High Surf in Hawaii, November 26 to 27, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST SAT NOV 26 2011

.SYNOPSIS...
A FRONT MOVING DOWN THE ISLANDS WILL BRING SCATTERED SHOWERS TONIGHT
AND STRONG AND GUSTY NORTHEAST WINDS THROUGH SUNDAY. A LARGE NORTH
NORTHWEST SWELL COMBINED WITH THE LOCALLY GENERATED WIND WAVES WILL
PRODUCE ROUGH SURF. THE WEATHER WILL DRY OUT RAPIDLY ON SUNDAY AS
THE FRONT MOVES SOUTH AND DISSIPATES. THE WINDS WILL DIMINISH
STARTING SUNDAY EVENING AS A NEW FRONT APPROACHES FROM THE NORTHWEST.

&&

.DISCUSSION...
A FRONTAL CLOUD BAND WHOSE LEADING EDGE WAS OVER MAUI LATE THIS
AFTERNOON WILL MOVE SOUTH SOUTHEAST AROUND 10 MPH AND WEAKEN THROUGH
TONIGHT. THE BAND SHOULD CLEAR THE ISLANDS BY EARLY SUNDAY MORNING.
THE ATMOSPHERE OVER THE ISLANDS IS RELATIVELY STABLE...AND QUITE DRY
ABOVE A STRONG INVERSION AROUND 7000 FT. WITH THE ATMOSPHERE THIS
STABLE AND THE MOIST LAYER SO SHALLOW THE FRONTAL BAND WILL PRODUCE
ONLY MODEST RAINFALL AMOUNTS.

A RELATIVELY STRONG 1031 MB HIGH 935 MILES NORTH OF KAUAI NEAR
36N161W WILL MAINTAIN A TIGHT PRESSURE GRADIENT BEHIND THE FRONT
THROUGH SUNDAY AS THE HIGH MOVES EAST AT 25 MPH. THE WINDS WILL BE
ACCELERATED LOCALLY AS THE WINDS FUNNEL AROUND THE MOUNTAINOUS
TERRAIN CAPPED BY A STRONG LOW-LEVEL TEMPERATURE INVERSION. THESE
WINDS WILL BE STRONG ENOUGH TO PRODUCE GALES IN THE PAILOLO AND
ALENUIHAHA CHANNELS AND GUSTS STRONG ENOUGH TO REQUIRE WIND
ADVISORIES OVER SOME AREAS OF MAUI COUNTY AND THE BIG ISLAND.

THE GLOBAL MODELS ARE IN GOOD AGREEMENT THROUGH EARLY NEXT WEEK
SHOWING THE SURFACE HIGH MOVING OFF TO THE EAST AS A NEW FRONT
APPROACHES FROM THE NORTHWEST. THE MODELS ALSO SHOW A SURFACE TROUGH
DEVELOPING EAST OF THE STATE.
THESE CHANGES WILL CAUSE THE PRESSURE GRADIENT OVER THE ISLANDS TO
SLACKEN STARTING SUNDAY NIGHT. WINDS WILL BECOME GENTLE TO MODERATE
TRADES BY TUESDAY AND REMAIN GENTLE TO MODERATE THROUGH NEXT WEEK.
THE ATMOSPHERE WILL REMAIN DRY AND STABLE THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK SO RAINFALL SHOULD BE BELOW NORMAL. TOWARD THE
END OF NEXT WEEK INCREASED LOW LEVEL MOISTURE AND ATMOSPHERIC
INSTABILITY MAY CAUSE RAINFALL TO INCREASE...BUT THAT IS STILL FAR
FROM CERTAIN.

&&

.MARINE...
AS THE FRONT MOVES SOUTHEAST THROUGH THE COASTAL WATERS...WINDS WILL
REMAIN ABOVE THE 25 KT THRESHOLD FOR ALL COASTAL WATERS AND AT GALE
FORCE IN THE PAILOLO AND ALENUIHAHA CHANNELS TONIGHT THROUGH SUNDAY.
WINDS WILL DIMINISH FAIRLY RAPIDLY STARTING SUNDAY NIGHT AS THE
SURFACE HIGH MOVES RAPIDLY EAST AND A FRONT APPROACHES FROM THE
NORTHWEST. SMALL CRAFT ADVISORIES MAY BE DROPPED AS EARLY AS MONDAY
NIGHT.

A LARGE NORTH NORTHWEST SWELL WILL PRODUCE HIGH SURF ALONG NORTH AND
WEST FACING SHORES WHILE THE STRONG NORTHEAST WINDS WILL PRODUCE
ROUGH SURF ALONG EAST FACING SHORES. A HIGH SURF ADVISORY IS LIKELY
TO REMAIN UP FOR AFFECTED COASTLINES THROUGH SUNDAY AFTERNOON.
COASTAL FLOODING AND BEACH EROSION MAY BE A PARTICULAR PROBLEM ALONG
NORTHEAST FACING BEACHES AS WAVE RUN UP IS ENHANCED BY THE STRONG
NORTHEAST WINDS. THIS WILL BE ESPECIALLY LIKELY DURING HIGH TIDES.
THE LARGEST ASTRONOMICAL HIGH TIDE WILL BE JUST BEFORE SUNRISE ON
SUNDAY MORNING. A MARINE WEATHER STATEMENT REMAINS UP FOR POSSIBLE
HARBOR SURGES EXPOSED TO THE LARGE NORTHEAST SWELL.

&&

.AVIATION...
AIRMET TANGO WILL LIKELY REMAIN UP THROUGH SUNDAY AND POSSIBLY
LONGER FOR MODERATE LOW LEVEL TURBULENCE SOUTH THROUGH WEST OF THE
MOUNTAINS. SIGMETS MAY BE REQUIRED AT TIMES FOR SEVERE LOW LEVEL
TURBULENCE. THE CLOUD BAND ALONG THE FRONT WILL BRING MVFR CEILINGS
AND VISIBILITIES WITH SHRA AS IT MOVES ACROSS MAUI COUNTY AND THE
BIG ISLAND TONIGHT.

&&

.FIRE WEATHER...
STRONG NORTHEAST WINDS AND VERY DRY AIR FILLING IN BEHIND THE FRONT
MAY PRODUCE CONDITIONS FAVORABLE FOR RAPID FIRE GROWTH SUNDAY. A
RED FLAG WARNING HAS BEEN ISSUED FOR SUNDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...

RED FLAG WARNING FOR SUNDAY.

WIND ADVISORY THROUGH TONIGHT FOR PARTS OF THE BIG ISLAND AND MAUI
COUNTY.

HIGH SURF ADVISORY THROUGH SUNDAY AFTERNOON FOR NORTH AND EAST
FACING SHORES OF LANAI AND THE BIG ISLAND AND NORTH...EAST AND WEST
FACING SHORES OF THE OTHER ISLANDS.

GALE WATCH FROM THROUGH SUNDAY AFTERNOON FOR THE PAILOLO AND
ALENUIHAHA CHANNELS.

SMALL CRAFT ADVISORY THROUGH SUNDAY AFTERNOON FOR THE REST OF THE
HAWAIIAN WATERS.

&&

DONALDSON