Drought in Hawaii, December 1 to 4, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST FRI NOV 30 2007

.SYNOPSIS...
A STALLED COLD FRONT WILL WEAKEN NORTH OF THE ISLANDS TONIGHT...
BRINGING SCATTERED SHOWERS MAINLY TO KAUAI AND OAHU. SOUTHWEST WINDS
WILL INCREASE ON SATURDAY AND SUNDAY AHEAD OF A STRONGER COLD FRONT.
THIS FRONT WILL MOVE ACROSS KAUAI AND OAHU ON SUNDAY BEFORE STALLING
OVER MAUI COUNTY ON SUNDAY NIGHT AND MONDAY.

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS A SHARP UPPER TROUGH 800 MILES NORTH
NORTHEAST OF HONOLULU...WITH THE NEXT SHORTWAVE OF INTEREST 1500
MILES NORTHWEST OF HONOLULU. THE SURFACE FRONT NORTH OF KAUAI WILL
STALL AND WEAKEN AS THE MID-LEVEL FLOW BECOMES PARALLEL TO THE
BOUNDARY. IR SATELLITE SHOWS THE LEADING EDGE OF THE FRONTAL CLOUD
BAND IS JUST IMPINGING ON KAUAI...WITH A PREFRONTAL CONVERGENCE BAND
LINED UP OVER OAHU. REGIONAL RADARS SHOW RELATIVELY LIGHT
REFLECTIVITIES IN THE BAND ACROSS OAHU...BUT WITH MORE SCATTERED
LIGHT TO MODERATE RETURNS NORTHWEST OF KAUAI. 12Z PHLI SOUNDING
SHOWS A WEAK MID-LEVEL WARMING TREND OVER THE PAST 24 HOURS...
HOWEVER THERE IS STILL OVER 900 J/KG OF CAPE IN AN UNMODIFIED
SOUNDING. 04Z POES AMSU PASS SHOWS THE AXIS OF HIGH PRECIPITABLE
WATER IS NOW EDGING SOUTHEASTWARD ACROSS THE STATE. EVEN THOUGH THE
MAIN CONVERGENCE REMAINS ALONG THE FRONT NORTHWEST OF KAUAI...THERE
IS ENOUGH MOISTURE AND INSTABILITY FOR AT LEAST SCATTERED SHOWERS
ACROSS THE SMALLER ISLANDS TONIGHT. THE SURFACE RIDGE OVER THE BIG
ISLAND WILL WEAKEN AND MOVE SOUTHEASTWARD. HOWEVER LAND BREEZES
SHOULD AGAIN DOMINATE ACROSS THE BIG ISLAND...WITH JUST SOME PASSING
MID AND HIGH LEVEL CLOUDS.

THE FIRST SHORTWAVE IS ALREADY WORKING TO BREAK DOWN THE RIDGE NEAR
140W...SETTING UP A FAST ZONAL FLOW ACROSS THE NORTH PACIFIC. THE
NEXT SHORTWAVE IS ASSOCIATED WITH A +175KT UPPER LEVEL JET PER GOES
SATELLITE DERIVED WINDS...AND IS POISED TO CARVE OUT A BROAD TROUGH
ACROSS THE CENTRAL PACIFIC BY EARLY NEXT WEEK. THIS WILL PROPEL A
STRONGER FRONT DOWN ACROSS THE ISLANDS SUNDAY/MONDAY. SOUTHWESTERLY
FLOW WILL INCREASE SATURDAY/SATURDAY NIGHT AHEAD OF THE FRONT. WITH
THE MOIST AIRMASS ALREADY IN PLACE...THE KONA WINDS WILL FAVOR
HIGHER POPS ACROSS TYPICAL LEEWARD AREAS. THE 00Z GFS ACTUALLY HAS
MORE OF A PUSH AND SHOWS THE FRONT MAKING IT TO ALENUIHAHA BEFORE
STALLING SUNDAY NIGHT. THIS IS PRETTY CLOSE TO THE 12Z/30 ECMWF
SOLUTION AS WELL. THE CURRENT FORECAST HAS CATEGORICAL POPS
SUNDAY/SUNDAY NIGHT SPREADING SOUTHWARD ACROSS THE SMALLER
ISLANDS...WHICH LOOKS PRETTY GOOD. MAY NEED TO ADD THUNDER ALONG THE
FRONT AS MID-LEVEL TEMPERATURES START TO FALL. HOWEVER...THE MAIN
THERMAL TROUGH LAGS THE STRONGER DYNAMICS/MOISTURE ALONG THE
BOUNDARY.

