Flash Flood Warning 6, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST FRI DEC 3 2010

.SYNOPSIS...
A STRONG HIGH PRESSURE SYSTEM FAR NORTH OF THE STATE WILL BRING
STRONG TRADE WINDS ACROSS THE ISLANDS THROUGH TONIGHT AND DECREASING
THIS WEEKEND. A COLD FRONT IS CURRENTLY MOVING ACROSS THE STATE THIS
MORNING TOWARDS THE SOUTHWEST...PRODUCING FREQUENT SHOWERS...SOME
OF THEM HEAVY AT TIMES. THE FRONT WILL WEAKEN AND MOVE OFF THE
ISLANDS BY LATE THIS AFTERNOON. EXPECT DECREASING SHOWERS THROUGH
THE DAY AS A DRIER AND STABLE AIRMASS FILTERING IN THIS EVENING
WHICH WILL CONTINUE THROUGH THE WEEKEND. THE RIDGE TO THE NORTH WILL
WEAKEN RAPIDLY EARLY NEXT WEEK...WITH TRADES DECREASING TO LIGHT TO
MODERATE LEVELS.

&&

.DISCUSSION...
WINDY CONDITIONS ARE EXPECTED TODAY AND TONIGHT DRIVEN BY A STRONG
HIGH CENTERED FAR TO THE NORTH OF THE STATE. A COLD FRONT IS
CURRENTLY MOVING ACROSS THE STATE THIS MORNING. IT IS ADVANCING
TOWARDS THE WEST-SOUTHWEST AHEAD OF A DRY AND STABLE AIRMASS. THE
PRESSURE GRADIENT IS HOLDING STEADY BETWEEN BUOYS 51000 AND 51002 AT
AROUND A 7.0 MB DIFFERENCE. THE WINDS ARE CURRENTLY AT THEIR PEAK
ACROSS THE STATE THIS MORNING AS THE GRADIENT IS TIGHTEST ALONG THE
FRONT. THE WINDS WILL REMAIN STRONG THROUGH TONIGHT...DECREASING TO
FRESH TO LOCALLY STRONG BY SATURDAY MORNING AND GRADUALLY WEAKENING
BACK TO MODERATE LEVELS THROUGH THE REMAINDER OF THE WEEKEND. A WIND
ADVISORY REMAINS IN EFFECT FOR THE WINDIER AREAS OF MAUI COUNTY AND
THE BIG ISLAND THROUGH FRIDAY. WINDS AFFECTING THE HIGHER ELEVATIONS
ARE A LITTLE BIT WEAKER AS SHOWN FROM AUTOMATED OBSERVATIONS AND THE
12Z SOUNDING AT HILO...SO HAVE CANCELLED THE ADVISORY FOR HALEAKALA
SUMMIT AND THE BIG ISLAND INTERIOR.

FREQUENT TRADE WIND SHOWERS ARE EXPECTED TO CONTINUE THIS
MORNING....SOME OF THEM PRODUCING HEAVY RAINFALL AT TIMES ESPECIALLY
FOR WINDWARD AND MOUNTAIN LOCATIONS. GIVEN THE STRONG TRADE WINDS
...MANY OF THE SHOWERS WILL CARRY ONTO LEEWARD SIDES. THE FRONT WILL
WEAKEN AND MOVE OFF THE ISLANDS BY LATE THIS AFTERNOON....THOUGH A
FEW LINGERING SHOWERS ARE EXPECTED TO REMAIN AROUND THE AREA THROUGH
THE AFTERNOON HOURS. A DRY AND STABLE AIRMASS WILL FILTER IN THIS
EVENING WHICH WILL PRODUCE MOSTLY SUNNY SKIES AND LITTLE RAINFALL
SATURDAY AND SUNDAY. THE RIDGE TO THE NORTH WILL WEAKEN RAPIDLY
EARLY NEXT WEEK...WITH TRADES DECREASING TO LIGHT TO MODERATE
LEVELS. THERE IS ALSO SUFFICIENT CLOUD DEPTH TO PRODUCE SOME
FREEZING DRIZZLE THIS MORNING ABOVE 11000 FEET ON THE BIG ISLAND
SUMMITS AND HAVE A SLIGHT CHANCE OF FREEZING DRIZZLE IN THE FORECAST
THERE.

MEDIUM AND LONG RANGE MODELS ARE IN GOOD OVERALL AGREEMENT WITH
VEERING WINDS TO THE SOUTHEAST BEGINNING SUNDAY AND EVENTUALLY SOUTH
BY TUESDAY NIGHT. FOR SUNDAY THROUGH TUESDAY...A MUCH DRIER AND
STABLE AIRMASS WILL REMAIN IN PLACE OVER THE STATE AS THE SURFACE
RIDGE WEAKENS FURTHER AND SLIPS SOUTH AND EAST OF THE AREA WITH
WINDS VEERING TO MORE SOUTHERLY BY LATE TUESDAY AND WEDNESDAY. UNDER
THIS SCENARIO...THE THREAT OF SHOWERS WILL INCREASE BY THE MIDDLE OF
NEXT WEEK. HAVE UNDERCUT GUIDANCE POPS AND GONE WITH A CHANCE OF
SHOWERS PRETTY MUCH STATE-WIDE ALLOWING FOR FUTURE SHIFTS TO TREND
POPS UP IF GOOD MODEL AGREEMENT CONTINUES.

&&

.AVIATION...
STRONG HIGH PRES N OF THE AREA WILL MAINTAIN 15-30KT TRADES ACROSS
THE AREA WITH STRONGER WINDS THRU RIDGES AND OVER MOUNTAINS. A
DISSIPATING CDFNT OVER THE STATE WILL BRING TEMPO MVFR CONDITIONS TO
WINDWARD AREAS TODAY. THE TRADES WILL CONTINUE TO PRODUCE LLVL TURB
LEE OF THE MT.

&&

.MARINE...
TRADES WINDS WILL REMAIN STRONG INTO SATURDAY MORNING BEFORE
DECLINING FOR THE REST OF THE WEEKEND. A GALE WARNING IS IN EFFECT
FOR THE WINDIER WATERS AROUND THE ISLAND OF MAUI AND THE BIG ISLAND
THROUGH LATE THIS AFTERNOON. THE GALE WARNINGS WILL EITHER BE
EXTENDED FOR TONIGHT OR REPLACED WITH SMALL CRAFT ADVISORIES FOR
THOSE AFFECTED ZONES. SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED FOR
THE REMAINDER OF THE HAWAIIAN COASTAL WATERS THROUGH SATURDAY
MORNING.

THE CHOPPY TRADE SWELL WILL RESULT IN HIGH SURF ADVISORY LEVEL SURF
ALONG EAST FACING SHORES OF ALL ISLANDS THROUGH EARLY SATURDAY
MORNING.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
GALE WARNING UNTIL 6 PM HST THIS EVENING FOR MAALAEA BAY-PAILOLO
CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND
SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST SATURDAY FOR ALL OTHER COASTAL
WATERS.

HIGH SURF ADVISORY UNTIL 6 AM HST SATURDAY FOR FOR EAST FACING
SHORES OF NIIHAU...KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG
ISLAND.

WIND ADVISORY UNTIL 6 PM HST THIS EVENING FOR LANAI-KAHOOLAWE-
MAUI LEEWARD WEST-MAUI CENTRAL VALLEY-LEEWARD HALEAKALA-SOUTH
BIG ISLAND-BIG ISLAND NORTH AND EAST-KOHALA.

&&

DISCUSSION/MARINE...FOSTER
AVIATION...MORRISON