Flash Flood Warning 36, NWS Honolulu, HI

520 
WGHW70 PHFO 231914
FFSHFO

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE HONOLULU HI
914 AM HST TUE DEC 23 2014

HIC009-231923-
/O.EXP.PHFO.FF.W.0036.000000T0000Z-141223T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MAUI HI-
914 AM HST TUE DEC 23 2014

...THE FLASH FLOOD WARNING HAS EXPIRED FOR THE ISLAND OF MAUI IN MAUI
COUNTY...

WEATHER RADAR AND RAIN GAGES SHOWED THAT THE HEAVY RAINS HAVE ENDED.
THUS THE FLASH FLOOD WARNING IS ALLOWED TO EXPIRE.

LAT...LON 2096 15627 2078 15595 2065 15602 2082 15638

$$

R BALLARD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST TUE DEC 23 2014

.SYNOPSIS...
THUNDERSTORMS ARE LIKELY ACROSS THE MAIN HAWAIIAN ISLANDS AS A
POTENT DISTURBANCE ALOFT DROPS OVER THE STATE. THE POTENTIAL FOR
HEAVY FLOODING RAINFALL AND THUNDERSTORMS...AS WELL AS DANGEROUS
WINTER WEATHER ON THE BIG ISLAND SUMMITS...WILL PERSIST THROUGH AT
LEAST WEDNESDAY. DRIER CONDITIONS ARE EXPECTED THURSDAY AND FRIDAY.

&&

.DISCUSSION...
THE LEADING EDGE OF A SLOW-MOVING FRONT WILL REMAIN NEAR THE BIG
ISLAND THROUGH TODAY. A STRONG MID TO UPPER LEVEL TROUGH APPROACHING
THE MAIN HAWAIIAN ISLANDS FROM THE NORTHWEST IS RAPIDLY
DESTABILIZATION THE ATMOSPHERE...RAISING THE PROBABILITY FOR
THUNDERSTORMS.

A STRONG MID TO UPPER LEVEL TROUGH CURRENTLY JUST NORTHWEST OF KAUAI
WILL MOVE OVER THE ISLANDS TODAY. WHILE THE GREATEST THUNDERSTORM
THREAT WILL BE ALONG AND JUST WEST OF THE FRONT NEAR THE BIG
ISLAND...THUNDERSTORMS COULD POP UP ANYWHERE WITHIN THE UPPER TROUGH
OVER THE WESTERN ISLANDS. THESE THUNDERSTORMS COULD BE STRONG WITH
THE POTENTIAL TO PRODUCE HAZARDOUS LIGHTNING...STRONG AND GUSTY
WINDS...HAIL...AND HEAVY RAINFALL.

THE THREAT FOR HEAVY SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGH
AT LEAST WEDNESDAY AS THE TROUGH ALOFT FORMS A STRONG CUTOFF LOW.
THE FRONTAL BOUNDARY WILL LIKELY WASH OUT THROUGH THE DAY TODAY.
HOWEVER...THE CUTOFF LOW WILL MEANDER NEARBY...AND MODELS DEPICT
DEEP MOISTURE BEING DRAWN OVER THE ISLANDS FROM THE SOUTHEAST WITH A
SURFACE LOW POSSIBLY DEVELOPING OVER THE ISLANDS. THE THREAT FOR
HEAVY FLOODING RAINFALL WITH THUNDERSTORMS WILL CONTINUE THROUGH AT
LEAST WEDNESDAY...AND A FLASH FLOOD WATCH REMAINS IN PLACE THROUGH
WEDNESDAY AFTERNOON.

HAZARDOUS WEATHER IS ALSO POSSIBLE OVER THE BIG ISLAND SUMMITS. AS
THE UPPER LEVEL TROUGH MOVES EASTWARD AND FORMS A CUTOFF LOW...VERY
WINDY CONDITIONS WILL OCCUR ON THE HIGH BIG ISLAND SUMMITS...AND A
HIGH WIND WARNING REMAINS IN EFFECT. AS DEEP MOISTURE IS DRAWN
TOWARD THE STATE TODAY...PERIODS OF HEAVY SNOW ARE POSSIBLE. IN
COMBINATION WITH THE STRONG WINDS ALREADY IN PLACE...BLIZZARD
CONDITIONS ARE POSSIBLE BUT ARE BY NO MEANS CERTAIN AT THIS TIME.
JUST IN CASE...A BLIZZARD WATCH REMAINS IN EFFECT THROUGH WEDNESDAY
AFTERNOON.

MOST FORECAST MODELS DEPICT THE CUTOFF LOW AND ANY ASSOCIATED LOW
LEVEL FEATURE LIFTING OFF TO THE NORTHEAST ON THURSDAY. NORTHERLY
LOW LEVEL WINDS ARE EXPECTED ALONG WITH A DECREASE IN RAINFALL.
HOWEVER...THE GFS AND ECMWF ARE SHOWING ANOTHER SHORTWAVE ALOFT
DROPPING NEARBY ON FRIDAY INTO SATURDAY...POSSIBLY TRIGGERING SOME
INSTABILITY.

