Drought in Hawaii, January 1 to 31, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST FRI DEC 31 2010

.SYNOPSIS...
EXPECT LIGHT AND VARIABLE WINDS WITH LOCAL LAND BREEZES TONIGHT. AS
A RESULT...LOCALLY DENSE SMOKE FROM THE NEW YEARS EVE HOLIDAY
FIREWORKS MAY NOT DISPERSE IN SOME AREAS UNTIL SEVERAL HOURS AFTER
MIDNIGHT. ON NEW YEARS DAY...THE ATMOSPHERE WILL BECOME INCREASINGLY
UNSTABLE AS AN UPPER LEVEL LOW DEVELOPS NEAR THE WESTERN ISLANDS.
THIS WILL PROVIDE A CHANCE FOR THUNDERSTORMS TO DEVELOP FROM LATE
SATURDAY INTO SUNDAY. THE TRADES WILL RETURN LATE SUNDAY AND MONDAY
AS THE UPPER LEVEL LOW DRIFTS SOUTHWEST AWAY FROM THE STATE...AND A
SURFACE RIDGE BUILDS TO OUR NORTH.

&&

.DISCUSSION...
THE LAST VESTIGES OF A SURFACE RIDGE NORTH OF THE STATE,,,WHICH
BROUGHT BACK A BRIEF PERIOD OF TRADE WIND WEATHER...APPEAR TO BE
DISAPPEARING AT DUSK THIS EVENING. SURFACE PRESSURES ARE FALLING
SIGNIFICANTLY ACROSS THE STATE...AND OUR LOW-LEVEL WINDS HAVE BECOME
LIGHT AND VARIABLE AFTER SUNSET TONIGHT. THIS WILL ALLOW LOCAL LAND
BREEZES TO DEVELOP IN MANY LOCATIONS ACROSS THE ISLAND CHAIN.
UNFORTUNATELY...THESE LIGHT WINDS WILL PROBABLY NOT ALLOW ENOUGH
ADVECTION OF SMOKE OUT OF THOSE PARTS OF THE ISLANDS WHERE THE NEW
YEARS EVE HOLIDAY FIREWORKS EXTRAVAGANZA WILL BE MOST PROLIFIC.
THEREFORE...EXPECT SOME AREAS TO HAVE LOCALLY DENSE SMOKE FOR
SEVERAL HOURS AFTER MIDNIGHT.

WEAK RIDGING IN THE MIDDLE AND UPPER LEVELS OF THE ATMOSPHERE OVER
THE ISLANDS IS CURRENTLY CONTRIBUTING TO A RATHER STABLE
ENVIRONMENT. HOWEVER... WATER VAPOR IMAGERY DEPICTS THE AXIS OF A
SHARPENING UPPER TROPOSPHERIC TROUGH ALONG LONGITUDE 166W...OR ABOUT
760 MILES WEST NORTHWEST OF LIHUE. THIS FEATURE IS DIGGING TOWARD
THE EAST SOUTHEAST AT ABOUT 40 MPH.
 THE BIG UPCOMING CHANGE TO THE LOCAL FORECAST THIS HOLIDAY WEEKEND
IS RELATED TO THIS UPPER LEVEL TROUGH...WHICH IS FORECAST TO BE OVER
KAUAI AND OAHU BY DAYBREAK NEW YEARS DAY MORNING. COLD AIR ALOFT AND
DYNAMIC LIFT DUE TO THE PRESENCE OF THIS TROUGH ALOFT WILL WEAKEN
AND RAISE THE SUBSIDENCE INVERSION...AND CAUSE THE AIR MASS OVER THE
STATE TO BECOME INCREASINGLY UNSTABLE. AT THE SAME TIME...A SURFACE
TROUGH...WHICH IS LIKELY A REFLECTION OF THE UPPER LEVEL TROUGH...
IS FORECAST TO DEEPEN WEST OF THE STATE. THIS TROUGH WILL KEEP THE
THE SURFACE WINDS LIGHT THROUGH SATURDAY...CAUSING A WEAK CONVECTIVE
WEATHER PATTERN TO DEVELOP...WITH LOCAL SEA BREEZES AND CLOUD BUILD
UPS AND SHOWERS DURING THE AFTERNOON...MAINLY OVER THE INTERIOR
SECTIONS OF THE ISLANDS.

