Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 061359
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
359 AM HST SAT FEB 6 2016

.SYNOPSIS...
FAIR AND MOSTLY DRY WEATHER WILL PREVAIL ACROSS THE STATE THROUGH
MUCH OF TODAY. A STRONG COLD FRONT WILL REACH KAUAI LATE THIS
AFTERNOON...THEN SWEEP SOUTHEAST THROUGH THE REMAINDER OF THE
STATE TONIGHT INTO SUNDAY MORNING...BRINGING WIDESPREAD SHOWERS
AND GUSTY NORTH WINDS. WINDY...COOL AND DRY WEATHER WILL SPREAD
OVER THE ISLANDS BEHIND THE FRONT. WINDS WILL DECREASE MONDAY AS
WEAKENING HIGH PRESSURE SETTLES SOUTHWARD TOWARD THE ISLANDS...
THEN GENTLE TRADE WINDS WILL PREVAIL THROUGH THE MIDDLE OF THE
WEEK AS WEAK HIGH PRESSURE LINGERS NORTH OF THE STATE.

&&

.DISCUSSION...
AN AREA OF CLOUDINESS ALONG WITH WIDELY SCATTERED LIGHT SHOWERS
CONTINUES TO LINGER ACROSS THE CENTRAL ISLANDS EARLY THIS
MORNING. CLOUDINESS AND SCATTERED SHOWERS ALSO PERSIST SOUTHEAST
OF THE BIG ISLAND. MOSTLY CLEAR AND DRY CONDITIONS PREVAIL
ELSEWHERE ACROSS THE STATE. SURFACE ANALYSIS DEPICTS A WELL-
DEFINED COLD FRONT LOCATED ABOUT 250 MILES NORTHWEST OF KAUAI
AS OF 3 AM. THIS FRONT IS MOVING QUICKLY TO THE SOUTHEAST AT ABOUT
25 MPH. HIGH PRESSURE IS BUILDING EASTWARD ACROSS THE
INTERNATIONAL DATELINE BEHIND THIS FRONT. ALOFT...A MID-LATITUDE
TROUGH AXIS IS LOCATED ALONG 165W AND IS MOVING QUICKLY
EASTWARD...SUPPORTING THE SURFACE COLD FRONT. THE 12Z SOUNDINGS
AT LIHUE AND HILO SHOW DRY AND STABLE CONDITIONS PRESENT AHEAD OF
THE FRONT...WITH INVERSIONS BASED AROUND 5K FEET AND PWATS NEAR
0.85 INCHES...ALTHOUGH MIMIC-TPW SATELLITE IMAGERY DOES SHOW AN
AREA OF HIGHER MOISTURE WITH ESTIMATED PWATS UP TO 1.4 INCHES OVER
THE CENTRAL ISLANDS.

GENTLE WINDS AND MOSTLY DRY CONDITIONS WILL CONTINUE ACROSS THE
STATE TODAY AHEAD OF THE ADVANCING COLD FRONT. THE LIGHT
BACKGROUND FLOW WILL ALLOW SEA BREEZES TO DEVELOP...ALONG WITH
CLOUDS AND SOME LIGHT SHOWERS. THE ADVANCING COLD FRONT APPEARS TO
BE ON TRACK TO REACH KAUAI LATE THIS AFTERNOON...OAHU EARLY THIS
EVENING...MAUI COUNTY DURING THE NIGHT...AND THE BIG ISLAND BY
EARLY SUNDAY MORNING. THIS FRONT WILL BRING A TEMPORARY INCREASE
IN CLOUDS AND SHOWERS...BUT STRONG NORTHERLY WINDS BEHIND THE
FRONT WILL BE THE PRIMARY WEATHER CONCERN. WE HAVE POSTED A WIND
ADVISORY FOR KAUAI/NIIHAU BEGINNING AT 2PM THIS AFTERNOON...AND
FOR OAHU BEGINNING AT 6PM THIS EVENING. THIS ADVISORY WILL RUN
THROUGH SUNDAY AFTERNOON. SUSTAINED WINDS UP TO 30 MPH AND WIND
GUSTS UP TO 55 MPH ARE FORECAST...WITH THE STRONGEST WINDS LIKELY
DOWNWIND OF HIGHER TERRAIN AND IN NORTH-FACING VALLEYS. THE WIND
ADVISORY MAY NEED TO BE EXPANDED ACROSS PARTS OF MAUI COUNTY AND
THE BIG ISLAND LATER AS THE STRONG WINDS ARE FORECAST TO SPREAD
OVER THOSE AREAS OVERNIGHT INTO SUNDAY...BUT WILL LET THE DAY
SHIFT MAKE THAT DETERMINATION.

THE COOLEST AIRMASS OF THE SEASON WILL SPREAD INTO THE STATE
BEHIND THE FRONT AND LINGER INTO EARLY NEXT WEEK. DEWPOINTS WILL
DROP WELL INTO THE 50S...AND OVERNIGHT LOWS WILL BE QUITE COOL
WITH MANY AREAS SEEING READINGS IN THE LOWER TO MID 60S...AND
MID TO UPPER 50S AT SOME LOCATIONS EVEN IN THE LOWER ELEVATIONS.
SUNDAY AND MONDAY NIGHTS WILL SEE THE COOLEST TEMPERATURES.
DAYTIME HIGHS SUNDAY AND MONDAY WILL BE RATHER COOL AS WELL...
WITH HIGHS ONLY IN THE 70S FOR MOST AREAS.

