Flash Flood Watch 6, NWS Honolulu, HI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST WED MAR 2 2011

.SYNOPSIS...
WINDS WILL TURN SOUTHERLY AND STRENGTHEN THROUGH THURSDAY...
AHEAD OF A LOW PRESSURE SYSTEM DEVELOPING WEST OF THE STATE. THIS
SYSTEM WILL PASS NORTH OF THE ISLANDS...BRINGING A COLD FRONT TO
KAUAI ON FRIDAY. THE FRONT WILL WEAKEN AS IT PUSHES ACROSS THE
CENTRAL ISLANDS THROUGH SATURDAY. STRONG WINDS AND WIDESPREAD
SHOWERS ARE POSSIBLE AHEAD OF AND ALONG THE FRONT.

&&

.DISCUSSION...
TRADE WINDS CONTINUE TO HANG ON AT THE SURFACE THIS EVENING...AS
AIRPORTS ACROSS THE STATE STILL REPORTED EASTERLY WINDS. SKIES ARE
CLOUDY AS A THICKER LAYER OF HIGH LEVEL CLOUDS COVERED THE STATE
THIS EVENING. THERE ARE SOME LOW CLOUDS IN THE ISLAND VICINITY AND
ARE AFFECTING MAINLY WINDWARD AND MOUNTAIN AREAS...BRINGING SOME
LIGHT SHOWERS. RAINFALL TOTALS REMAIN ON THE LOWER SIDE AS
EXPECTED...AS AIR MASS IN THE ISLAND VICINITY REMAINS STABLE AND
RELATIVELY DRIER. LOOKS LIKE MAINLY FAIR WEATHER WILL HOLD FOR THE
ISLANDS AT LEAST THROUGH REST OF THIS EVENING. RADAR DATA DO SHOW
SOME HEAVIER SHOWERS LURKING FURTHER SOUTH OF KAUAI AT TIME. THESE
HEAVIER SHOWERS MAY EVENTUALLY REACH THE ISLAND BY EARLY
THURSDAY...UNDER THE INCREASING SOUTHERLY WIND FLOW.

CHANGES IN THE WEATHER ARE COMING...AS A SURFACE TROUGH OF LOW
PRESSURE DEEPENS WEST OF THE STATE THIS EVENING. HIGH CLOUDS FROM
THE CONVECTION ASSOCIATED WITH THIS TROUGH ARE ALREADY AFFECTING THE
ISLANDS SINCE EARLIER TODAY. LATEST FORECAST CHARTS ARE IN FAIR
AGREEMENT UPON THE EVOLUTION OF THIS PENDING SYSTEM. LOOKS LIKE A
SERIES OF LOW PRESSURE SYSTEMS MAY DEVELOP ALONG THIS TROUGH AS IT
LIFTS EAST NORTHEASTWARD. MUCH OF THE SYSTEM WILL PASS NORTH OF THE
STATE BEGINNING LATE THURSDAY...WITH A TRAILING FRONT APPROACHING
THE ISLANDS LATE THURSDAY. AHEAD OF THIS PENDING SYSTEM...SURFACE
WINDS WILL VEER TO THE SOUTHEAST THEN SOUTH BY THURSDAY MORNING. THE
DEEP LAYER SOUTHERLY FLOW WILL DRAW WARM AND MOIST AIR FROM THE
TROPICS TO THE ISLANDS. LOOK FOR INCREASING LOW CLOUDS AND
PRECIPITATION OVER THE WESTERN ISLANDS BY THURSDAY AS THE WARM MOIST
SOUTHERLY FLOW FULLY DEVELOPS. LATEST FORECAST CHARTS ALSO HAVE
BETTER AGREEMENT UPON THE STRONGER SURFACE WINDS DEVELOPING AHEAD OF
THE PENDING FRONT. LOOK FOR SOUTHERLY WINDS TO STRENGTHEN
THURSDAY...SPECIALLY NEAR KAUAI...THEN SPREADING TO OAHU BY THURSDAY
NIGHT AND MAY REACH MAUI COUNTY BY EARLY FRIDAY. STILL BELIEVE THE
STRONG SURFACE WINDS MAY STAY BELOW ADVISORY LEVEL AT THIS TIME...
THOUGH THERE IS ALWAYS A CERTAIN AMOUNT OF UNCERTAINTY PERTAINING TO
DEVELOPING SYSTEM LIKE THIS ONE. ON THE OTHER HAND...WINDS AT THE
HIGHER ELEVATIONS ARE EXPECTED TO REACH WARNING LEVEL THURSDAY NIGHT
AND FRIDAY AS AN UPPER LEVEL JET MOVES ACROSS THE AREA. A HIGH WIND
WATCH IS ISSUED FOR THE SUMMITS OF HALEAKALA...MAUNA KEA...AND MAUNA
LOA FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON.

AM STILL NOT TOO IMPRESS WITH THE DYNAMICS OF THIS SYSTEM...THOUGH
THERE MAY BE ENOUGH INSTABILITY FOR THUNDERSTORMS TO DEVELOP AHEAD
AND NEAR THE PENDING FRONT. IN FACT...STRONG WINDS ASSOCIATED WITH
THE THUNDERSTORMS MAY BECOME A PROBLEM UNDER THIS TYPICAL OF
ATMOSPHERIC ENVIRONMENT. THUS THE CHANCE OF THUNDERSTORMS REMAIN
HIGHEST FOR THE WESTERN ISLANDS FROM LATE THURSDAY THROUGH FRIDAY.

THE FRONT WILL ADVANCE THROUGH THE ISLAND CHAIN FRIDAY INTO
SATURDAY...THEN SLOWLY WEAKEN INTO A TROUGH AS THE MAIN DYNAMICS
ASSOCIATED WITH THE SYSTEM LIFTS FURTHER NORTH. MOISTURE FROM THE
WEAKENING FRONT WILL LINGER IN THE ISLAND VICINITY OVER THE WEEKEND.
HIGH PRESSURE IS EXPECTED TO BUILD NORTH OF THE STATE BEHIND THE
FRONT...AND WILL BRING TRADE WINDS BACK TO THE ISLANDS BY EARLY NEXT
WEEK. LOOK FOR WETTER TRADE WIND WEATHER TO RETURN TO ALL THE
ISLANDS BY EARLY NEXT WEEK...AS LINGERING MOISTURE WILL PROVIDE
SHOWERS TO THE STATE.

&&

.MARINE...
A SMALL CRAFT ADVISORY FOR THE WESTERN COASTAL WATERS WILL BE IN
EFFECT EARLY THURSDAY MORNING DUE TO THE PENDING INCREASE OF
WINDS AND SEAS.

A GALE WARNING WILL ALSO BE IN EFFECT FOR THURSDAY NIGHT AND FRIDAY
AS GALE FORCE WINDS MOST LIKELY DEVELOPING NEAR THE FRONT...IN THE
AREA GENERALLY NORTH OF THE HAWAIIAN COASTAL WATERS.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON
FOR HALEAKALA SUMMIT-BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO 6 PM HST FRIDAY FOR
WATERS SURROUNDING KAUAI...OAHU...AND LEEWARD MAUI COUNTY.

&&

HUI