THE FORECAST BECOMES MORE PROBLEMATIC BY THE MIDDLE OF NEXT WEEK.
THE CURRENT FORECAST IS GEARED TOWARD THE 12Z/29 GFS...WHICH WAS
VERY PROGRESSIVE. IT BROUGHT A STRONG COLD FRONT ACROSS THE STATE
MID-WEEK...FOLLOWED BY HIGH PRESSURE AND MUCH DRIER AIR
/PRECIPITABLE WATERS NEAR 0.6 INCHES/. THE 00Z/30 GFS TRENDED TOWARD
A MUCH WETTER SOLUTION SIMILAR TO THE ECMWF...AND THE 00Z GFS
ENSEMBLE MEMBERS FOLLOWED SUIT WITH THE OPERATIONAL RUN. THE PAST
FEW ECMWF RUNS HAVE CUT OFF AN UPPER LOW IN THE VICINITY OF THE
STATE...WITH THE 12Z/30 RUN OVER AND SOUTHWEST OF THE STATE...
SIMILAR TO THE 00Z GFS. THIS LEADS TO SURFACE CYCLOGENESIS ALONG THE
STALLED FRONTAL BOUNDARY...WITH THE SOUTHERLY FLOW TAPPING INTO
TROPICAL MOISTURE AGAIN. THE GFS HAS BEEN BACK AND FORTH WITH THIS
SYSTEM...AND THE ECMWF HAS NOT BEEN ALL THAT STABLE EITHER. STILL
NEED TO HASH OUT THE DETAILS...BUT WE MAY NEED TO TREND TOWARD A
WETTER FORECAST AT THE THE END OF THE PERIOD.

&&

.MARINE...
THE NEXT NORTHWEST HAS ARRIVED ABOUT BUOY 51001...WITH A SURGE OF
ENERGY IN THE 15-17 SECOND BAND OVER THE PAST TWO HOURS. WAVEWATCH
III SHOWS THE SWELL CONTINUING TO BUILD OVERNIGHT...AND PEAKING ON
SATURDAY. A HIGH SURF WARNING IS IN EFFECT FOR NORTH AND WEST FACING
SHORES OF NIIHAU...KAUAI...AND OAHU...WITH A HIGH SURF ADVISORY FOR
NORTH AND WEST SHORES OF MOLOKAI AND NORTH SHORES OF MAUI. IT
APPEARS THAT ENOUGH ENERGY FROM THE LARGE SWELL WILL WRAP AROUND THE
SMALL ISLANDS TO WARRANT A HIGH SURF ADVISORY FOR WEST FACING SHORES
OF THE BIG ISLAND AS WELL. IT SHOULD BE NOTED THAT THE SWELL AT BUOY
001 IS MORE NORTHERLY /322 DEGREES/ THAN THE WAVEWATCH INDICATED. IF
THIS TREND HOLDS...WE MAY NEED TO EXPAND THE ADVISORY TO NORTH
FACING SHORES OF THE BIG ISLAND AS WELL. GIVEN THE SIZE OF THE
SWELL...EVEN WITH A MORE NNW DIRECTION THERE SHOULD STILL BE ENOUGH
WRAP AROUND TO KEEP THE ADVISORY FOR THE KONA COAST.

SMALL CRAFT ADVISORIES ARE ALSO IN EFFECT FOR HAZARDOUS SEAS DUE TO
THE LARGE SWELL. THE CURRENT SCA RUNS THROUGH SUNDAY MORNING...BUT
MAY NEED TO BE EXTENDED AS YET ANOTHER LARGER SWELL IS EXPECTED TO
ARRIVE EARLY NEXT WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF WARNING UNTIL 10 AM HST SUNDAY FOR NORTH AND WEST FACING
SHORES OF NIIHAU KAUAI AND OAHU.

HIGH SURF ADVISORY UNTIL 4 PM HST SUNDAY FOR NORTH AND WEST FACING
SHORES OF MOLOKAI...NORTH FACING SHORES OF MAUI...AND WEST FACING
SHORES OF THE BIG ISLAND.

SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR WATERS FROM MAUI
NORTH.

SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 10 AM HST SUNDAY FOR
WATERS FROM THE ALENUIHAHA CHANNEL SOUTH.

&&

BRAVENDER