AN UPPER LEVEL LOW IS FORECAST TO PINCH OFF FROM THE UPPER LEVEL
TROUGH LATE SATURDAY. THIS LOW IS EXPECTED TO MOVE SOUTHWARD NEAR
KAUAI AND OAHU SATURDAY NIGHT AND SUNDAY. EVEN THOUGH THE FORECAST
MODELS DO NOT INDICATE SIGNIFICANT MOISTURE WHILE THIS LOW ALOFT IS
NEARBY...THIS PATTERN ALLOWS A CHANCE FOR THUNDERSTORMS TO DEVELOP.
SUCH DEVELOPMENT COULD LEAD TO LOCALLY HEAVY RAINFALL. HOWEVER...
WITH THE LIMITED MOISTURE SUPPLY...IT DOES NOT APPEAR ANY HEAVY
RAINS THAT OCCUR WILL BE WIDESPREAD.

BY LATE SUNDAY AND MONDAY...A RIDGE ALOFT WILL BUILD EASTWARD NORTH
OF THE ISLANDS...WHICH WILL PUSH THE THE UPPER LEVEL LOW TOWARD THE
SOUTHWEST AWAY FROM KAUAI. AT THE SAME TIME...THE BUILDING UPPER
RIDGE WILL ALLOW SURFACE RIDGING TO DEVELOP TO THE NORTH OF THE
ALOHA STATE. THIS WILL RESULT IN A RETURN OF THE TRADE WINDS TO THE
ISLANDS FROM SUNDAY NIGHT THROUGH WEDNESDAY. WINDS OVER THE SUMMITS
OF THE BIG ISLAND AND ACROSS MOUNT HALEAKALA ON MAUI MAY INCREASE TO
WIND ADVISORY STRENGTH STARTING SUNDAY NIGHT AS THE UPPER RIDGE
INCREASES THE WINDS IN THE LOWER TO MIDDLE TROPOSPHERE.

ANOTHER UPPER TROUGH IS FORECAST TO DIG NORTH OF THE STATE ON
WEDNESDAY...ERODING THE SURFACE HIGH BELOW AND CAUSING THE TRADE
WINDS TO ONCE AGAIN SUBSIDE. THE LIGHT WINDS SHOULD NOT LAST LONG
HOWEVER AS A REINFORCING SURFACE HIGH IS FORECAST TO MOVE NORTH OF
THE ISLANDS...BRINGING BACK THE TRADES ON THURSDAY. THE HIGH MAY
PUSH A FRONT DOWN NEAR...AND POSSIBLY OVER...THE WESTERN ISLANDS
THURSDAY AND FRIDAY. CURRENTLY...THIS FRONT IS NOT FORECAST TO BRING
HEAVY RAINFALL.

&&

.MARINE...
BUOY 51001 SHOWS A WEST NORTHWEST SWELL WITH A SWELL HEIGHT OF 8
FEET AND A PERIOD OF 14 SECONDS. THIS SWELL...WHICH IS FROM AN
AZIMUTH OF APPROXIMATELY 305 DEGREES HAS INCREASED SURF HEIGHTS
ALONG NORTH AND WEST FACING SHORES OF KAUAI. OAHU AND THE ISLANDS OF
MAUI COUNTY APPEAR TO BE PARTIALLY SHELTERED FROM THIS SWELL BY
KAUAI...SO SURF HEIGHTS ARE LIKELY SMALLER THERE. FOR EXAMPLE...THE
WAIMEA BAY BUOY IS CURRENTLY INDICATING A SIGNIFICANT WAVE HEIGHT OF
JUST BELOW 5 FEET. THIS WEST NORTHWEST SWELL IS FORECAST TO
GRADUALLY DIMINISH BY LATE SATURDAY. A MUCH LARGER...LONG PERIOD
WEST NORTHWEST SWELL ARRIVING SATURDAY NIGHT WILL PROBABLY PRODUCE
SURF HEIGHTS NEAR THE HIGH SURF WARNING THRESHOLDS ALONG NORTH AND
WEST FACING SHORES ON SUNDAY. THIS LARGE SWELL WILL ALSO LIKELY
REACH THE LEEWARD BIG ISLAND BY SUNDAY NIGHT...POSSIBLY GENERATING
SURF HEIGHTS NEAR THE WARNING THRESHOLD OF 12 FEET ALONG PARTS OF
THE KONA COAST.

THE WEST NORTHWEST SWELL WILL INCREASE THE COMBINED SEAS NEAR THE
SMALL CRAFT ADVISORY /SCA/ THRESHOLD OF 10 FEET ON SUNDAY AND
MONDAY. ALSO...AS THE TRADES STRENGTHEN LATE SUNDAY...WIND SPEEDS
WILL LIKELY REACH THE SCA THRESHOLD IN THE TYPICALLY WINDY AREAS
ADJACENT TO MAUI AND THE BIG ISLAND STARTING SUNDAY NIGHT. THESE
WINDY CONDITIONS ARE CURRENTLY FORECAST TO CONTINUE AT LEAST
THROUGH TUESDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

HOUSTON