Heavy Rain in Hawaii, April 13 to 14, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
836 AM HST SAT APR 13 2013

.SYNOPSIS...
CHANCES OF THUNDERSTORMS AND LOCALLY HEAVY RAIN WILL CONTINUE OVER
THE WESTERN ISLANDS TODAY AND TONIGHT AS A COLD FRONT MOVES IN FROM
THE WEST. CHANCES OF SHOWERY CLOUDY WEATHER WILL PERSIST OVER KAUAI
AND OAHU INTO EARLY NEXT WEEK NEAR THE STALLED COLD FRONT. LIGHT TO
MODERATE TRADE WINDS ARE SET TO RETURN WEDNESDAY THROUGH THE
REMAINDER OF THE COMING WEEK.

&&

.DISCUSSION...
STRONG DEEP LAYERED LOW PRESSURE IS POSITIONED NW OF HAWAII THIS
MORNING. THE ATTENDANT SURFACE COLD FRONT IS JUST OUTSIDE THE KAUAI
COASTAL WATERS AND WILL REMAIN THE FOCUS FOR TSTORMS AND HEAVY RAIN
FOR KAUAI/NIIHAU OVER THE NEXT SEVERAL HOURS. SOME STORMS MAY BE
SEVERE SO A SEVERE TSTORM WATCH HAS BEEN ISSUED FOR KAUAI AND
ADJACENT WATERS THROUGH 2 PM TODAY. THE THREAT WILL SPREAD E TO
OAHU LATER THIS AFTERNOON AND EVENING BUT THE POSSIBILITIES OF
SEVERE TSTORMS WILL HAVE DIMINISHED. THE FLASH FLOOD WATCH REMAINS
IN EFFECT THROUGH TONIGHT FOR NIIHAU KAUAI AND OAHU. CONDITIONS
ALOFT SUPPORTING THE FLASH FLOOD/TSTORM THREAT WILL WEAKEN TOMORROW
HOWEVER RAINY WEATHER WILL CONTINUE FOR THE WESTERN ISLANDS ALONG
THE STALLED FRONTAL BOUNDARY. BREAKS IN THE CLOUDS ALLOWING FOR
AREAS OF BETTER INSOLATION MAY STILL PRODUCE HEAVY DOWNPOURS SUN
AFTERNOON. THE WIND ADVISORY FOR THE BIG ISLAND SUMMITS EXPIRES AT
NOON BUT MAY NEED AN EXTENSION AS GUSTY W WINDS OVER 30 MPH MAY
PERSIST.

LIGHT SE FLOW COUPLED WITH LINGERING MOISTURE ALONG THE DECAYING
FRONT WILL SUSTAIN HIGH RAINFALL CHANCES FOR THE WESTERN ISLANDS
MON-TUE. DIURNAL TENDENCIES MAY PROVIDE THE FORCING NECESSARY FOR
BRIEF HEAVY LEEWARD DOWNPOURS EACH AFTERNOON. REMNANT MOISTURE
SHOULD BEGIN TO LIFT OUT TUE NIGHT-WED AS ENPAC HIGH PRESSURE
STRENGTHENS SIGNALING THE RETURN OF LEAST NOMINAL TRADE FLOW LOCALLY
WED. GUIDANCE REMAINS IN FAIR AGREEMENT SYNOPTICALLY SUGGESTING AT
LEAST LIGHT-MODERATE TRADES MID WEEK...POSSIBLY PERSISTING INTO THE
FOLLOWING WEEKEND. LONGER TERM CERTAINTY REMAINS LOW.

&&

.AVIATION...
FRONT WEST OF KAUAI PRODUCING THUNDERSTORMS OVER COASTAL WATERS WEST
OF KAUAI THIS MORNING. SOME THUNDERSTORMS COULD BE SEVERE THROUGH
EARLY AFTERNOON...AND SIGMET NOVEMBER SERIES IS IN PLACE NEAR KAUAI.
THERE IS ENOUGH LOW CLOUD TO WARRANT MTN OBSC ON KAUAI AT THIS
TIME...AND AS THE FRONT SLOWLY ADVANCES EASTWARD TODAY...EXPECT MTN
OBSC TO REMAIN IN PLACE DUE TO MVFR CIGS AND LOWERED VIS IN SHRA.
ONLY ISOL MVFR CIGS ELSEWHERE THIS MORNING IN A S TO SE LOW LVL
FLOW. AIRMET TANGO ALSO IN PLACE FOR ICING IN LYR 115-170 AROUND
KAUAI TODAY. OAHU COULD SEE MTN OBSC AND ICING LATER TODAY INTO
TONIGHT AS THE FRONT MOVES EASTWARD.

&&

.MARINE...
STRONG-SEVERE TSTORMS CONTINUE OVER THE KAUAI COASTAL WATERS AND
ADJACENT WESTERN OFFSHORE ZONE. FREQUENT LIGHTNING...SMALL HAIL AND
GUSTY WINDS ARE LIKELY. BRIEF HIGHER SEAS AND REDUCED VISIBILITY
WILL ALSO ACCOMPANY THE STRONGEST STORMS. THIS THREAT WILL GRADUALLY
MOVE E TOWARDS OAHU WATERS INTO TONIGHT. MARINE WEATHER STATEMENTS
ARE POSTED HIGHLIGHTING THIS THREAT THROUGH NOON...BUT MAY BE
EXTENDED.

SMALL WNW SWELL WILL PRODUCE MODEST SURF ALONG EXPOSED BEACHES THIS
WEEKEND. ANOTHER SLIGHTLY LARGER SWELL WILL ARRIVE FOR THE SECOND
HALF OF NEXT WEEK. NO SMALL CRAFT ADVISORIES ARE EXPECTED IN THE
NEAR TERM.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH 6 AM HST SUNDAY FOR KAUAI...NIIHAU AND
OAHU.

WIND ADVISORY BIG ISLAND SUMMITS UNTIL NOON HST TODAY.

&&

PUBLIC/MARINE...DEJESUS
AVIATION...WROE
PREVIOUS...HUI/HOUSTON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HONOLULU HI
942 AM HST SAT APR 13 2013

HIZ002>004-132045-
KAUAI WINDWARD-KAUAI LEEWARD-KAUAI MOUNTAINS-
942 AM HST SAT APR 13 2013

A LINE OF STRONG THUNDERSTORMS WILL MOVE ACROSS KAUAI FROM THE
WEST BY 945 AM HST NEAR BARKING SANDS AND MOVE SLOWLY EASTWARD
THROUGH 1045 AM. STRONG AND GUSTY WINDS AROUND 40 MPH AND FREQUENT
LIGHTNING WILL ACCOMPANY THE LINE.

WROE