Drought in Hawaii, December 1 to 31, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
845 PM HST WED NOV 30 2011

.SYNOPSIS...
NORTHEAST WINDS WILL INCREASE NEAR KAUAI AND OAHU THROUGH
THURSDAY...WHILE LIGHTER TRADE WINDS WILL CONTINUE OVER MAUI COUNTY
AND THE BIG ISLAND. PASSING SHOWERS WILL FOCUS OVER WINDWARD AND
MAUKA AREAS STATEWIDE...BUT WILL BE MORE FREQUENT OVER KAUAI AND
OAHU THROUGH THURSDAY...AS A WEAK FRONT STALLS AND DISSIPATES
NEARBY. LIGHT TO MODERATE TRADE WINDS ON FRIDAY WILL TURN TO THE
SOUTHEAST OVER THE WEEKEND...AS ANOTHER FRONT APPROACHES FROM THE
NORTHWEST.

&&

.DISCUSSION...
CURRENTLY...LOW LEVEL WINDS OVER THE ISLANDS ARE UNDER THE INFLUENCE
OF TWO SEPARATE HIGH PRESSURE SYSTEMS...ONE FAR TO THE NW AND THE
OTHER FAR TO THE NE. A SHARP N-S ORIENTED SURFACE TROUGH HAS
DEVELOPED BETWEEN THESE TWO HIGHS...AND IS OVER WATERS NE OF MAUI
AND THE BIG ISLAND. LOW LEVEL CONVERGENCE ALONG THE SURFACE TROUGH
IS BEING ENHANCED BY A PASSING TROUGH ALOFT...RESULTING IN SCATTERED
THUNDERSTORMS ABOUT 200 TO 600 MILES NE OF MAUI AND THE BIG ISLAND.

THE INCREASING NNE WINDS NEAR KAUAI AND OAHU WILL BRING BRIEF
PASSING SHOWERS TO WINDWARD AND N SHORE COMMUNITIES THROUGH
THURSDAY AS THE HIGH TO THE NW PUSHES A WEAKENING SHEAR LINE OVER
THESE ISLANDS...WITH THE SHEAR LINE DISSIPATING NEAR KAUAI AND OAHU
ON FRIDAY. MEANWHILE...A SOMEWHAT DRIER...AND LIGHTER WIND...REGIME
WILL PREVAIL OVER MAUI COUNTY AND THE BIG ISLAND.

AS THE SURFACE TROUGH TO THE NE GRADUALLY DISSIPATES AND DRIFTS W
OVER THE NEXT 2 DAYS...THE HIGH TO THE NW WILL MOVE E AND WEAKEN.
END RESULT WILL BE A TREND TOWARD TYPICAL ENE TRADE WINDS ON
FRIDAY...WITH SHOWERS FOCUSING OVER WINDWARD AND MAUKA AREAS. WINDS
WILL TURN TO THE SE ON SATURDAY...AND WEATHER WILL BE MOSTLY DRY
AROUND THE STATE...AS HIGH PRESSURE BECOMES ESTABLISHED FAR NE OF
THE ISLANDS...AND ITS ASSOCIATED RIDGE IS SHUNTED S TOWARD THE
ISLANDS...IN ADVANCE OF AN APPROACHING FRONT.

THE FRONT WILL APPROACH KAUAI LATE THIS WEEKEND...WHICH REPRESENTS
A RATHER DRAMATIC SHIFT FROM MODEL RUNS SEEN YESTERDAY. RECENT 00Z
GFS AND 12Z ECMWF SOLUTIONS ARE SIGNIFICANTLY DIFFERENT AS WE
APPROACH THE BEGINNING OF NEXT WEEK WITH RESPECT TO THE FRONT AND
ITS EVENTUAL MOTION AND STRENGTH...THUS THE FORECAST CONTAINS A
SIGNIFICANT AMOUNT OF UNCERTAINTY FROM SUNDAY ONWARD. WILL LIKELY BE
TWEAKING THE FORECAST FOR THIS TIME PERIOD OVERNIGHT...PENDING THE
ARRIVAL OF THE LATEST 00Z ECMWF GUIDANCE.

&&

.MARINE...
A NEW LONG PERIOD NNW SWELL IS BUILDING AT BUOY 51101 TO THE NW OF
KAUAI THIS EVENING...AND LATEST OBS SUPPORT SURF REACHING ADVISORY
LEVELS LATER TONIGHT...WITH A HIGH SURF ADVISORY GOING INTO EFFECT
FOR EXPOSED N AND W SHORES AT MIDNIGHT TONIGHT. THE BUILDING SWELL
WILL COMBINE WITH INCREASING NNE WINDS TO DRIVE SEAS ABOVE 10
FEET...STARTING LATER TONIGHT IN WATERS SURROUNDING KAUAI AND N OF
OAHU...AND THE EXISTING SMALL CRAFT ADVISORY /SCA/ HAS BEEN MODIFIED
TO GO INTO EFFECT WITH THE NEXT COASTAL WATERS ISSUANCE AT 10 PM
TONIGHT. COMBINED SEAS OF 10 FEET OR MORE SPREADING TO ADDITIONAL
MARINES ZONES WILL LIKELY REQUIRE AN EXPANSION OF THE SCA TO
ADDITIONAL ZONES.

&&

.AVIATION...
KAUAI IN THE PATH OF SOME PREVAILING BKN LOW CLOUDS WITH CEILINGS
IN THE VFR RANGE. SCT SHRA MOVG THROUGH THE COUNTY CONTAINS BRIEF
MVFR CEILINGS AND VIS.

SAT IMAGERY ALSO SHOW PATCHY BKN LOW CLOUDS SCT THROUGHOUT THE REST
OF THE MAIN HAWAIIAN ISLANDS. THEY ALSO CONTAIN BRIEF MVFR CEILINGS
AND/OR VIS. THESE CLDS AND SHRA WL FAVOR THE WINDWARD AND MT AREAS.
ON THE BIG ISLAND...BROKEN LO CLOUDS CONTINUE TO HUG THE CSTL AREAS
OF KONA S OF PHKO. BASES OF THESE CLOUDS ARE IN THE VFR RANGE AS
WELL...BUT ALSO CONTAIN BRIEF MVFR CEILINGS. LOOK FOR THEM TO LINGER
INTO THE EARLY A.M. HOURS OF FRIDAY BEFORE DISSIPATING.

NNE LO LVL WINDS ACRS KAUAI COUNTY ARE MARGINALLY STRONG. WL KEEP AN
EYE ON IT...AN AIRMET FOR TURB MAY BE NEEDED FOR BLOW 090 BY
01/1000 UTC.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM HST FRIDAY FOR
NORTH AND WEST FACING SHORES OF KAUAI NIIHAU AND OAHU AND FOR NORTH
FACING SHORES OF MOLOKAI AND MAUI.

SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-OAHU
WINDWARD WATERS.

&&

DISCUSSION/MARINE...BIRCHARD
AVIATION...LAU