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Hawaiian Islands Synoptic Discussion and Guidance

642
FXHW60 PHFO 280159
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
359 PM HST THU NOV 27 2014

.SYNOPSIS...
A RATHER DRY TRADE WIND PATTERN WILL PREVAIL ACROSS MOST OF THE
STATE THROUGH THE NEXT COUPLE OF DAYS...BUT LINGERING LOW LEVEL
MOISTURE WILL CONTINUE TO GENERATE SCATTERED SHOWER ACTIVITY
ACROSS WINDWARD PORTIONS OF THE BIG ISLAND AND MAUI. SURFACE HIGH
PRESSURE NORTH OF THE ISLANDS WILL DRIVE STRONG TRADE WINDS
ACROSS THE STATE THROUGH THE END OF THIS WEEK AND INTO THE
WEEKEND. TRADES SHOULD SLACKEN A BIT EARLY NEXT WEEK...WITH
SHOWERS REMAINING FOCUSED MAINLY ACROSS WINDWARD AREAS.

&&

.DISCUSSION...
DRY AND STABLE CONDITIONS HAVE CONTINUED ACROSS MOST OF THE STATE
TODAY. VISIBLE SATELLITE SHOWS LOW CLOUDS BANKED AGAINST MOST OF
THE WINDWARD SLOPES...PARTICULARLY ACROSS MAUI AND THE BIG ISLAND.
BOTH WINDWARD MAUI AND BIG ISLAND PICKED UP SMALL AMOUNTS OF
RAIN...BUT THE REST OF THE STATE HAS ESSENTIALLY BEEN DRY. THE
00Z LIHUE SOUNDING FOUND A DRY AND VERY STABLE PROFILE...WITH A
STRONG INVERSION BASED NEAR 5000 FEET AND PRECIPITABLE WATER /PW/
OF ONLY 0.94 INCHES. THE HILO SOUNDING REFLECTED THE SLIGHTLY
DEEPER MOISTURE LINGERING NEAR THE BIG ISLAND...WITH AN INVERSION
BASED AROUND 8000 FEET AND 1.09 INCHES OF PW. MIMIC-TOTAL PW
SATELLITE IMAGERY REFLECTS THESE DIFFERENCES BETWEEN THE NORTHERN
END OF THE STATE AND THE SOUTH.

SURFACE ANALYSIS DEPICTS A 1029 MB HIGH CENTERED 1050 MILES NORTH
OF KAUAI. THE HIGH IS FUNNELING FRESH TO LOCALLY STRONG TRADE
WIND FLOW OVER HAWAII. SUSTAINED WINDS TODAY HAVE BEEN HOVERING
JUST UNDER THE WIND ADVISORY MARK...AROUND 20 TO 25 MPH...IN
EXPOSED AREAS AROUND MAUI COUNTY AND THE BIG ISLAND. MODELS DEPICT
A SIMILAR GRADIENT ACROSS THE STATE TOMORROW AND SATURDAY AS THE
HIGH PRESSURE SYSTEM SLOWLY SHIFTS EASTWARD. GIVEN THIS
SCENARIO...WILL DROP ALL THE WIND ADVISORIES AND EXPECT LITTLE
CHANGE IN WIND SPEEDS FOR FRIDAY AND SATURDAY.

OTHERWISE...SPARSE SHOWER COVERAGE WILL BE MAINLY CONFINED TO WINDWARD AND
MAUKA AREAS THROUGH THE WEEKEND...WITH THE BEST RAIN CHANCES
REMAINING ACROSS THE WINDWARD BIG ISLAND. BLENDED MODEL DATA KEEPS
PW NEAR OR BELOW ONE INCH (BELOW THE 25TH PERCENTILE FOR THIS
TIME OF YEAR). THEREFORE WOULD EXPECT RAINFALL AMOUNTS TO REMAIN
MOSTLY ON THE LIGHT SIDE.

