HAMweather.com Area Forecast Discussion for County Warning Area HFO

Thu, 16 Feb 2012 12:39:01 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
831 PM HST WED FEB 15 2012

.SYNOPSIS...
HIGH PRESSURE FAR NORTHEAST OF THE STATE WILL STRENGTHEN THROUGH
FRIDAY AND TRADE WINDS WILL INCREASE AS A RESULT. RIDGING ALOFT
WILL KEEP THE ATMOSPHERE STABLE THROUGH FRIDAY. ANY SHOWERS THAT
DO OCCUR OVER THE NEXT COUPLE DAYS WILL BE LIGHT GIVEN THE
EXPECTED STABLE AND GENERALLY DRY ATMOSPHERE...AND WILL BE FOCUSED
ACROSS WINDWARD SLOPES. THE SHOWERS MAY BECOME MORE ACTIVE FRIDAY
NIGHT THROUGH THIS WEEKEND AS A LOW ALOFT MOVES OVER THE STATE.

.DISCUSSION...
A SURFACE HIGH IS LOCATED FAR NORTHEAST OF THE AREA NEAR 32N138W
WHICH IS DRIVING MODERATE TRADE WINDS TONIGHT. THIS HIGH IS EXPECTED
TO STRENGTHEN...AND OUR TRADE WINDS INCREASE AS A RESULT...REACHING
FRESH TO STRONG BREEZES BY FRIDAY. A DRY AND STABLE ATMOSPHERE IS PRESENT
ALOFT DUE TO AN UPPER LEVEL RIDGE OVER THE STATE...KEEPING SHOWERS
AND CLOUD COVER TO A MINIMUM. HIGH CLOUDS FROM A STATIONARY FRONT
NORTHWEST OF THE STATE ARE OCCASIONALLY PASSING OVER THE WESTERN
HALF OF THE STATE.

WINDS AT THE MIDLEVELS HAVE ALREADY JUMPED UP RESULTING IN STRONG
WINDS AROUND THE HALEAKALA SUMMIT EARLIER TODAY...AND A WIND
ADVISORY IS IN EFFECT FOR TONIGHT. MODELS SHOW WINDS CARRYING ON
FOR AN EXTENDED PERIOD OF TIME...BUT WILL MONITOR OBSERVATIONS AND
MAKE A CALL WITH THE MORNING FORECAST PACKAGE.

THE BUILDING TRADE WINDS WILL ALSO PROVIDE MORE WINDWARD SHOWERS
LIKELY BEGINNING BY TOMORROW. RAINFALL WILL BE MODERATE THURSDAY
THROUGH FRIDAY BUT SHOWERS WILL BECOME MORE ACTIVE FRIDAY EVENING AS
A LOW ALOFT APPROACHES FROM THE SOUTHEAST. THIS PERIOD OF ACTIVE
TRADE WIND SHOWERS WILL CONTINUE THROUGH THIS WEEKEND. WINDWARD
SLOPES WILL BE THE FOCUS...BUT ELEVATED WINDS WILL CARRY SHOWERS
TO LEEWARD SIDES OF THE SMALLER ISLANDS OCCASIONALLY. RAINFALL
SHOULD BE MOST ACTIVE AROUND THE BIG ISLAND SINCE IT WILL BE
CLOSEST TO THE LOW. MOISTURE NEAR THE BIG ISLAND MAY GET DEEP
ENOUGH TO BRING PRECIPITATION TO THE BIG ISLAND SUMMITS AND
TEMPERATURES ARE LIKELY TO BE COLD ENOUGH FOR SNOW OR ICE.

BY EARLY NEXT WEEK THERE ARE SOME HINTS THAT THE SURFACE RIDGE
WILL SHIFT SLIGHTLY TO THE EAST ALLOWING FOR A MORE SOUTHEAST
SHIFT IN THE TRADES. IN THE UPPER-LEVELS...THE LOW WILL LINGER IN
THE VICINITY OF HAWAII.

.AVIATION...
VFR CONDITIONS WILL PREVAIL OVER THE AREA THROUGH TOMORROW. ISOL 
MVFR CIGS WILL BE CONFINED TO MAUKA AREAS. NO AIRMETS ARE IN 
EFFECT...BUT A STRENGTHENING TRADE WIND FLOW ON THURSDAY MAY 
REQUIRE AN AIRMET TANGO SERIES FOR LOW LEVEL TURB.

.MARINE...
A LARGE NORTHWEST SWELL WILL CONTINUE TO BUILD INTO TOMORROW. A
HIGH SURF ADVISORY IS IN EFFECT FOR NORTH AND WEST SHORES OF NIIHAU
KAUAI OAHU AND NORTH SHORES OF MOLOKAI AND MAUI. ENOUGH WEST
COMPONENT IS PRESENT IN THE SWELL TO GENERATE ADVISORY LEVEL SURF
FOR WEST FACING SHORES OF THE BIG ISLAND AND IT WILL TOO GO ABOVE
ADVISORY LEVELS AFTER MIDNIGHT. THIS SWELL IS EXPECTED TO BE A
HIGH END ADVISORY LEVEL SURF EVENT.

STRENGTHENING TRADE WINDS THURSDAY COULD ALSO PLAY A FACTOR OVER 
THE NEXT FEW DAYS. ROUGH WIND DRIVEN WAVES ALONG EAST FACING SHORES 
COULD ALSO PRODUCE HIGH SURF LEVELS THERE AS WELL.

A SMALL CRAFT ADVISORY /SCA/ REMAINS IN EFFECT AND HAS BEEN
EXTENDED THROUGH FRIDAY FOR ALL HAWAIIAN COASTAL WATERS EXCEPT
MAALAEA BAY DUE TO THE INCOMING SWELL AND INCREASING TRADES. MAALAEA
BAY WILL LIKELY BE ADDED TOMORROW AS THE TRADES STRENGTHEN.

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY THROUGH 6 PM FRIDAY FOR NORTH AND WEST SHORES
OF NIIHAU KAUAI OAHU AND NORTH SHORES OF MOLOKAI AND MAUI.

HIGH SURF ADVISORY FROM MIDNIGHT TONIGHT THROUGH 6 PM FRIDAY FOR
WEST FACING SHORES OF THE BIG ISLAND.

WIND ADVISORY UNTIL 4 AM HST THURSDAY FOR HALEAKALA SUMMIT.

SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR ALL HAWAIIAN WATERS
EXCEPT MAALAEA BAY-