Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 231921
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
921 AM HST THU OCT 23 2014

.SYNOPSIS...
RELATIVELY WEAK HIGH PRESSURE NORTH OF THE ISLANDS WILL KEEP
TRADE WINDS ON THE LIGHT SIDE FOR SEVERAL MORE DAYS...WITH LAND
AND SEA BREEZES FOR MANY AREAS. CLOUDS AND SHOWERS WILL FAVOR
WINDWARD AND MAUKA AREAS...WITH A POCKET OF DRIER AIR BRINGING
FEWER SHOWERS AND MORE SUNSHINE FOR MONDAY AND TUESDAY.

&&

.DISCUSSION...
A WEAK PRESSURE GRADIENT CONTINUES OVER THE HAWAIIAN ISLANDS WITH
SURFACE WINDS ON THE LIGHTER SIDE. THIS IS DUE TO A LARGE AREA OF
LOW PRESSURE OVER THE NORTHEAST PACIFIC KEEPING THE SUBTROPICAL
RIDGE FARTHER S...NEAR 28N...AND MUCH WEAKER THAN NORMAL. HIGH
PRESSURE S OF THE ALEUTIANS IS GOING TO SLIDE QUICKLY SE AND TAKE
UP RESIDENCE OVER THE EAST PACIFIC THIS WEEKEND NEAR 32N 135W.
THIS WILL PROVIDE A WEAK REINFORCEMENT TO THE TRADES FOR SOME
AREAS STARTING LATER TODAY AND LASTING INTO NEXT WEEK...BUT NOT
ENOUGH TO OVERCOME THE DIURNAL LAND/SEA BREEZE CIRCULATIONS IN
MANY AREAS.

A SERIES OF WEAK TROUGHS IN THE EASTERLIES...WHICH ARE THE REMNANTS
OF AN OLD FRONTAL BOUNDARY THAT PASSED TO OUR NORTH SEVERAL DAYS
AGO...ARE BRINGING WAVES OF CLOUDS AND SHOWERS AS THEY MOVE OVER
THE ISLANDS. ONE SUCH WAVE MOVED OVER THE ISLANDS YESTERDAY AND IS
CURRENTLY ON THE WAY OUT. ANOTHER WEAKER TROUGH NEAR 152W SHOULD
MOVE THROUGH LATER TONIGHT AND FRIDAY MORNING...AND PERHAPS
ANOTHER WEAK ONE NEAR 140W THAT MAY NOT EVEN HOLD TOGETHER LONG
ENOUGH TO GET TO US. EACH ONE OF THESE CAN BRING A MINOR UPTICK IN
CLOUDS AND SHOWERS...MAINLY FOR WINDWARD AND MAUKA SECTIONS...WITH
FEWER SHOWERS AND MORE SUNSHINE IN BETWEEN. MUCH DRIER AIR IS
EXPECTED FOR MON AND TUE...WHICH SHOULD FAVOR RELATIVELY DRY
WEATHER. ALTHOUGH THE DEWPOINTS WILL LIKELY BE LOWER...THE
INCREASED SUNSHINE WILL MAKE THE DAYTIME HOURS STILL FEEL RATHER
HOT.

&&

.AVIATION...
A STRIPE OF ENHANCED MOISTURE ALONG AN OLD FRONTAL BOUNDARY WILL
SHIFT WEST OF THE STATE TODAY. AIRMET SIERRA FOR MOUNTAIN
OBSCURATION IS CURRENTLY IN EFFECT FOR PARTS OF THE STATE...BUT
WOULD EXPECT IMPROVING CONDITIONS BY MIDDAY AS A DRIER AIRMASS
SPREADS IN FROM THE EAST ALONG WITH INCREASING TRADE WINDS. VFR
WILL PREVAIL THIS AFTERNOON. CLOUDS AND SCATTERED SHOWERS WILL
LIKELY INCREASE ONCE AGAIN ACROSS WINDWARD SECTIONS TONIGHT...WITH
VFR CONTINUING ELSEWHERE.

&&

.MARINE...
A MINOR NORTHERLY BUMP...GENERATED BY LOW PRESSURE OVER THE GULF
OF ALASKA LAST WEEKEND...WILL ARRIVE ON NORTHERN SHORES TODAY BUT
FADE QUICKLY. THE FIRST LOW WEAKENED BUT HAS BEEN REPLACED BY A
STRONGER LOW. MOST OF THE SWELL ENERGY WITH THIS LOW WILL BE AIMED
TO THE EAST OF THE ISLANDS...BUT WE SHOULD CATCH THE WESTERN END
WHICH WILL BRING A SMALL NORTHERLY REINFORCEMENT FOR SATURDAY.

&&

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

&&

$$

DISCUSSION/MARINE...R BALLARD
AVIATION...JACOBSON





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