377 
FXHW60 PHFO 171400
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST SUN FEB 17 2013

.SYNOPSIS...
VERY STRONG AND GUSTY TRADE WINDS WILL CONTINUE ACROSS THE MAIN 
HAWAIIAN ISLANDS THROUGH EARLY NEXT WEEK AS HIGH PRESSURE BUILDS FAR 
NORTH OF THE AREA. LOW CLOUDS AND SHOWERS TRANSPORTED BY THE TRADES 
WILL CONTINUE ACROSS WINDWARD AND MAUKA AREAS...WITH THE STRONG 
TRADES CARRYING A FEW SHOWERS OVER TO LEEWARD SECTIONS OF SOME OF 
THE SMALLER ISLANDS. EXPECT A SLIGHTLY WETTER TRADE WIND WEATHER 
PATTERN EARLY NEXT WEEK.

&&

.DISCUSSION...
THE VERY TIGHT PRESSURE GRADIENT SOUTH OF TWIN 1035 MB SURFACE 
HIGHS...ONE NEAR 38N 145W AND ANOTHER NEAR 39N 159W...CONTINUE TO 
PRODUCE STRONG AND GUSTY LOW-LEVEL TRADE WINDS ACROSS THE MAIN 
HAWAIIAN ISLANDS EARLY THIS MORNING. ALOFT...MIDDLE AND UPPER LEVEL 
TROUGH ARE IN THE VICINITY OF THE EASTERN END OF THE ISLAND CHAIN. 
THIS IS CAUSING THE ATMOSPHERE ACROSS THE EASTERN ISLANDS TO BE 
SLIGHTLY UNSTABLE. ALSO...A WEAKENING UPPER-LEVEL RIDGE IS EVIDENT 
NEAR KAUAI AND OAHU. LOW-LEVEL MOISTURE REMAINS RATHER LIMITED OVER 
THE WESTERN ISLANDS...WITH SLIGHTLY GREATER PRECIPITABLE WATER 
VALUES NEAR THE BIG ISLAND.

THE PRESENCE OF THE TROUGHING ALOFT NEAR THE EASTERN ISLANDS IS 
ENHANCING THE LOW CLOUDS AND SHOWERS CARRIED BY THE TRADES. THESE 
SHOWERS ARE MAINLY AFFECTING WINDWARD AND MAUKA AREAS OF THE 
STATE...BUT A FEW OF THE SHOWERS MAY SPREAD TO LEEWARD SECTIONS OF 
THE SMALLER ISLANDS DUE TO THE ROBUST TRADES...ESPECIALLY THIS 
MORNING. 

THE FORECAST MODELS INDICATE STRONG HIGH PRESSURE WILL REMAIN FAR 
NORTH OF THE ISLAND CHAIN THROUGH TONIGHT. THIS WILL KEEP SUSTAINED 
WIND SPEEDS AND/OR PEAK WIND GUSTS NEAR THE WIND ADVISORY CRITERIA 
ACROSS MOST OF THE ALOHA STATE...EXCEPT THE BIG ISLAND SUMMITS...AT 
LEAST THROUGH TONIGHT. SINCE THE MODELS SUGGEST THE HIGH PRESSURE 
MAY BUILD EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE STATE MAY 
BECOME EVEN TIGHTER. IF SO...THIS WOULD RESULT IN THE STRONG GUSTY 
TRADES CONTINUING THROUGH EARLY NEXT WEEK...AND THE WIND ADVISORY 
MAY NEED TO BE CONTINUED FOR PORTIONS OF THE STATE ON MONDAY ALSO.  

MEANWHILE...THE UPPER-LEVEL RIDGE OVER THE WESTERN ISLANDS IS 
EXPECTED TO CONTINUE TO WEAKEN TODAY. AT THE SAME TIME...THE 
RELATIVELY UNSTABLE AIR MASS IS FORECAST TO REMAIN NEAR THE EASTERN 
ISLANDS. THIS WILL ALLOW FOR ENHANCEMENT OF THE LOW CLOUDS AND 
SHOWERS CARRIED BY THE TRADES TO CONTINUE FROM TODAY INTO EARLY 
NEXT WEEK. AS A RESULT...EXPECT LOW CLOUDS AND SHOWERS TO CONTINUE 
FAVORING WINDWARD AND MAUKA AREAS. THE STRONG TRADES WILL ALSO 
CONTINUE TO CARRY SOME OF THESE SHOWERS OVER TO LEEWARD AREAS OF THE 
SMALLER ISLANDS...ESPECIALLY NIGHTS AND MORNINGS. 

LOOKING BEYOND MID-WEEK...THE MODELS SUGGEST A TRADE WIND WEATHER 
PATTERN WILL CONTINUE THROUGH THE END OF THE NEW WORK WEEK. THE 
FORECAST GUIDANCE SUGGESTS THE TRADES WILL REMAIN STRONG AND GUSTY 
ALSO. IN ADDITION...THE RELATIVELY WET TRADE WIND WEATHER PATTERN 
MAY CONTINUE ACROSS MOST WINDWARD AND MAUKA AREAS OF THE STATE. IF 
SO...LEEWARD AREAS OF THE SMALLER ISLANDS MIGHT CONTINUE TO RECEIVE 
BRIEF PASSING SHOWERS CARRIED OVER BY THE STRONG TRADES.