TRADE WINDS SHOULD SLACKEN A BIT EARLY NEXT WEEK...AS THE SURFACE
HIGH TO OUR NORTH WEAKENS. A MODEST INCREASE IN LOW LEVEL MOISTURE
MAY TAKE PLACE...AND A VERY WEAK FRONT OR SHEAR LINE MAY PASS
THROUGH THE STATE AROUND NEXT WEDNESDAY. WITH THE ADDED MOISTURE
WINDWARD/MAUKA SHOWERS COULD INCREASE SOMEWHAT...BUT OVERALL DO NOT
EXPECT ANY MAJOR CHANGES TO THE WEATHER PATTERN.


&&

.AVIATION...
FRESH AND GUSTY TRADE WINDS BENEATH A WELL DEFINED INVERSION ALOFT
ARE EXPECTED TO PERSIST THROUGH 24 HOURS AND BEYOND. WIND SPEEDS IN
EXCESS OF 25 KT ARE EXPECTED ALONG NORTHEASTERN EXPOSURES AND OVER
MOUNTAIN RIDGES. CHANNELED AREAS MAY EXPERIENCE STRONGER WINDS.
AIRMET TANGO FOR MODERATE LOW LEVEL TURB LEE SIDE OF ALL MOUNTAINS
IS LIKELY TO REMAIN NECESSARY THROUGH 24 HOURS AND POSSIBLY BEYOND.

PRECIPITATION IS EXPECTED TO REMAIN LIGHT AND MAINLY CONFINED TO
WINDWARD PORTIONS OF MAUI AND THE BIG ISLAND. HOWEVER ISOL MVFR CIGS
IN PASSING SHOWERS THIS AFTERNOON COULD BECOME MORE NUMEROUS ACROSS
THE NORTHEAST BIG ISLAND COAST LATER THIS EVENING. WILL MONITOR FOR
POSSIBLE DVLPG MTN OBSC. OTHERWISE VFR CONDS EXPECTED TO PREVAIL ALL
OTHER AREAS THROUGH FRIDAY AFTERNOON.

&&

.MARINE...
THE CURRENT NORTH-NORTHEAST SWELL IS SLOWLY TAPERING OFF THIS
AFTERNOON. THIS SWELL IS EXPECTED TO REMAIN ELEVATED OVER THE NEXT
SEVERAL DAYS AS IT GRADUALLY TRANSITIONS TO A NORTHEAST SWELL
MONDAY. THE HIGH SURF ADVISORY HAS BEEN DROPPED FOR NORTH FACING
SHORES...BUT REMAINS IN EFFECT FOR EAST FACING SHORES OF
KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND THROUGH FRIDAY AT
6 PM. THE SWELL COMBINED WITH THE LOCAL WIND WAVES OVER HAWAII
MAY RESULT OF A CONTINUATION OF THE HIGH SURF ADVISORY FOR EAST
FACING SHORES THROUGH THE WEEKEND.

THE CURRENT NORTH-NORTHEAST SWELL MAY ALSO CAUSE HARBOR SURGES
WITHIN KAHULUI AND HILO HARBORS THROUGH THROUGH FRIDAY. A MARINE
WEATHER STATEMENT HAS BEEN ISSUED TO COVER THIS THREAT.

THE SMALL CRAFT ADVISORY /SCA/ HAS BEEN EXPANDED TO COVER ALL
HAWAIIAN COASTAL WATERS EXCEPT THE LEEWARD MAUI ZONE THROUGH 6PM
TOMORROW DUE TO A COMBINATION OF WINDS AND SEAS. THE NORTH-
NORTHEAST SWELL AND LOCAL WIND WAVES WILL LIKELY KEEP SOME OF THE
ZONES IN THE SCA INTO THIS WEEKEND.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM HST FRIDAY FOR EAST FACING SHORES
OF KAUAI OAHU MOLOKAI AND MAUI.

SMALL CRAFT ADVISORY FOR ALL HAWAIIAN COASTAL WATERS EXCEPT
LEEWARD MAUI WATERS UNTIL 6 PM HST FRIDAY.

SMALL CRAFT ADVISORY THEN CONTINUES UNTIL 6 AM HST SATURDAY FOR
KAUAI NORTHWEST WATERS-KAUAI CHANNEL-OAHU LEEWARD WATERS-KAIWI
CHANNEL- MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND
LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.


&&

$$

DISCUSSION/MARINE...FOSTER
AVIATION...BEDAL


Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office