High Surf in Hawaii, June 19 to 21, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST FRI JUN 19 2015

.SYNOPSIS...
HIGH PRESSURE NORTH OF THE ISLANDS WILL MAINTAIN LOCALLY BREEZY
TRADE WINDS INTO THE WEEKEND...WITH A SLIGHT DECREASE EXPECTED NEXT
WEEK. THE TRADES WILL KEEP LOW CLOUDS AND BRIEF SHOWERS FOCUSED
OVER WINDWARD AND MAUKA AREAS...MAINLY AT NIGHT AND IN THE MORNING.
AN INCREASE IN SHOWERS IS POSSIBLE FOR THE NORTHERN END OF THE STATE
SUNDAY AND EARLY NEXT WEEK.

&&

.DISCUSSION...
LOCALLY BREEZY TRADE WINDS WILL PERSIST FOR THE NEXT COUPLE OF DAYS.
A LOW LEVEL RIDGE EXTENDS BETWEEN A PAIR OF SURFACE HIGH PRESSURE
CENTERS 850 MILES NORTHWEST AND 1700 MILES NORTHEAST OF THE STATE.
THE RIDGE IS PARTIALLY DISRUPTED BY A WEAK FRONT STALLED 400 MILES
NORTH OF KAUAI...BUT THE PRESSURE GRADIENT OVER THE ISLANDS REMAINS
STRONG ENOUGH TO SUPPORT LOCALLY BREEZY TRADE WINDS. EXPECT LITTLE
CHANGE THROUGH FRIDAY WITH A SLIGHT INCREASE IN WINDS POSSIBLE NEAR
KAUAI AND OAHU ON SATURDAY AS THE HIGH CURRENTLY NORTHWEST OF THE
STATE SHIFTS EASTWARD AND STRENGTHENS.

LITTLE CHANGE IN THE RECENT RAINFALL PATTERN IS EXPECTED IN THE NEXT
COUPLE OF DAYS. MID LEVEL RIDGING WILL CONTINUE TO PRODUCE A
SOMEWHAT STRONG INVERSION BETWEEN 6000 AND 7000 FT...AND
PRECIPITABLE WATER VALUES JUST UPWIND OF THE STATE WILL PERSIST
RIGHT AROUND THE JUNE NORMAL OF ABOUT 1.3 INCHES. CLOUDS WITHIN THIS
FLOW CONTAIN A MIX OF STABLE STRATOCUMULUS AND SHOWER-BEARING
CUMULUS...WHICH BECOME MORE PREVALENT WEST OF 150W. UNDER THESE
CONDITIONS...EXPECT SHOWERS ALONG WINDWARD SLOPES TO BE SOMEWHAT
ACTIVE AT NIGHT AND IN THE MORNING. ASIDE FROM AFTERNOON CLOUDS AND
A FEW SHOWERS ON THE KONA SLOPES OF THE BIG ISLAND...LEEWARD AREAS
SHOULD BE RATHER DRY.

AN INCREASE IN SHOWERS IS POSSIBLE...MAINLY FOR KAUAI AND OAHU...
SUNDAY INTO EARLY NEXT WEEK ALONG WITH A SLIGHT DECREASE IN THE
TRADES. FORECAST MODELS HAVE BEEN CONSISTENTLY SHOWING REMNANT
MOISTURE FROM THE ABOVE MENTIONED DISSIPATED FRONT GETTING CAUGHT UP
IN THE TRADES AND MOVING OVER THE NORTHERN END OF THE STATE. TRADES
SHOULD DROP A NOTCH DURING THIS TIME AS THE HIGH NORTH OF THE STATE
IS WEAKENED BY A DEEPENING LOW OVER THE FAR NORTHERN PACIFIC.

&&

.AVIATION...
AIRMET TANGO REMAINS IN EFFECT FOR LOW-LEVEL TURBULENCE LEEWARD OF
THE HIGHER TERRAIN DUE TO THE BREEZY TRADE WINDS.

EXPECT VFR CONDITIONS TO PREVAIL OVER MOST AREAS. BRIEF PERIODS OF
MVFR CIG/VIS ARE POSSIBLE ALONG WINDWARD SLOPES... AND OVER THE
BIG ISLAND LEEWARD SLOPES IN THE AFTERNOON.

&&

.MARINE...
A SMALL CRAFT ADVISORY /SCA/ CONTINUES DUE TO LOCALLY STRONG TRADE
WINDS IN THE TYPICALLY WINDY WATERS AROUND THE BIG ISLAND AND MAUI.
THE SCA CURRENTLY RUNS THROUGH SATURDAY AFTERNOON AND MAY NEED TO BE
EXTENDED INTO SUNDAY. IN ADDITION...WINDS AROUND KAUAI COULD BRIEFLY
TOUCH SCA CRITERIA ON SATURDAY AS THE HIGH TO THE NORTHWEST OF THE
STATE EDGES CLOSER. A SLOW DECREASE IN TRADE WINDS IS EXPECTED
THROUGH NEXT WEEK...WITH TRADES AT BORDER LINE SCA LEVELS NEAR THE
BIG ISLAND AND MAUI THROUGH THE FIRST PART OF THE WORK WEEK.

A SMALL...MID-PERIOD SOUTHEAST SWELL WILL PERSIST THROUGH MUCH OF
THE WEEK...BUT THE MAIN SOURCE FOR SWELL ENERGY WILL BE A SOUTH
SOUTHWEST SWELL PRODUCED BY A SLOW MOVING STORM THAT SET UP
SOUTHEAST OF NEW ZEALAND A WEEK AGO. FORERUNNERS HAVE SHOWN UP
DURING THE PAST FEW HOURS AT THE BUOYS SOUTH OF THE STATE AND WILL
CONTINUE TO BUILD TODAY. WAVEWATCH III FORECASTS PEAK SWELL HEIGHTS
OF 3 FT ACROSS HAWAIIAN WATERS LATE SATURDAY AND SUNDAY...AND WITH
SWELLS OF UP TO 4 FT LOOKING INCREASINGLY LIKELY...SOUTH SHORE SURF
COULD TOP THE 8 FOOT THRESHOLD. THE DECLINING SWELL WILL LINGER
THROUGH MUCH OF THE UPCOMING WORK WEEK.

&&

.FIRE WEATHER...
THE KEETCH-BYRAM DROUGHT INDEX /KBDI/...ONE OF THE PARAMETERS USED
TO ASSESS CRITICAL FIRE WEATHER CONDITIONS...WILL REMAIN HIGHER THAN
SEASONAL NORMAL FOR QUITE SOME TIME. THE OTHER FACTORS...SUSTAINED
WINDS AND RELATIVE HUMIDITY VALUES...ARE EXPECTED TO BE CLOSE BUT
JUST SHY OF CRITERIA EACH AFTERNOON THROUGH SATURDAY.

&&

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

&&

DISCUSSION/MARINE/FIRE WX...WROE
AVIATION...MORRISON