&&

.MARINE...
A GALE WARNING REMAINS IN EFFECT FOR THE WINDIER WATERS ADJACENT TO 
THE ISLANDS OF MAUI COUNTY AND THE BIG ISLAND DUE TO THE LOCALIZED 
AFFECTS THE ISLAND TERRAIN HAS IN ACCELERATING THE ALREADY STRONG 
LOW-LEVEL TRADE WIND FLOW. A SMALL CRAFT ADVISORY /SCA/ ALSO REMAINS 
IN EFFECT FOR THE REMAINING HAWAIIAN WATERS DUE TO THE COMBINATION 
OF THESE STRONG TRADE WINDS...INCREASED SHORT-PERIOD TRADE WIND 
GENERATED WAVES AND A LONG-PERIOD NORTHWEST SWELL. THE GALE WARNING 
AND SCA ARE IN EFFECT THROUGH WEDNESDAY. 

THE NEW WEST NORTHWEST SWELL ARRIVED AT NATIONAL DATA BUOY CENTER 
BUOY 51101...WHICH IS LOCATED NORTHWEST OF KAUAI. HOWEVER...BASED ON 
THE WAVE WATCH III MODEL GUIDANCE...THE SWELL HEIGHT APPEARS TO BE 
ABOUT 2 FEET BELOW THE GUIDANCE. WE EXPECT THIS SWELL WILL CONTINUE 
TO BUILD THIS MORNING BEFORE PEAKING LATER TODAY. THE SURF PRODUCED 
BY THIS SWELL IS EXPECTED TO REACH HEIGHTS ABOVE THE HIGH SURF 
ADVISORY THRESHOLDS ALONG MOST NORTH AND WEST FACING SHORES OF THE 
SMALLER ISLANDS...BEFORE SLOWLY SUBSIDING FROM LATE TONIGHT THROUGH 
MONDAY. THEREFORE...A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH 
MONDAY AFTERNOON FOR EXPOSED NORTH AND WEST FACING SHORES OF THE 
SMALLER ISLANDS DUE TO THIS SWELL. A HIGH SURF ADVISORY IS ALSO IN 
EFFECT STARTING LATER THIS MORNING AND CONTINUING THROUGH TONIGHT 
FOR WEST FACING SHORES OF THE BIG ISLAND. OTHERWISE...ONLY A MODEST 
NORTHWEST SWELL IS EXPECTED FROM LATE WEDNESDAY NIGHT INTO FRIDAY.

ELSEWHERE...THE STRONG TRADE WINDS HAVE GENERATED ELEVATED CHOPPY 
SURF ALONG EAST FACING SHORES. AS A RESULT...A HIGH SURF ADVISORY 
REMAINS IN EFFECT THROUGH WEDNESDAY AFTERNOON FOR EAST FACING SHORES 
OF MOST ISLANDS. THIS HIGH SURF ADVISORY WILL LIKELY BE EXTENDED 
BEYOND WEDNESDAY DUE TO THE STRONG TRADES...WHICH ARE EXPECTED TO 
CONTINUE NEXT WEEK.

&&

.AVIATION...
STRENGTHENING TRADE WINDS CONTINUE AIRMET TANGO FOR TEMPO MODERATE 
ISOL SEVERE LOW LEVEL TURBULENCE DOWNWIND OF MOUNTAINS ON ALL 
ISLANDS. SUSTAINED SURFACE WINDS HAVE BEEN BETWEEN 25 AND 30 KT 
OVERNIGHT. WITH WINDS EXPECTED TO INCREASE AGAIN DURING THE DAY 
TODAY...AN AIRMET WILL LIKELY BE NEEDED FOR SURFACE WINDS. STRONG 
WINDS WILL CONTINUE FOR THE NEXT SEVERAL DAYS.

OVERALL VFR CONDITIONS ARE EXPECTED WITH BRIEF MVFR CIGS AND VIS
POSSIBLE FOR WINDWARD AREAS DUE TO CLOUDS AND SHOWERS BEING CARRIED 
IN ON THE TRADES. 

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY THROUGH 600 AM HST MONDAY FOR THE ENTIRE STATE OF 
HAWAII...EXCEPT THE BIG ISLAND SUMMITS.

HIGH SURF ADVISORY THROUGH 600 PM HST WEDNESDAY FOR EAST FACING 
SHORES OF KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND. 

HIGH SURF ADVISORY THROUGH 600 PM HST MONDAY FOR NORTH AND WEST 
FACING SHORES OF NIIHAU...KAUAI...OAHU AND MOLOKAI...AND FOR NORTH 
FACING SHORES OF MAUI. 

HIGH SURF ADVISORY FROM 600 AM THIS MORNING THROUGH 600 AM HST 
MONDAY FOR WEST FACING SHORES OF THE BIG ISLAND.

GALE WARNING UNTIL 600 PM HST WEDNESDAY FOR MAALAEA BAY...THE WATERS 
SOUTH OF THE BIG ISLAND...AND THE PAILOLO AND ALENUIHAHA CHANNELS. 

SMALL CRAFT ADVISORY UNTIL 600 PM HST WEDNESDAY FOR ALL REMAINING 
HAWAIIAN WATERS.

&&

$$

DISCUSSION/MARINE...HOUSTON
AVIATION...M BALLARD