&&

.AVIATION...
THE SURFACE FRONT NEAR THE BIG ISLAND WILL CONTINUE TO DRIFT
SOUTHEAST AND GRADUALLY WEAKEN. RAIN...HEAVY AT TIMES...WILL PERSIST
ACROSS MAUI COUNTY AND SPREAD ACROSS THE BIG ISLAND BY AFTERNOON. A
DRIER AIR MASS HAS MOVED INTO KAUAI AND OAHU AND SHOWERS IN THESE
AREAS ARE BEGINNING TO TAPER OFF. AIRMET SIERRA FOR MTN OBSCURATION
FOR MAUI COUNTY SHOULD REMAIN NECESSARY THROUGH THIS EVENING AND
WILL LIKELY BE EXPANDED TO INCLUDE WINDWARD OAHU BY THIS AFTERNOON.
AIRMET SIERRA FOR MTN OBSCURATION WILL LIKELY BE CANCELLED LATER
THIS MORNING. AREAS OUTSIDE THE MOUNTAIN OBSCURATION MAY SEE
OCCASIONAL MVFR CONDITIONS.

STRONG AND GUSTY NORTH WINDS ALONG AND TO THE WEST OF THE FRONT HAVE
NECESSITATED THE ISSUANCE OF AIRMET TANGO FOR LOW LEVEL TURBULENCE.
TANGO INCLUDES KAUAI OAHU MOLOKAI LANAI MAUI...AND MAY NEED TO BE
EXPANDED TO INCLUDE THE BIG ISLAND LATER TODAY.

MEANWHILE A COLD UPPER LEVEL TROUGH MOVING IN FROM THE NW HAS
CREATED THE POTENTIAL FOR UPPER LEVEL TURBULENCE OVER KAUAI.
CONDITIONS ARE EXPECTED TO SPREAD ACROSS OAHU LATER THIS MORNING AND
REACH MAUI COUNTY LATER THIS AFTERNOON.

THE COLD UPPER LEVEL TROUGH WILL ALSO SERVE TO FURTHER DESTABILIZE
THE AIR MASS OVER THE STATE. THUNDERSTORM POTENTIAL THIS MORNING
WILL BE FOCUSED MAINLY ALONG AND JUST TO THE WEST OF THE SURFACE
FRONT BUT BY AFTERNOON THE THREAT OF THUNDERSTORMS...INCLUDING
SEVERE THUNDERSTORMS...WILL EXPAND TO INCLUDE THE WHOLE OF THE
STATE. AVIATION HAZARDS ASSOCIATED WITH ACTIVE THUNDERSTORMS INCLUDE
ICING...TURBULENCE...WIND SHEAR AND IFR CONDITIONS.

&&

.MARINE...
STRONG NORTH-NORTHEAST WINDS ARE BLOWING ACROSS THE WESTERN HALF OF
THE ISLAND CHAIN BEHIND A SLOW-MOVING FRONT NEAR THE BIG ISLAND.
LARGE SEAS GENERATED BY THESE WINDS WILL COMBINE WITH A LARGE
NORTHWEST SWELL TO PRODUCE HAZARDOUS CONDITIONS...AND A SMALL CRAFT
ADVISORY IS IN EFFECT FOR ALL WATERS DUE TO THESE THREATS.

THE NORTHWEST SWELL HAS DIMINISHED OVERNIGHT AND THE HIGH SURF
WARNING HAS BEEN DOWNGRADED TO AN ADVISORY. WE EXPECT ADVISORY LEVEL
SURF WILL ALSO OCCUR ALONG SOME EAST FACING SHORES EXPOSED TO
NORTHERLY SWELL. NORTH AND EAST PORTIONS OF THE BIG ISLAND MAY BE
ADDED TO THIS ADVISORY LATER TODAY IF EASTERLY WINDS PRODUCE
SUFFICIENTLY HIGH CHOPPY SURF CONDITIONS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR ALL HAWAII ISLANDS.

HIGH SURF ADVISORY UNTIL 6 AM HST WEDNESDAY FOR NIIHAU-KAUAI
WINDWARD-KAUAI LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-OAHU
KOOLAU-OLOMANA-MOLOKAI-MAUI WINDWARD WEST-MAUI CENTRAL VALLEY-
WINDWARD HALEAKALA-KONA-KOHALA.

HIGH WIND WARNING THROUGH 6 AM HST THURSDAY FOR BIG ISLAND SUMMITS.

BLIZZARD WATCH THROUGH WEDNESDAY AFTERNOON FOR BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR ALL HAWAIIAN
WATERS.

&&

DISCUSSION/MARINE...POWELL
AVIATION...BEDAL