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Hawaiian Islands Synoptic Discussion and Guidance

242
FXHW60 PHFO 270136
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 PM HST WED NOV 26 2014

.SYNOPSIS...
A RATHER DRY TRADE WIND PATTERN WILL PREVAIL ACROSS MOST OF THE
STATE TONIGHT...BUT LINGERING LOW LEVEL MOISTURE WILL CONTINUE TO
GENERATE SHOWERS ACROSS WINDWARD PORTIONS OF THE BIG ISLAND. A
STRONG HIGH WILL SETTLE NORTH OF THE ISLANDS STARTING
TONIGHT...DRIVING STRONGER TRADE WINDS FOR THE REST OF THE WEEK AND
INTO THE WEEKEND. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA
AREAS.

&&

.DISCUSSION...
FORECAST PHILOSOPHY HAS CHANGED VERY LITTLE SINCE THIS MORNING. A
1027 MB HIGH NEAR 37N170W...FAR NORTHWEST OF THE MAIN HAWAIIAN
ISLANDS...HAS AN ASSOCIATED RIDGE EXTENDING THROUGH 27N160W AND
27N140W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND EQUATORIAL LOW
PRESSURE IS SUFFICIENTLY STEEP TO SUPPORT 15 TO 20 MPH TRADE WINDS
ACROSS MOST LOCAL WATERS. A LATE MORNING ASCAT PASS SHOWED STRONGER
WINDS...IN THE 25 TO 30 MPH RANGE...WITHIN THE ALENUIHAHA CHANNEL
AND ACROSS WATERS SOUTH OF THE BIG ISLAND. AFTERNOON SOUNDINGS SHOW
A STABLE AIRMASS ACROSS THE STATE...WITH CAPE LESS THAN 100 J/KG.
BOTH SOUNDINGS ALSO SHOW A RATHER DRY AIRMASS WITH 1.13 AND 0.98
INCHES OF PW AT HILO AND LIHUE...RESPECTIVELY. SATELLITE LOOP SHOWS
A RATHER TYPICAL TRADE WIND CLOUD DISTRIBUTION...FAVORING WINDWARD
AND MAUKA AREAS. RADAR SHOWS VERY LITTLE PRECIPITATION IS OCCURRING
ACROSS THE STATE. HOWEVER...SURFACE OBSERVATIONS FROM HILO SHOW THAT
AT LEAST LIGHT RAIN IS FALLING FROM THE ABUNDANT LOW CLOUD COVER
THERE.

MOST OF THE STATE SHOULD REMAIN DRY...THANKS TO OUR STABLE AIRMASS
AND A GENERAL LACK OF AVAILABLE MOISTURE. HOWEVER...SCATTERED
SHOWERS WILL REMAIN IN THE FORECAST ACROSS WINDWARD PORTIONS OF THE
BIG ISLAND WHERE A BIT MORE MOISTURE IS AVAILABLE. MODELS SHOW THE
HIGH TO OUR NORTHWEST WILL STRENGTHEN AND MOVE EAST FROM TONIGHT
INTO THE WEEKEND...CAUSING LOCAL TRADE WINDS TO INCREASE INTO THE
FRESH TO STRONG CATEGORY. A TRADE WIND WEATHER PATTERN WILL
PERSIST...WITH CLOUDS AND SHOWERS EXPECTED TO FAVOR WINDWARD AND
MAUKA AREAS. WE MAY SEE A MODEST INCREASE IN WINDWARD SHOWERS ON
FRIDAY...WHEN THE REMNANTS OF AN OLD FRONTAL BOUNDARY REACH THE
STATE. ANOTHER WEAK FRONT MAY APPROACH THE STATE FROM THE NORTHWEST
NEXT TUESDAY OR WEDNESDAY.

&&

.AVIATION...
DRY BREEZY TRADES HAVE LEFT MOST OF THE STATE UNDER VFR CONDITIONS.
THE ONE MAJOR EXCEPTION IS WINDWARD BIG ISLAND WHERE TEMPO MVFR CIGS
IN TRADE SHOWERS ARE EXPECTED TO PERSIST THROUGH THE REMAINDER OF
TODAY AND THROUGH TONIGHT. AIRMET SIERRA FOR MTN OBSC WILL LIKELY
REMAIN NECESSARY THROUGH THURSDAY MORNING.

AIRMET TANGO FOR LOW LEVEL TURBULENCE LEE SIDE OF ALL ISLANDS WILL
LIKELY REMAIN NECESSARY THROUGH THURSDAY MORNING...AND POSSIBLY
BEYOND. THE 8000 FT INVERSION ALOFT WILL PERSIST WHILE LOW LEVEL
WINDS WILL REMAIN FRESH AND GUSTY.

&&

.MARINE...
A NORTH NORTHEAST SWELL WILL PEAK TONIGHT AND...COMBINED WITH
BUILDING WIND WAVES DUE TO INCREASING TRADE WINDS...WILL DRIVE
ADVISORY LEVEL SURF ALONG NORTH AND EAST FACING SHORES THROUGH
THURSDAY AFTERNOON. THIS SWELL MAY ALSO CAUSE HARBOR SURGES WITHIN
KAHULUI AND HILO HARBORS INTO THURSDAY.

A SMALL CRAFT ADVISORY HAS BEEN EXPANDED TO COVER ALL MARINE ZONES
DUE TO A COMBINATION OF STRONG WINDS AND HIGH COMBINED SEAS. THIS
ADVISORY HAS ALSO BEEN EXTENDED THROUGH THURSDAY AFTERNOON.
HOWEVER...ADVISORY CONDITIONS ARE LIKELY TO REMAIN WIDESPREAD ACROSS
HAWAIIAN COASTAL WATERS THROUGH THE REMAINDER OF THIS WEEK AND THE
ADVISORY MAY NEED TO BE EXTENDED AGAIN.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 PM HST THURSDAY FOR ALL HAWAIIAN WATERS.

HIGH SURF ADVISORY UNTIL 6 PM HST THURSDAY FOR ALL NORTH AND EAST
FACING SHORES EXCEPT FOR LANAI AND KAHOOLAWE.

&&

$$

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











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