424
FXHW60 PHFO 091342 CCA
AFDHFO
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE FEB 9 2010
SYNOPSIS
MODERATE TRADE WINDS AND DRY CONDITIONS WILL PREVAIL THROUGH EARLY
WEDNESDAY. A WEAKENING COLD FRONT WILL BRING A FEW SHOWERS TO KAUAI
AND OAHU BY LATE WEDNESDAY BEFORE DISSIPATING. THE TRADES WILL
FRESHEN FROM THURSDAY INTO FRIDAY...AND THEN DIMINISH SLIGHTLY INTO
THE WEEKEND.
DISCUSSION
OBSERVATIONS ACROSS THE MAIN HAWAIIAN ISLANDS REPORTED LIGHT TO
MODERATE TRADE WINDS...AND STILL VIRTUALLY NO RAIN. ALOFT...RIDGING
STRENGTHENED THROUGH A DEEP LAYER FROM THE WEST...PROVIDING AMPLE
SUBSIDENCE...AS SHOWN BY THE LOW INVERSION BASE IN LOCAL SOUNDINGS.
THE AIR MASS THROUGH THE MIXED LAYER REMAINED ATYPICALLY DRY.
TROUGHING ALOFT LANGUISHING TO THE EAST OF THE ISLANDS TIGHTENED THE
GRADIENT OVER THE SOUTHEAST PART OF THE STATE AT MID-LEVELS...
PRODUCING INCREASED WINDS OVER HIGHER ELEVATIONS OF THE BIG ISLAND.
HOWEVER...THESE WINDS HAD FALLEN BELOW THE CRITERION FOR A WIND
ADVISORY...AND WILL DIMINISH FURTHER AS THE TROUGH MOVES EAST.
MARINE STRATOCUMULI PASSING UNDER THE TROUGH DEVELOPED NOTICEABLY...
AND PERHAPS SOME OF THESE MIGHT BRING A SPRINKLE OR TWO TO EAST
SHORES OF THE BIG ISLAND TODAY. POPS HAVE BEEN INCREASED SLIGHTLY
FOR THAT AREA...BUT EVEN SO WINDWARD SHOWERS WILL REMAIN MUCH LESS
PREVALENT THAN USUAL.
DRY TRADES WILL CONTINUE THROUGH TONIGHT...WHEN THE NEXT FRONT WILL
APPROACH THE STATE FROM THE NORTHWEST. ALTHOUGH GUIDANCE PREDICTS
THIS FEATURE TO REACH FAR ENOUGH SOUTH TO BRUSH THE ISLANDS AS IT
PASSES...THE ACCOMPANYING TROUGH ALOFT WILL MAKE ONLY A SMALL DENT
IN THE PREVAILING RIDGE. WITHOUT ADEQUATE SUPPORT...THE FRONT NEAR
THE SURFACE LIKELY WILL STALL OUT EVEN BEFORE REACHING KAUAI.
INDEED...ITS MAIN LOCAL EFFECTS MAY BE LIMITED TO WEAKENING THE
TRADES BRIEFLY BEFORE IT ARRIVES...AND PROVIDING A LITTLE EXTRA
MOISTURE FOR TRADE-WIND SHOWERS FROM TUESDAY NIGHT INTO THURSDAY
AFTER IT DISINTEGRATES.
THE TRADE WINDS WILL INCREASE SOMEWHAT FROM WEDNESDAY INTO EARLY
FRIDAY AS THE SUBTROPICAL RIDGE RECOVERS...BUT THEN WILL WEAKEN
AGAIN BY LATE FRIDAY AHEAD OF THE NEXT FRONT. MOST SOLUTIONS STILL
PORTRAY THIS FEATURE AS BEING LESS IMPRESSIVE THAN THE ONE DUE
EARLIER IN THE WEEK...SO DRY TRADE WINDS LIKELY WILL PERSIST THROUGH
THE COMING WEEKEND...ALBEIT AT SLIGHTLY LOWER SPEEDS.
GUIDANCE STARTS TO DISAGREE MORE BY MONDAY. SOME SOLUTIONS WEAR AWAY
THE RIDGE ALOFT OVER THE ISLANDS...WHILE OTHERS BRING A STRONGER
MID-LEVEL TROUGH AS A DISTINCT FEATURE. IN ANY CASE...IT LOOKS LIKE
A FRONT APPROACHING THE STATE EARLY NEXT WEEK MIGHT HAVE A LITTLE
MORE SUPPORT ALOFT...AND SO MAY ACTUALLY PRODUCE A BIT OF RAIN.
MARINE
SURF IS EXPECTED TO RISE SIGNIFICANTLY LATE TODAY ALONG NORTH AND
WEST SHORES. A NORTHWEST SWELL GENERATED BY A LARGE AND INTENSE
STORM SYSTEM FAR NORTHWEST OF THE MAIN HAWAIIAN ISLANDS WILL BRING
SURF HEIGHTS TO WARNING LEVELS FROM THIS EVENING THROUGH THURSDAY...
BEFORE LOWERING TO ADVISORY LEVELS ON FRIDAY. A REINFORCING SMALLER
NORTHWEST SWELL IS EXPECTED TO COME IN ON SATURDAY AND MAINTAIN
ADVISORY-LEVEL SURF INTO THE WEEKEND.
A SOUTH SWELL WILL ARRIVE ON WEDNESDAY AND PEAK LATE WEDNESDAY NIGHT
THROUGH THURSDAY MORNING ALONG SOUTH-FACING SHORES. THE SURF FROM
THIS SWELL HAS THE POTENTIAL TO REACH THE 8-FOOT HIGH SURF ADVISORY
THRESHOLD FOR SOUTH-FACING SHORES.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
RYSHKO
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