Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 302031
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST THU JUL 30 2015

.SYNOPSIS...
HIGH PRESSURE FAR NORTHEAST OF THE STATE AND A SERIES OF WEAK
TROPICAL DISTURBANCES PASSING TO THE SOUTH WILL MAINTAIN LOCALLY
BREEZY TRADE WINDS THROUGH THE WEEKEND. THE TRADES WILL BRING SOME
SHOWERS TO WINDWARD AREAS...MOSTLY DURING NIGHTS AND MORNINGS.
REMNANT MOISTURE FROM A FORMER TROPICAL DEPRESSION MAY AFFECT THE
ISLANDS OVER THE WEEKEND...BRINGING MUGGY WEATHER AND INCREASED
SHOWERS FOR WINDWARD AREAS...ESPECIALLY FOR THE BIG ISLAND.

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH SOUTHEAST OF THE
STATE...WITH A RIDGE EXTENDING OVER THE ISLANDS. AT THE SURFACE...
HIGH PRESSURE IS LOCATED FAR NORTHEAST OF THE STATE. THE REMNANT LOW
THAT WAS TROPICAL DEPRESSION EIGHT-E IS LOCATED FAR EAST OF THE BIG
ISLAND...AND TROPICAL STORM GUILLERMO IS FAR TO THE EAST-SOUTHEAST.
12Z SOUNDING FROM LIHUE SHOWED AN INVERSION NEAR 4-5KFT AND A
PRECIPITABLE WATER OF 1.4 INCHES. EARLY MORNING TOTAL PRECIPITABLE
WATER IMAGERY SHOWS SIMILAR TO SLIGHTLY HIGHER VALUES OVER AND
UPSTREAM OF THE STATE...WITH MUCH HIGHER VALUES IN EXCESS OF 2
INCHES NEAR 140W ASSOCIATED WITH THE FORMER TROPICAL DEPRESSION.

A TYPICAL TRADE WIND PASTERN IS EXPECTED FOR THE NEXT COUPLE DAYS.
BETWEEN THE HIGH TO THE NORTHEAST AND A LOW PASSING FAR SOUTH OF THE
STATE...THE GRADIENT ACROSS THE ISLANDS WILL SUPPORT LOCALLY BREEZY
TRADE WINDS. SHOWERS HAVE BEEN FOCUSED ACROSS WINDWARD SECTIONS...
WITH RAINFALL AMOUNTS GENERALLY A TENTH OF AN INCH OR LESS OVER THE
PAST 12 HOURS. FORECAST SOUNDINGS/TIME SECTIONS SHOW INVERSIONS AND
MOISTURE DEPTH REMAINING STEADY THROUGH THE END OF THE WEEK. A
SIMILAR WEATHER PATTERN IS EXPECTED THROUGH FRIDAY NIGHT...WITH
SHOWERS FOCUSED MAINLY ACROSS WINDWARD SECTIONS...GREATEST AT NIGHT
AND DURING THE MORNING...WITH SOME SHOWERS ACROSS LEEWARD BIG ISLAND
AND MAUI DURING THE AFTERNOON.

FORMER TROPICAL DEPRESSION EIGHT-E IS EXPECTED TO MOVE
WEST-SOUTHWEST AND PASS BY SOUTH OF THE STATE OVER THE WEEKEND. THE
MAIN IMPACT EXPECTED FOR HAWAII WILL BE AN INCREASE IN MOISTURE...AS
WELL AS A CONTINUED ENHANCEMENT TO THE TRADE WINDS. 12Z MODELS SHOW
MOST OF THE MOISTURE ASSOCIATED WITH THE FORMER DEPRESSION IMPACTING
EAST AND SOUTHEAST SECTIONS OF THE BIG ISLAND. THERE IS THE
POTENTIAL FOR SOME OF THIS DEEPER TROPICAL MOISTURE TO SPREAD TO THE
SMALLER ISLANDS AS WELL...BUT 12Z GFS/ECMWF HAVE BACKED AWAY FROM
THIS AND NOW FOCUS THE BULK OF THE SHOWERS FROM THE BIG ISLAND
SOUTHWARD. MOISTURE DEPTH WILL LIKELY EXTEND UP TO SUMMIT
LEVEL...THOUGH TEMPERATURES ARE EXPECTED TO REMAIN ABOVE FREEZING
THROUGH THE PERIOD.

