Wildfire in Hawaii, July 20 to 23, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SAT JUL 20 2013

.SYNOPSIS...
LIGHT TO LOCALLY MODERATE TRADE WINDS WILL PERSIST ACROSS THE ALOHA
STATE FOR THE NEXT FEW DAYS. MOISTURE MOVING UP ACROSS THE ISLAND
CHAIN FROM THE SOUTHEAST IS EXPECTED TO CAUSE AN INCREASE IN SHOWERS
FOR WINDWARD BIG ISLAND BEGINNING SUNDAY AFTERNOON AND POSSIBLY FOR
SOME OTHER AREAS EARLY NEXT WEEK. SHOWERS WILL MAINLY FAVOR WINDWARD
AND MAUKA AREAS. HIGH PRESSURE WILL BUILD BACK IN NORTHEAST OF THE
STATE AROUND THE MIDDLE OF NEXT WEEK WITH TRADE WINDS INCREASING.

&&

.DISCUSSION...
AN AREA OF HIGH PRESSURE LIES FAR TO THE NORTH OF THE STATE.
NORMALLY A HIGH IN THIS POSITION WOULD PLACE THE ISLANDS IN A
MODERATE TO FRESH TRADE WIND ENVIRONMENT. HOWEVER A WEAK AREA OF LOW
PRESSURE SEEN MOVING WESTWARD ON SATELLITE IMAGERY LIES BETWEEN THE
HIGH CENTER AND THE MAIN HAWAIIAN ISLANDS. THIS HAS WEAKENED THE
PRESSURE GRADIENT OVER THE AREA RESULTING IN LIGHT TO LOCALLY
MODERATE TRADE WINDS.

IN THE MEANTIME A NORTHEAST THROUGH SOUTHWEST ORIENTED UPPER LEVEL
TROUGH LIES ACROSS THE AREA. THIS HAS DESTABILIZED THE ATMOSPHERE A
BIT AS EVIDENT BY THE 12Z SOUNDINGS. HOWEVER THE ATMOSPHERE IN THE
ISLAND VICINITY IS RATHER DRY SO ONLY A FEW SHOWERS ARE SEEN ON
RADAR IMAGERY MAINLY OVER THE WATERS NORTH OF MAUI COUNTY.

SATELLITE IMAGERY ALSO SHOWS AN AREA OF DISTURBED WEATHER ASSOCIATED
WITH A WEAK LOW LEVEL TROUGH SOUTHEAST OF THE BIG ISLAND. MUCH
HIGHER PRECIPITABLE WATER VALUES ARE EVIDENT WITH THIS FEATURE. THE
LEADING EDGE IS EXPECTED TO REACH THE BIG ISLAND OVERNIGHT TONIGHT
WITH THE BULK OF THE MOISTURE REACHING THE BIG ISLAND SUNDAY NIGHT.
AS THIS MOISTURE REACHES THE STATE SHOWER ACTIVITY WILL LIKELY PICK
UP ESPECIALLY FOR EAST SECTIONS OF THE BIG ISLAND AND POSSIBLY EAST
MAUI AS WELL.

HOW THIS MOISTURE AFFECTS THE REST OF THE STATE IS NOT QUITE CLEAR
YET. THE VAST MAJORITY OF THE MOISTURE WILL LIKELY PASS BY JUST
SOUTH OF THE STATE. WE WILL LIKELY SEE AN INCREASE IN WINDWARD AND
MAUKA SHOWERS OVER THE SMALLER ISLANDS MONDAY NIGHT INTO TUESDAY AS
THIS MOISTURE MOVE ACROSS THE AREA.

AS WE HEAD TOWARD THE MIDDLE AND LATTER PART OF NEXT WEEK HIGH
PRESSURE WILL BEGIN TO BUILD BACK IN TO THE NORTHEAST OF THE STATE
WITH TRADE WINDS PICKING UP TO MODERATE TO FRESH LEVELS. PASSING
SHOWERS WILL CONTINUE TO FAVOR WINDWARD AND MAUKA AREAS THOUGH
RIDGING BUILDING IN ALOFT WILL KEEP RAINFALL AMOUNTS ON THE LIGHT
SIDE.

&&

.MARINE...
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW THE SMALL CRAFT ADVISORY
LEVELS THROUGH TUESDAY. TRADE WINDS ARE FORECAST TO INCREASE ENOUGH
TO REQUIRE A SMALL CRAFT ADVISORY IN THE TYPICALLY WINDY WATERS
AROUND MAUI COUNTY AND THE BIG ISLAND STARTING WEDNESDAY.

THERE WILL BE A SERIES OF SMALL SOUTH SWELLS FOR THE REST OF THE
WEEKEND AND ON THROUGH NEXT WEEK WITH SURF HEIGHTS REMAINING BELOW
ADVISORY LEVELS. NO OTHER SIGNIFICANT SWELLS ARE EXPECTED.

&&

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

&&

BURKE