FXHW60 PHFO 110633
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST FRI FEB 10 2012

.SYNOPSIS...
FRESH TO LOCALLY STRONG TRADE WINDS WILL TRANSPORT LOW CLOUDS AND 
TRADE SHOWERS MAINLY TO WINDWARD FACING SLOPES OF THE HAWAIIAN 
ISLANDS THIS WEEKEND. OUR WINDS WILL GRADUALLY WEAKEN AND SHIFT TO A 
SOUTHEASTERLY DIRECTION WITH LOCAL AFTERNOON SEA BREEZES AND NIGHT 
TIME LAND BREEZES STARTING EARLY NEXT WEEK ON THE SMALLER ISLANDS. 
THE SOUTHEAST FLOW WILL ALSO TRANSPORT PATCHY VOLCANIC HAZE OVER THE 
SMALLER ISLANDS TUESDAY AND WEDNESDAY...BEFORE THE TRADES RETURN 
NEXT THURSDAY.

&&

.DISCUSSION...
A SURFACE RIDGE EXTENDS WEST FROM A 1029 MB SURFACE HIGH NEAR 28N 
148W TO A POINT ABOUT 345 MILES NORTH OF LIHUE. THE PRESSURE 
GRADIENT SOUTH OF THIS RIDGE WAS MAINTAINING THE LOW-LEVEL TRADE 
WIND FLOW ACROSS THE ALOHA STATE EARLY THIS EVENING. AN UPPER 
TROPOSPHERIC LOW OVER THE BIG ISLAND WAS EVIDENT IN WATER VAPOR 
IMAGERY AND SATELLITE DERIVED UPPER LEVEL WINDS. HOWEVER...MOISTURE 
IN THE LOWER ATMOSPHERE REMAINS WELL BELOW NORMAL...SO LOW CLOUDS 
AND SHOWERS CONTINUE TO BE LIMITED ACROSS MOST AREAS OF THE STATE AT 
DUSK THIS EVENING.

THE AFTERNOON BALLOON SOUNDINGS FROM LIHUE AND HILO...AS WELL AS 
SATELLITE DERIVED PRECIPITABLE WATER VALUES CONFIRM THE PRESENCE OF 
THE DRY AIR SURROUNDING THE ISLANDS. HOWEVER...WITH THE UPPER LEVEL 
LOW NEAR THE BIG ISLAND...LOW CLOUDS AND TRADE SHOWERS ARE POSSIBLE 
THIS EVENING ALONG WINDWARD MAUI AND THE BIG ISLAND. SOME TRADE 
SHOWERS MAY ALSO AFFECT WINDWARD FACING SLOPES OF SOME OF THE OTHER 
SMALL ISLANDS...BUT THESE WILL LIKELY BE BRIEF AND RATHER RATHER 
LIGHT.

AS THE SURFACE HIGH PRESSURE GRADUALLY BUILDS NORTH OF THE ISLANDS 
FROM THROUGH SATURDAY...THE TRADES WILL STRENGTHEN TO FRESH TO 
LOCALLY STRONG SPEEDS THIS WEEKEND. THE UPPER LEVEL LOW WILL LINGER 
NEAR THE BIG ISLAND...BEFORE IT WEAKENS AND DRIFTS SOUTH OF THE AREA 
BY MONDAY. THE TRADES WILL CONTINUE TO FOCUS LOW CLOUDS AND TRADE 
SHOWERS PRIMARILY ALONG WINDWARD FACING TERRAIN...ESPECIALLY 
WINDWARD MAUI AND THE BIG ISLAND...THROUGH MONDAY. 

THE FORECAST MODELS DEPICT A NEW SURFACE FRONT APPROACHING THE AREA 
FROM THE NORTHWEST EARLY NEXT WEEK. THIS WILL CAUSE THE SURFACE 
RIDGE NORTH OF THE ISLANDS TO WEAKEN...WHICH WILL RELAX THE PRESSURE 
GRADIENT. THIS WILL CAUSE THE TRADE WINDS TO EASE AND VEER OUT OF 
THE SOUTHEAST DURING THE FIRST HALF OF NEXT WEEK AS A COLD FRONT 
NEARS THE AREA. THE COLD FRONT IS FORECAST BY THE GFS AND ECMWF 
MODELS TO STALL AND WEAKEN LESS THAN 250 MILES NORTH NORTHWEST OF 
KAUAI WEDNESDAY NIGHT.

THE LIGHT SOUTHEASTERLY FLOW WILL ALLOW THE DEVELOPMENT OF LOCAL 
AFTERNOON SEA AND NIGHT TIME LAND BREEZES...ESPECIALLY TUESDAY AND 
WEDNESDAY ON THE SMALLER ISLANDS. THE LOW-LEVEL SOUTHEASTERLY FLOW 
WILL ALSO LIKELY TRANSPORT PATCHY VOLCANIC HAZE FROM SOURCES ON THE 
BIG ISLAND TO MOST OF THE SMALLER ISLANDS DURING THE MIDDLE OF NEXT 
WEEK. AT THE SAME TIME...THE MODELS SUGGEST WINDWARD MAUI AND THE 
BIG ISLAND WILL CONTINUE TO HAVE SOME CLOUDS AND SHOWERS DURING THIS 
PERIOD.

THE FORECAST MODELS INDICATE THAT HIGH PRESSURE WILL STRENGTHEN 
NORTH OF THE STATE NEXT FRIDAY AS THE FRONT WEAKENS. THIS WILL CAUSE 
THE TRADES TO RETURN FROM THURSDAY THROUGH THE REMAINDER OF THE 
FORECAST PERIOD. THE MODELS ALSO SUGGEST THIS WILL ALSO BE A 
RELATIVELY WET TRADE WIND REGIME...WITH THE STRONG TRADES LIKELY 
TRANSPORTING SOME OF THE SHOWERS OVER TO LEEWARD SECTIONS OF THE 
ISLANDS.