THE NATIONAL HURRICANE CENTER IN MIAMI IS ISSUING BULLETINS ON
TROPICAL STORM GUILLERMO...WHICH IS NEARLY 2000 MILES EAST-SOUTHEAST
OF HILO. THE CURRENT FORECAST IS FOR GUILLERMO TO MOVE
WEST-NORTHWEST AND STRENGTHEN...POTENTIALLY CROSSING 140W INTO THE
CENTRAL PACIFIC HURRICANE CENTER AREA OF RESPONSIBILITY ON SATURDAY.
IMPACTS TO HAWAII WILL BE VERY GREATLY DEPENDING UPON THE TRACK AND
SPEED OF THE SYSTEM...WHICH IS HIGHLY UNCERTAIN THIS FAR OUT IN TIME.

&&

.AVIATION...
EXPECT TRADE WINDS TO INCREASE TO MODERATE TO LOCALLY BREEZY TODAY
AND MAINTAIN THROUGH THE PERIOD. AS OF 20Z WIND SPEEDS ARE BELOW THE
THRESHOLD FOR WIDESPREAD LOW LEVEL TURB...HOWEVER SOME AREAS MAY
EXPERIENCE LOCALIZED LIGHT TO MOD TURB IN THE LEE OF THE TERRAIN.
WE WILL CONTINUE TO MONITOR AND AIRMET TANGO FOR LOW LEVEL TURB MAY
BE NEEDED LATER.

CLOUDS AND SHOWERS WILL FOCUS ALONG WINDWARD AND MOUNTAIN
AREAS...WITH PREVAILING VFR CIGS/VIS AT ALL ISLAND TERMINALS.

AN UPPER LEVEL JET A FEW HUNDRED MILES NORTHWEST OF KAUAI MAY
PRODUCE ISOL LIGHT TO MOD TURB BETWEEN FL300 TO FL450 NORTHWEST OF
THE AREA.

&&

.FIRE WEATHER...
WITH LOCALLY BREEZY TRADE WINDS...WE MAY REACH THE RED FLAG WIND
THRESHOLD OF 18KT AGAIN. HOWEVER...DEWPOINTS ARE SLIGHTLY HIGHER
THAN YESTERDAY...AND WE ARE NOT EXPECTED TO REACH THE RELATIVE
HUMIDITY THRESHOLD OF 45 PERCENT. THEREFORE A RED FLAG WARNING IN
NOT ANTICIPATED...BUT FIRE DANGER THREAT REMAINS ELEVATED.

&&

.MARINE...
A SMALL CRAFT ADVISORY CONTINUES FOR THE TYPICALLY WINDIER AREAS
NEAR MAUI AND THE BIG ISLAND. AS THE REMNANT LOW THAT WAS FORMER
DEPRESSION EIGHT-E PASSES SOUTH OF THE STATE...IT MAY STRENGTHEN THE
GRADIENT ENOUGH TO WARRANT EXPANSION OF THE ADVISORY TO ADDITIONAL
CHANNELS NEAR KAUAI AND OAHU.

NO MAJOR SWELLS ARE EXPECTED FOR THE NEXT SEVERAL DAYS. SURF IS
EXPECTED TO REMAIN BELOW THE ADVISORY THRESHOLD ALONG ALL SHORES.

THE NATIONAL HURRICANE CENTER IN MIAMI IS ISSUING BULLETINS ON
TROPICAL STORM GUILLERMO...WHICH IS NEARLY 2000 MILES EAST-SOUTHEAST
OF HILO. THE CURRENT FORECAST IS FOR GUILLERMO TO MOVE
WEST-NORTHWEST AND STRENGTHEN...POTENTIALLY CROSSING 140W INTO THE
CENTRAL PACIFIC HURRICANE CENTER AREA OF RESPONSIBILITY ON SATURDAY.
IMPACTS TO HAWAII WILL BE VERY GREATLY DEPENDING UPON THE TRACK AND
SPEED OF THE SYSTEM...WHICH IS HIGHLY UNCERTAIN THIS FAR OUT IN TIME.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR THE PAILOLO AND
ALENUIHAHA CHANNELS...MAALAEA BAY...AND WATERS SOUTH OF THE BIG
ISLAND.

&&

$$

BRAVENDER/EATON




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