Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 040632
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST TUE MAR 3 2015

.SYNOPSIS...
A TROUGH ALOFT WILL PRODUCE HEAVY RAIN THROUGH WEDNESDAY NIGHT ON
MAUI AND THE BIG ISLAND OF HAWAII. SNOW AND STRONG WINDS WILL LIKELY
AFFECT THE HIGH ELEVATIONS ON THE BIG ISLAND. THE TROUGH WILL ALSO
BRING OVERCAST CLOUDS TO ALL THE ISLANDS. A STRONG SURFACE HIGH TO
THE NORTHWEST WILL KEEP TRADE WINDS BLOWING OVER THE AREA...BRINGING
SCATTERED SHOWERS TO WINDWARD AREAS FROM MOLOKAI TO KAUAI. THE
WEATHER WILL TURN DRIER ON THURSDAY...BUT THAT MAY BE TEMPORARY. THE
TROUGH ALOFT WILL PERSIST THROUGH NEXT WEEK...SO MORE PERIODS OF
STORMY WEATHER ARE POSSIBLE.

&&

.DISCUSSION...
A SURFACE HIGH PRESSURE TO THE NORTHWEST IS PRODUCING MODERATE TO
FRESH TRADE WINDS ACROSS THE ISLANDS. A PERSISTENT TROUGH ALOFT
MADE THE ATMOSPHERE UNSTABLE ENOUGH FOR THUNDERSTORMS TO FORM OVER
THE BIG ISLAND SLOPES WEDNESDAY AFTERNOON. AS OF 800 PM...THE
THUNDER HAD ENDED ON THE BIG ISLAND...BUT THE ATMOSPHERE REMAINS
UNSTABLE. THERE WILL BE A CHANCE OF THUNDERSTORMS OVER THE COASTAL
WATERS AROUND THE BIG ISLAND AND MAUI TONIGHT AND HEAVY SHOWERS WILL
BE POSSIBLE OVER WINDWARD AREAS OF THE BIG ISLAND AND MAUI.
TRADE-WIND WEATHER WILL PERSIST OVER THE SMALLER ISLANDS TONIGHT
WITH SCATTERED SHOWERS MAINLY OVER WINDWARD AREAS. THICK LAYERED
CLOUDS WILL BLANKET THE SKIES OVER ALL THE ISLANDS.

A BROAD AND DEEP TROUGH ALOFT LIES NORTH OF THE AREA. A SHORT-WAVE
TROUGH WITHIN THE LARGER TROUGH IS APPROACHING THE ISLANDS FROM THE
NORTHWEST. AS THE TROUGH GETS CLOSER ON WEDNESDAY...THE ATMOSPHERE
WILL BECOME MORE UNSTABLE AND MOISTURE WILL SPREAD OVER THE ISLANDS
FROM THE SOUTHEAST. MORE HEAVY SHOWERS AND THUNDERSHOWERS ARE LIKELY
WITH THE GREATEST THREAT WEDNESDAY NIGHT ON THE BIG ISLAND. THE
TROUGH ALOFT WILL ALSO LIKELY PRODUCE SNOW OVER THE HIGH ELEVATIONS
ON THE BIG ISLAND. THE RAIN AND SNOW WILL SUBSIDE THURSDAY AS THE
SHORT-WAVE MOVES OFF TO THE NORTHEAST.

THE LARGE-SCALE TROUGH ALOFT WILL PERSIST NORTH OF THE ISLANDS
THROUGH NEXT WEEK. MORE PERIODS OF HEAVY PRECIPITATION ARE POSSIBLE
AS LONG AS THIS TROUGH REMAINS. THE MOST ACTIVE PERIODS WILL COME AS
SHORT WAVE TROUGHS WITHIN THE LARGER TROUGH MOVE OVER THE ISLANDS
FROM THE NORTHWEST. THE GLOBAL MODELS ARE IN GOOD AGREEMENT ON THE
SHORT WAVE AFFECTING THE ISLANDS WEDNESDAY NIGHT BUT THEY DIFFER ON
THE TIMING AND STRENGTH OF SUBSEQUENT SHORT WAVES.

&&

.AVIATION...
AIRMET TANGO IS IN EFFECT FOR HIGH LEVEL TURBULENCE OVER THE AREA
DUE TO THE TROUGH ALOFT. THE TURBULENCE IS LIKELY TO CONTINUE
THROUGH WEDNESDAY AND POSSIBLY LONGER. AIRMET SIERRA IS IN EFFECT
FOR MTN OBSC OVER WINDWARD AREAS OF OF THE BIG ISLAND AND MAUI AND
THOSE CONDITIONS ARE LIKELY TO CONTINUE THROUGH WEDNESDAY. LAYERED
HIGH CLOUDS OVER THE AREA MAY GET THICK ENOUGH TO PRODUCE ICING...
SO AIRMET ZULU FOR ICING MAY BE NEEDED BY WEDNESDAY MORNING. VFR
CONDITIONS WILL PREVAIL FROM LANAI TO KAUAI BUT THERE MAY BE
ISOLATED MVFR CEILINGS OVER WINDWARD AREAS.

&&

.MARINE...
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE COASTAL WATERS
AROUND THE BIG ISLAND AND MAUI TONIGHT. THE CHANCE OF THUNDERSTORMS
MAY INCREASE ON WEDNESDAY. STRENGTHENING NORTHEAST TRADE WINDS HAVE
PROMPTED THE ISSUANCE OF A A SMALL CRAFT ADVISORY FOR STRONG TRADE
WINDS AND ROUGH SEAS STARTING AT 600 AM WEDNESDAY. ROUGH SURF WILL
BUILD ALONG EAST FACING SHORES...AND THIS SURF COULD REQUIRE A HIGH
SURF ADVISORY LATER IN THE WEEK. OTHERWISE...SURF IS EXPECTED TO
REMAIN BELOW THE ADVISORY THRESHOLDS THROUGH THE WEEK. A NORTH
SWELL ARRIVING SUNDAY MAY PRODUCE ADVISORY LEVEL SURF ALONG THE
NORTH FACING SHORES.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY STARTING 600 AM WEDNESDAY FOR THE KAUAI...
KAIWI...MOLOKAI AND ALENUIHAHA CHANNELS...WATERS WEST OF KAUAI...
MAALAEA BAY AND WATERS SOUTH OF THE BIG ISLAND FOR STRONG NORTHEAST
TRADE WINDS AND ROUGH SEAS.

FLASH FLOOD WATCH THROUGH LATE WEDNESDAY NIGHT FOR MAUI AND THE
BIG ISLAND OF HAWAII.

WINTER STORM WARNING UNTIL 600 AM THURSDAY FOR THE SUMMITS OF MAUNA
KEA AND MAUNA LOA.

&&

$$
DONALDSON







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