Drought in Hawaii, June 23 to 30, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE JUN 23 2015

.SYNOPSIS...
LIGHT TO MODERATE TRADE WINDS WILL DIMINISH SLOWLY INTO THE WEEKEND.
CLOUDS AND SHOWERS WILL CONTINUE TO FAVOR WINDWARD SLOPES ALL DAY...
BUT AFTERNOON BUILDUPS MAY INCREASE WITH TIME.

&&

.DISCUSSION...
SURFACE OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS STILL REPORTED
LIGHT TO MODERATE TRADE WINDS PREVAILING. THE INVERSION ROSE FURTHER
DURING THE PAST SIX HOURS...AND A PLUME OF REMNANT MOISTURE FROM A
DISSIPATED FRONT EXTENDED FAR UPWIND OF THE STATE...THOUGH THE SOUTH
EDGE OF THIS MOIST AIR MASS CUT ACROSS THE BIG ISLAND...LEAVING
PARTS OF IT IN DRIER AIR.

MARINE SHOWER ACTIVITY INCREASED OVERNIGHT...FOLLOWING DIURNAL
TRENDS...AND THE TRADE WINDS REMAINED STRONG ENOUGH TO MOVE MANY OF
THESE SHOWERS ASHORE ALONG WINDWARD SLOPES. ACCUMULATION PUSHED THE
LIMITS OF WHAT COULD BE CONSIDERED LIGHT PRECIPITATION IN PLACES...
THOUGH AVERAGING OVER WINDWARD SLOPES ACROSS THE STATE YIELDED
RESULTS WELL WITHIN CLIMATIC NORMS. LAND BREEZES DID NOT BECOME
IMPORTANT OUTSIDE OF VERY LIMITED AREAS.

A SOLID MID-LEVEL RIDGE PREVAILED OVER AND TO THE WEST OF THE STATE.
GUIDANCE STILL AGREED IN PREDICTING A TROUGH TO EXPAND SOUTH OUT OF
THE MAIN STORM TRACK ALONG THE EAST EDGE OF THIS RIDGE GRADUALLY
THROUGH THE WEEK. HOWEVER...RECENT RUNS CONTINUED TO SHOW THE TROUGH
DIGGING MORE SLOWLY...AND REMAINING SLIGHTLY FURTHER NORTH...THAN
EXPECTED EARLIER. ALTHOUGH THE RIDGE STILL WILL SHIFT WEST AND
WEAKEN SIGNIFICANTLY BY THURSDAY EVENING OR FRIDAY...IT SHOULD
RETAIN SOME INFLUENCE OVER LOCAL WEATHER.

AT THE SURFACE...THE SUBTROPICAL RIDGE WILL WEAKEN AS SUPPORT FROM
ALOFT DIMINISHES...SO TRADE WIND SPEEDS WILL DECLINE. HOWEVER...
TRADE WINDS SHOULD PERSIST THROUGH THE FORECAST PERIOD...AND WILL
BE LESS LIKELY TO PICK UP ANY SOUTHERLY COMPONENT IN DIRECTION
THROUGH THE WEEKEND AT LEAST. IN GENERAL...IT NOW APPEARED THAT
DEPARTURES FROM CLIMATOLOGY WILL BE LESS THAN EXPECTED EARLIER.
HOWEVER...SEA BREEZES STILL MAY BECOME LOCALLY IMPORTANT LATE IN
THE WEEK.

GUIDANCE SUGGESTED THAT A TROPICAL WAVE OR DISTURBANCE MAY PASS
SOUTH OF THE STATE EARLY NEXT WEEK. IF SO...THEN WIND SPEEDS SHOULD
INCREASE AGAIN...AND WIND DIRECTION FINALLY MAY TURN MORE
SOUTHEASTERLY...DEPENDING ON HOW CLOSE THE FEATURE TO THE SOUTH
APPROACHES AS IT PASSES.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS MOST AREAS THROUGH TODAY AS
MODERATE TRADE WINDS CONTINUE OVER THE ISLANDS. BRIEF PERIODS OF
MVFR CEILINGS AND/OR VISIBILITIES CAN BE EXPECTED MAINLY ACROSS
WINDWARD AND MAUKA SECTIONS OF THE SMALLER ISLANDS AS PASSING TRADE
SHOWERS MOVE THROUGH.

AIRMET SIERRA FOR MOUNTAIN OBSCURATION HAS BEEN POSTED FOR WINDWARD
SECTIONS OF THE BIG ISLAND...WHERE MORE WIDESPREAD MVFR IN SHOWERS
AND CLOUDS WILL BE POSSIBLE INTO THIS MORNING. CONDITIONS SHOULD
IMPROVE BY LATE MORNING.

&&

.MARINE...
WINDS WILL DIMINISH SLOWLY THIS WEEK...SO CONDITIONS ARE NOT
EXPECTED TO REACH THE THRESHOLD FOR A SMALL CRAFT ADVISORY INTO THE
WEEKEND.

SLOWLY DECLINING SURF ALONG SOUTH FACING SHORES WILL LINGER
THROUGH AT LEAST MIDWEEK...FOLLOWED BY SOME SMALL REINFORCING SWELL
OVER THE SECOND HALF OF THE WEEK. ALSO...A SMALLER SOUTHEAST SWELL
WILL DECLINE INTO THE WEEK.

&&

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

&&

DISCUSSION AND MARINE...RYSHKO
AVIATION...JACOBSON