Wildfire in Hawaii, November 25 to 28, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
325 PM HST MON NOV 25 2013

.SYNOPSIS...
TRADE WINDS WILL DELIVER CLOUDS AND LIMITED LIGHT SHOWERS TO
WINDWARD AREAS THROUGH WEDNESDAY...BUT CONDITIONS WILL BE MOSTLY
DRY. WINDS WILL WEAKEN AND VEER SOUTHEAST THURSDAY...BRINGING HAZY
SKIES TO THE SMALLER ISLANDS. SOUTHERLY WINDS ARE EXPECTED TO BRING
INCREASING SHOWERS...AND THE POTENTIAL FOR HEAVY RAIN AND
THUNDERSTORMS...FROM LATE FRIDAY INTO SUNDAY AS A FRONT APPROACHES.

&&

.DISCUSSION...
MODERATE TRADES ARE CURRENTLY BEING SUPPORTED BY A RELATIVELY WEAK
HIGH LOCATED NOT TOO FAR NE OF THE ISLANDS...AND ITS ASSOCIATED
RIDGE THAT EXTENDS W ALONG 25N. THE ISLAND ATMOSPHERE IS STRONGLY
CAPPED...WITH AFTERNOON SOUNDINGS DEPICTING AN INVERSION BASE
BETWEEN 5 AND 7 KFT...WHICH IS PREVENTING THE FEW LOW CLOUDS NEAR
THE ISLANDS FROM PRODUCING MUCH IN THE WAY OF RAINFALL. VISIBLE
SATELLITE IMAGERY CONTINUES TO SHOW FEW TO SCATTERED LOW CLOUDS OVER
WINDWARD WATERS FROM KAUAI TO MAUI...AND GREATER AMOUNTS OF LOW
CLOUD OVER BIG ISLAND WINDWARD WATERS. OVER THE ISLANDS HOWEVER...
BROKEN LOW CLOUDS HAVE PERSISTED OVER MOST WINDWARD SLOPES THROUGH
THE DAY...WHILE SOME LEEWARD AREAS HAVE SEEN A MODEST INCREASE IN
LOW CLOUD COVER DURING THE AFTERNOON.

A RELATIVELY WEAK FRONT NOW PASSING ABOUT 350 MILES N OF KAUAI
WILL MOVE STEADILY E THROUGH TOMORROW...AS A QUICK-MOVING HIGH
PRESSURE CELL PASSES WELL N OF THE ISLANDS IN THE WAKE OF THE FRONT.
THE PASSING OF THIS HIGH IS EXPECTED TO LEAD TO A TIGHTENING OF THE
PRESSURE GRADIENT NEAR THE ISLANDS TONIGHT...WITH TRADE WINDS
INCREASING SLIGHTLY IN RESPONSE. BY TUESDAY NIGHT/WEDNESDAY THE HIGH
WILL MOVE TO A POSITION FAR NE OF THE ISLANDS...AND IT/S ASSOCIATED
RIDGE WILL BE MOVING TOWARD THE ISLANDS FROM THE NW...AS A STRONGER
FRONT...CURRENTLY NEAR MIDWAY ATOLL...BEGINS TO DRAW CLOSER. WINDS
WILL WEAKEN AND VEER TO THE SE FROM LATE TUESDAY INTO THURSDAY.
THESE SE WINDS WILL SPREAD VOLCANIC HAZE FROM SE BIG ISLAND TO THE
SMALLER ISLANDS...AND TO OTHER AREAS ON THE BIG ISLAND.

A DEEP LAYER RIDGE WILL BE OVER/NEAR THE ISLANDS THROUGH WEDNESDAY...
THEREBY MAINTAINING A STRONG SUBSIDENCE INVERSION AND WARM MID-LEVEL
TEMPS THAT WILL KEEP THE LIMITED LOW CLOUD FIELD FROM PRODUCING MUCH
IN THE WAY OF PRECIP. BRIEF AND LIGHT WINDWARD SHOWERS REPRESENT THE
GREATEST CHANCE OF ANY RAINFALL AS MOSTLY DRY CONDITIONS PREVAIL.
WITH LIGHT SE WINDS ON THURSDAY...THE FOCUS FOR CLOUDS AND SHOWERS
WILL LIKELY SHIFT TO LEEWARD AND INTERIOR AREAS DURING THE
AFTERNOON AS SEA BREEZES CONVERGE OVER THE ISLANDS. A SIMILAR
PATTERN IS POSSIBLE IN SOME AREAS ON FRIDAY...BUT INCREASING S WINDS
MAY OVERRIDE SEA BREEZE CIRCULATIONS ON KAUAI AND OAHU.

