Wildfire in Hawaii, August 3 to 4, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST WED AUG 3 2011

.SYNOPSIS...
TRADE WINDS WILL INCREASE THROUGH THE END OF THE WEEK...AS HIGH
PRESSURE STRENGTHENS FAR NORTH NORTHEAST OF THE STATE. WINDS WILL
PEAK ON FRIDAY AND SATURDAY...AND START TO DIMINISH EARLY NEXT WEEK.
SHOWERS WILL BE GREATEST IN COVERAGE AT NIGHT AND IN THE MORNING...
AND MAINLY FOCUSED ACROSS WINDWARD AND MAUKA AREAS.

&&

.DISCUSSION...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH FAR NORTHEAST OF THE
STATE...WHICH IS BUILDING WESTWARD. AT THE SURFACE...HIGH PRESSURE
IS LOCATED FAR NORTH NORTHEAST OF THE STATE. THE HIGH IS NEARLY
STATIONARY AND STARTING TO STRENGTHEN. 12Z SOUNDINGS FROM HILO AND
LIHUE SHOW INVERSIONS NEAR 6-7KFT...WITH PRECIPITABLE WATERS OF
1.1-1.2 INCHES. THE MORNING AMSU/SSMI BLENDED TOTAL PRECIPITABLE
WATER IMAGERY SHOWS SIMILAR VALUES EXTENDING 500 MILES UPSTREAM TO
THE NORTHEAST...WITH PATCHES OF EVEN DRIER AIR /PW VALUES 0.7-1.0
INCHES/ EMBEDDED WITHIN THIS AREA FARTHER TO THE EAST.

THE 12Z GFS/NAM/ECMWF SHOW THE HIGH NORTH NORTHEAST OF THE STATE
STRENGTHENING THROUGH FRIDAY AS UPPER LEVEL HEIGHTS BUILD ACROSS THE
CENTRAL PACIFIC. THE INCREASING GRADIENT SOUTH OF THE HIGH WILL LEAD
TO STRONGER TRADE WINDS ACROSS THE ISLANDS...WHICH ARE EXPECTED TO
CONTINUE INTO THE WEEKEND. THE GRADIENT WILL BE STRONGEST
FRIDAY/SATURDAY...AND WINDS COULD BE RATHER STRONG AND GUSTY. BASED
ON SURFACE OBSERVATIONS AND SCATTEROMETER DATA...WINDS ARE ALREADY A
TOUCH STRONGER TODAY THAN YESTERDAY...ALTHOUGH BUOYS HAVE NOT SHOWN
THAT MUCH OF AN INCREASE IN THE PRESSURE GRADIENT ACROSS THE STATE
YET.

THE OVERALL MOISTURE CONTENT OF THE AIRMASS IS SLIGHTLY DRIER THAN
NORMAL...WITH PRECIPITABLE WATER VALUES BELOW THE AVERAGE OF 1.4
INCHES FOR AUGUST. HOWEVER...MOISTURE IS ABUNDANT AT LOW LEVELS
BELOW THE SUBSIDENCE INVERSION. THIS MOISTURE IS EVIDENCED BY THE
CUMULUS/STRATOCUMULUS FIELD AROUND THE STATE...AND ALSO THE RAINFALL
REPORTS FROM GAGES OVERNIGHT. FORECAST SOUNDINGS SHOW INVERSIONS
REMAINING RELATIVELY STEADY THROUGH THE PERIOD...AND THE MOISTURE
WILL STILL BE PRESENT BUT SOMEWHAT SHALLOW. CLOUDS AND SHOWERS WILL
BE FOCUSED ACROSS WINDWARD SECTIONS AT NIGHT AND DURING THE MORNING.
WITH THE SHALLOW MOISTURE...CLOUDS WILL SCATTER OUT MORE DURING THE
AFTERNOON. /THE EXCEPTION IS WITH THE LEEWARD BIG ISLAND...WHERE
CLOUDS WILL FILL IN ACROSS UPSLOPE AREAS DURING THE AFTERNOONS./ IN
ADDITION...THE STRENGTHENING WINDS WILL BLOW LIGHT SHOWERS ACROSS
LEEWARD SECTIONS OF THE SMALLER ISLANDS MORE OFTEN.