&&

.AVIATION...
SURFACE OBSERVATIONS AND ACARS SOUNDINGS SHOW LOW-LEVEL WINDS UP TO 
25-30 KT ACROSS MAUI COUNTY...AND WE HAVE RECEIVED ONE PIREP OF 
MODERATE LOW-LEVEL TURBULENCE NEAR KAHULUI. WINDS OVER KAUAI AND 
OAHU ARE LIGHTER /15-20KT/ BASED ON ACARS SOUNDINGS FROM 
LIHUE/HONOLULU AND VAD WIND PROFILES FROM THE KAUAI/MOLOKAI RADARS. 
HOWEVER...THE 18Z NAM AND 12Z HIGH RESOLUTION WRF RUNS SHOW A SURGE 
IN WINDS SPREADING WESTWARD OVER THE STATE TONIGHT. WITH THE LIGHTER 
WINDS ACROSS THE WESTERN ISLANDS EXPECTED TO INCREASE...WE WILL KEEP 
THE AIRMET IN EFFECT FOR THE ENTIRE STATE. THESE WINDS /AND THE 
ACCOMPANYING POTENTIAL FOR LOW-LEVEL TURBULENCE/ ARE EXPECTED TO 
CONTINUE THIS WEEKEND...BEFORE STARTING TO WEAKEN AS THEY TURN 
SOUTHEASTERLY EARLY NEXT WEEK. 

TRADE WINDS WILL KEEP CLOUDS AND SHOWERS FOCUSED ACROSS WINDWARD 
SECTIONS OF THE ISLANDS...BUT A RELATIVELY DRY AND STABLE AIRMASS 
WILL KEEP CONDITIONS PREDOMINATELY VFR. AN AREA OF MOISTURE 
ENHANCING WINDWARD CLOUDS OVER THE BIG ISLAND AND MAUI COUNTY WILL 
SPREAD WESTWARD ACROSS OAHU AND KAUAI TONIGHT. VARIABLE BROKEN CLOUD 
CEILINGS CAN BE EXPECTED...WITH THE BULK OF THIS MOISTURE LIMITED TO 
THE LAYER BETWEEN 040 AND 070. HOWEVER...SHOWERS MAY BRING BRIEF 
PERIODS OF MVFR CEILINGS TO WINDWARD SECTIONS.

&&

.MARINE...
THE CURRENT NORTHWEST SWELL CONTINUES TO SUBSIDE EARLY THIS EVENING. 
THE LATEST OBSERVATIONS FROM THE WAIMEA BAY BUOY INDICATE THE 
SIGNIFICANT WAVE HEIGHT IS AROUND 7 FEET WITH A PERIOD OF ABOUT 12 
SECONDS FROM AN AZIMUTH OF 340 DEGREES. THIS SWELL COMBINED WITH 
TRADE WIND GENERATED WAVES CONTINUES TO PRODUCE ELEVATED SEAS OVER 
MOST OF THE HAWAIIAN COASTAL WATERS. IN ADDITION TO THESE LARGE 
SEAS...THE STRENGTHENING TRADES ARE BEING ACCELERATED IN THE 
TYPICALLY WINDY CHANNELS AND WATERS ADJACENT TO THE ISLANDS OF MAUI 
COUNTY AND THE BIG ISLAND. AS A RESULT...A SMALL CRAFT ADVISORY 
/SCA/ IS IN EFFECT FOR ALL HAWAIIAN WATERS TONIGHT. THE SCA HAS BEEN 
EXTENDED THROUGH SUNDAY AFTERNOON.

THE CIRCULATIONS AROUND A SERIES OF LOW PRESSURE SYSTEMS IN THE 
NORTHWEST PACIFIC WITH STRONG WINDS AIMED TOWARD THE HAWAIIAN 
ISLANDS WILL GENERATE ELEVATED SURF ALONG EXPOSED NORTH AND WEST 
FACING BEACHES FROM SUNDAY THROUGH MOST OF THE NEW WORK WEEK. THE 
FIRST NEW NORTHWEST SWELL ARRIVING EARLY SUNDAY MORNING IS EXPECTED 
TO BOOST SURF HEIGHTS TO NEAR THE HIGH SURF ADVISORY CRITERIA ALONG 
NORTH AND SOME WEST FACING SHORES OF MOST OF THE SMALLER HAWAIIAN 
ISLANDS STARTING SUNDAY. THE WAVE WATCH III MODEL SUGGESTS THESE 
ELEVATED SURF CONDITIONS WILL CONTINUE TO PRODUCE SURF AT OR ABOVE 
THE HIGH SURF ADVISORY THRESHOLDS ALONG THESE NORTH AND WEST FACING 
SHORES FROM SUNDAY THROUGH NEXT FRIDAY. 

SURF HEIGHTS ALONG THE WEST FACING SHORES OF THE BIG ISLAND WILL 
LIKELY REMAIN BELOW THE HIGH SURF ADVISORY THRESHOLD THROUGH NEXT 
WEDNESDAY. HOWEVER...A LARGER WEST NORTHWEST SWELL ARRIVING 
WEDNESDAY NIGHT MAY BOOST SURF HEIGHTS TO THE HIGH SURF ADVISORY 
CRITERIA ALONG PORTIONS OF THE KONA COAST NEXT THURSDAY AND FRIDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 600 PM HST SUNDAY FOR ALL HAWAIIAN WATERS.

&&

$$
DISCUSSION/MARINE...HOUSTON
AVIATION...BRAVENDER