THE AIR MASS IS EXPECTED TO BECOME INCREASINGLY MOIST AND UNSTABLE
TOWARD WEEK/S END...AS THE SURFACE RIDGE MOVES S OF THE ISLANDS...
AND A DEEP LAYER TROUGH AND SURFACE FRONT DRAW EVER CLOSER FROM THE
NW. SOUTHERLY WINDS WILL INCREASE RAIN CHANCES OVER KAUAI AND OAHU
FRIDAY...AND THE REST OF THE STATE FRIDAY NIGHT INTO THE WEEKEND.
COLD AIR ALOFT WILL ACT TO DESTABILIZE THE ATMOSPHERE AND
THUNDERSTORMS WITH HEAVY RAIN WILL BE POSSIBLE FRIDAY AND SATURDAY.
WHILE FORECAST MODELS ARE SHOWING A FAIR AMOUNT OF RUN TO RUN
VARIABILITY WITH RESPECT TO THE DETAILS WITH THE FRONT/DEEP LAYER
TROUGH...THEY HAVE BEEN CONSISTENT IN DEPICTING UNSETTLED WEATHER
FROM LATE FRIDAY INTO SUNDAY. STILL TOO EARLY TO BE EXCEEDINGLY
CONFIDENT IN MODEL SOLUTIONS OR TO ISSUE ANY OUTLOOK PRODUCTS FOR
THIS POTENTIAL EVENT.

&&

.AVIATION...
VFR AND MODERATE TRADES PERSIST ACRS THE FA THIS AFTERNOON. ISOL
MVFR CIGS 025-030 EXP ALG WINDWARD SECTIONS AFT 26/04Z. TRADES MAY
INCREASE TONIGHT-TUESDAY AFTERNOON POSSIBLY REQUIRING AIRMET TANGO
FOR LLVL LEE TURB.

&&

.MARINE...
SURF IS EXPECTED TO RISE ALONG N AND W FACING SHORES TONIGHT AND
TUESDAY...APPROACHING BUT REMAINING BELOW ADVISORY LEVELS. OVERNIGHT
BUOY OBSERVATIONS WILL BE CLOSELY MONITORED IN CASE THE SWELL TURNS
OUT LARGER THAN EXPECTED. A POWERFUL LOW NOW CRANKING UP ABOUT 1800
MILES NW OF THE ISLANDS WILL HAVE STRONG WINDS POINTED AT THE
ISLANDS OVER THE NEXT COUPLE OF DAYS...GENERATING A SIGNIFICANT NW
SWELL THAT WILL BUILD THURSDAY AND PEAK FRIDAY. SOME UNCERTAINTY
REMAINS AS TO WHETHER OR NOT SURF HEIGHTS WILL REACH WARNING LEVELS
ALONG EXPOSED N AND W FACING SHORES...BUT SURF WILL BE LARGE AND
HAZARDOUS. ADDITIONAL DETAILS ARE CONTAINED IN THE RECENTLY UPDATED
SURF DISCUSSION...SRDHFO.

THE SMALL CRAFT ADVISORY /SCA/ FOR THE ALENUIHAHA CHANNEL HAS BEEN
EXPANDED THIS AFTERNOON TO INCLUDE ADDITIONAL WATERS AROUND MAUI AND
THE BIG ISLAND...AS TRADE WINDS ARE EXPECTED TO INCREASE TONIGHT AND
TUESDAY. WINDS WILL DIMINISH AND VEER TO THE SE FROM LATE TUESDAY
INTO THURSDAY...WITH SEA CONDITIONS EXPECTED TO REMAIN BELOW SCA
CRITERIA. THE NW SWELL ARRIVING THURSDAY AND FRIDAY IS EXPECTED
TO PUSH COMBINED SEAS OVER 10 FEET...LIKELY NECESSITATING A SCA IN
MARINE ZONES AROUND KAUAI AND OAHU...AND POSSIBLY ELSEWHERE.

&&

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

&&

DISCUSSION/MARINE...BIRCHARD
AVIATION...DEJESUS