THE STATE...THE ISLANDS
WILL REMAIN IN A LIGHT NORTH TO NORTHEAST WIND FLOW THROUGH THE
MIDDLE OF NEXT WEEK. PASSING SHOWERS WILL LIKELY REMAIN FOCUSED
OVER NORTH AND NORTHEAST FACING SLOPES AND BE HIGHLY DEPENDENT ON
MOISTURE LEFT OVER FROM THE FRONT.

MODELS INDICATE THAT ANOTHER ACTIVE WEATHER SYSTEM MAY IMPACT THE
STATE LATE NEXT WEEK BUT DIFFERENCES IN THE MODELS MAKE CONFIDENCE
RATHER LOW ON THE DETAILS.

&&

.AVIATION...
AT 10/0100 UTC A COLD FRONT CONTINUES TO PRODUCE WIDESPREAD MVFR
CONDITIONS ON KAUAI. AIRMET SIERRA REMAINS IN EFFECT FOR MT OBSC
UNTIL CLEARING OCCURS BETWEEN 10/0200-0300 UTC. ELSEWHERE OCNL MVFR
CONDITIONS POSSIBLE OVER MAUI COUNTY/ADJ WTRS IN A PREFRONTAL
CONVERGENT AREA. AWAY FROM THESE AREA MAINLY VFR PREVAILS...HOWEVER
CONDITIONS ON OAHU/ADJ WTRS WILL DETERIORATE OVER THE NEXT 6-12 HRS
SO AIRMET SIERRA WILL SPREAD TO OAHU THIS EVENING. AREAS OF MVFR
VIS/CIGS ARE EXPECTED OVER THE CENTRAL ISLANDS THRU THE PD. CB/TCU
TOPS FL200-FL250.

SRLY FLOW WILL CONTINUE TO PRODUCE LLVL TURB N AND E OF ALL ISLANDS
TONIGHT. WINDS WILL BECOME WRLY OVER KAUAI AFT 10/1000 UTC. CLD WILL
CLEAR OVER THE BIG ISLAND AFT 10/0400Z WITH CLD/SHRA FOCUSED MAINLY
ALG SE SLOPES.

&&

.MARINE...
A NEW ADVISORY LEVEL NORTHWEST SWELL...WILL BUILD ON SUNDAY...PEAK
SUNDAY NIGHT...THEN LOWER SLOWLY ON MONDAY THROUGH TUESDAY. FOR THE
REMAINDER OF NEXT WEEK...THERE WILL BE A SERIES OF NORTH AND
NORTHWEST SWELLS WITH HEIGHTS REMAINING BELOW ADVISORY LEVELS.

WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS
THROUGH TONIGHT. THE ABOVE MENTIONED NORTHWEST SWELL WILL CAUSE SEAS
TO REACH THE SMALL CRAFT ADVISORY THRESHOLD OF 10 FEET SUNDAY AND
SUNDAY NIGHT FOR WATERS EXPOSED TO THIS SWELL. OTHERWISE WINDS AND
SEAS ARE WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE
REST OF THE FORECAST PERIOD.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 6 AM SUNDAY TO 6 PM HST MONDAY FOR NORTH AND
WEST FACING SHORES OF NIIHAU KAUAI OAHU AND MOLOKAI AND NORTH FACING
SHORES OF MAUI.

WIND ADVISORY UNTIL 6 AM HST SUNDAY FOR BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY FROM 6 AM SUNDAY TO 6 PM HST MONDAY FOR ALL
HAWAIIAN WATERS EXCEPT MAALAEA BAY-

&&

SYNOPSIS/DISCUSSION/MARINE...BURKE
AVIATION...DEJESUS