A LINGERING MID-LEVEL TROUGH CURRENTLY NORTHWEST OF THE STATE WILL
MOVE WEST AND WEAKEN...ALLOWING A MUCH STRONGER MID-LEVEL FLOW TO
DEVELOP. THE 12Z GFS SHOWS THE 700MB HEIGHT GRADIENT REALLY
STRENGTHENING TONIGHT AND THURSDAY. THE CURRENT FORECAST HAS
ADVISORY LEVEL WINDS ACROSS HALEAKALA SUMMIT BEGINNING TONIGHT. THE
GFS HAS BEEN PRETTY CONSISTENT IN THIS REGARD FOR THE PAST FEW MODEL
RUNS...AND A WIND ADVISORY WILL LIKELY BE ISSUED THIS AFTERNOON.
WINDS ARE ALSO EXPECTED TO INCREASE ACROSS THE BIG ISLAND SUMMITS...
BUT NOT TO THE EXTENT AS WINDS ACROSS HALEAKALA.

AFTER REACHING ITS PEAK STRENGTH FRIDAY/SATURDAY...THE SURFACE HIGH
WILL SLOWLY WEAKEN SUNDAY AND MONDAY AS MID/UPPER-LEVEL HEIGHTS
START FALLING. THE 12Z GFS AND ECMWF BOTH SHOW AN UPPER LEVEL LOW
DEVELOPING NORTHEAST OF THE STATE BY SUNDAY...WITH THE ECMWF DEEPER
AND SLIGHTLY FASTER. IN ADDITION TO THE WEAKER SURFACE GRADIENT...A
TROUGH ASSOCIATED WITH THIS LOW NEAR THE ISLANDS WILL ALSO CAUSE
INVERSION HEIGHTS TO RISE EARLY NEXT WEEK. /12Z GFS FORECAST
SOUNDINGS SHOW A SLIGHT INCREASE ON SUNDAY...WITH A MUCH WEAKER AND
HIGHER INVERSION BY MONDAY./ THIS WOULD LEAD TO GREATER SHOWER
COVERAGE AND INTENSITY FOR THE FIRST HALF OF THE WORK WEEK.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT ALL TAF LOCATIONS THROUGHOUT THE DAY.
SCATTERED MVFR CONDITIONS WITH ISOLATED -SHRA CAN BE EXPECTED OVER
WINDWARD SLOPES AND SUMMITS DUE TO MOISTURE EMBEDDED IN THE TRADES.

THE TRADE WINDS WILL GRADUALLY BE INCREASING OVER THE NEXT COUPLE OF
DAYS. THIS WILL CAUSE AN INCREASE IN LOW LEVEL TURBULENCE SOUTH AND
WEST OF MOUNTAIN RANGES. AN AIRMET FOR LOW LEVEL TURBULENCE WILL
LIKELY BE NEEDED AS EARLY AS THURSDAY MORNING FOR THESE CONDITIONS.

&&

.MARINE...
AS THE HIGH FAR NORTH NORTHEAST OF THE STATE STRENGTHENS THROUGH
FRIDAY...WINDS WILL STEADILY INCREASE ACROSS THE COASTAL WATERS. A
SMALL CRAFT ADVISORY FOR THE TYPICALLY WINDIER LOCATIONS NEAR MAUI
AND THE BIG ISLAND IS NOW IN EFFECT THROUGH SATURDAY...AND IT IS
EXPECTED THAT ADDITIONAL MARINE ZONES WILL BE ADDED TO IT AS THE
WEEK PROGRESSES. WINDS ARE EXPECTED TO BE STRONGEST
FRIDAY/SATURDAY...AND BEGIN TO DIMINISH ON SUNDAY.

A LONG PERIOD SOUTH SWELL WILL PEAK TONIGHT/THURSDAY...THEN SLOWLY
SUBSIDE THROUGH THE END OF THE WEEK. FOR EAST FACING SHORES...ROUGH
AND CHOPPY SURF WILL BUILD OVER THE NEXT FEW DAYS AS THE TRADE WINDS
STRENGTHEN. 12Z WAVEWATCH III GUIDANCE SHOWS A SMALL...LONG PERIOD
WEST SWELL FROM TYPHOON MUIFA REACHING THE ISLANDS OVER THE WEEKEND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FROM UNTIL 6 PM HST SATURDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.

&&

PUBLIC/MARINE...BRAVENDER
AVIATION...BURKE