WINDS WILL DECREASE ACROSS THE STATE ON MONDAY AS HIGH PRESSURE
WEAKENS AND SETTLES SOUTHWARD TO NEAR KAUAI. IT APPEARS THAT A
WEAK RIDGE WILL THEN REMAIN JUST NORTH OF THE STATE THROUGH MUCH
OF NEXT WEEK...MAINTAINING GENTLE TRADE WIND FLOW OVER THE
ISLANDS. THE LATEST GFS AND ECMWF KEEP THE NEXT FRONT NORTH OF
THE STATE AROUND MIDWEEK...ALTHOUGH THE EARLIER 00Z GFS RUN
BROUGHT THE TAIL END OF THE FRONT OR SHEAR LINE THROUGH THE
WESTERN ISLANDS DURING THAT TIME. OTHERWISE...A DRY AND STABLE
AIRMASS WILL REMAIN OVER THE STATE THROUGH NEXT WEEK...WITH
LITTLE RAINFALL EXPECTED.

&&

.AVIATION...
VFR WILL PREVAIL OVER THE ISLAND CHAIN THROUGH THE AFTERNOON
HOURS...WITH ONLY ISOLATED POCKETS OF MVFR. A FRONT WILL BRING GUSTY
NORTH WINDS AND GREATER CHANCES OF MVFR TO KAUAI BY THE LATE
AFTERNOON...AND TO OTHER PARTS OF THE STATE LATER AS THE FRONT MOVES
EAST.

NO AIRMETS ARE CURRENTLY IN EFFECT. HOWEVER...AN AIRMET FOR LOW
LEVEL TURBULENCE WILL LIKELY BE ISSUED LATER TODAY AS THE FRONT
PUSHES INTO THE AREA...AND ONE POSSIBLY FOR MOUNTAIN OBSCURATION.

&&

.MARINE...
THE LATEST ASCAT PASS AROUND MIDNIGHT SHOWED 20 TO 25 KT NORTHWEST
WINDS IN THE WAKE OF A COLD FRONT THAT WAS LOCATED AROUND 200 MILES
NORTHWEST OF KAUAI. THIS BOUNDARY WILL QUICKLY SWEEP THROUGH THE
STATE LATER TODAY THROUGH SUNDAY. DRIER AND SLIGHTLY COOLER AIR
ALONG WITH GUSTY NW TO N WINDS WILL FILL IN OVER THE MARINE AREAS
THROUGH THIS TIME. AS A RESULT...A SMALL CRAFT ADVISORY FOR WINDS
AND SEAS WILL REMAIN IN PLACE FROM THIS AFTERNOON THROUGH SUNDAY AND
WILL LIKELY BE EXPANDED OVER THE BIG ISLAND WATERS THIS AFTERNOON
AS THE FRONT BEGINS TO MOVE THROUGH.

ALTHOUGH THE WINDS WILL RELAX MONDAY AND TUESDAY AS A RIDGE OF HIGH
PRESSURE SETS UP OVER THE STATE...A MODERATE TO LARGE NW SWELL WILL
LIKELY RESULT IN THE SMALL CRAFT ADVISORY BEING EXTENDED THROUGH
MONDAY NIGHT. THIS SWELL WILL GENERATE NEAR ADVISORY-LEVEL SURF
ALONG NORTH FACING SHORES THROUGH THIS TIME.

THE LATEST GUIDANCE REMAINS IN DECENT AGREEMENT THROUGH WEDNESDAY
AND THURSDAY AND DEPICTS ANOTHER FRONTAL BOUNDARY WEAKENING AND
STALLING FROM EAST TO WEST NORTH OF THE MARINE AREAS AS A RIDGE OF
HIGH PRESSURE REMAINS IN PLACE ACROSS THE STATE.

THE NEXT LARGE NORTHWEST SWELL IS EXPECTED WEDNESDAY THROUGH
THURSDAY...WHICH WILL LIKELY GENERATE WELL ABOVE WARNING-LEVEL SURF
ALONG THE EXPOSED NORTH AND WEST FACING SHORES. THE LATEST ENSEMBLE
WAVE GUIDANCE SUPPORTS THIS SWELL BUILDING THROUGH THE DAY
WEDNESDAY...PEAKING THROUGH THE WEDNESDAY NIGHT PERIOD AND SLOWLY
EASING THURSDAY THROUGH FRIDAY. HOWEVER...PROVIDED THE CURRENT
ENSEMBLE SPREAD IN THE GUIDANCE THIS FAR OUT IN THE FORECAST...
FURTHER FINE-TUNING WITH REGARD TO THE TIMING AND PEAK WILL REMAIN
POSSIBLE OVER THE COMING DAYS AS THE STRONG LOW PRESSURE
ASSOCIATED WITH THIS SWELL EVOLVES AND LIFTS NORTHEAST TOWARD THE
ALEUTIAN ISLANDS THROUGH THE WEEKEND AND INTO MONDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST SUNDAY FOR OAHU.

WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM HST SUNDAY FOR
NIIHAU-KAUAI.

SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM HST SUNDAY
FOR ALL COASTAL WATERS EXCEPT BIG ISLAND WINDWARD...SOUTHEAST AND
LEEWARD WATERS.

&&

$$

DISCUSSION...JACOBSON
AVIATION...KINEL
MARINE...GIBBS


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