Current Conditions
Temp0.8 C
RH12 %
WindSSW 8 mph
RoadClosed
Menu of Text Products for the Hawaiian Islands and the Tropical Pacific/Atlantic Oceans:
Narrow the Menu List
Select Time Limit: 12 hours | 24 hours | 48 hours | 72 hours | No time limit
Select Product Type: All | Routine Bulletins/FCSTS | Warnings/Watches/Advisories | HAWN Weather | Tropical | Marine | Aviation | Daily Obs | Special
Hawaiian Islands Synoptic Discussion and Guidance

420
FXHW60 PHFO 301332
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
330 AM HST TUE JUN 30 2015

.SYNOPSIS...
LIGHT TRADES WILL CONTINUE TO ALLOW FOR AFTERNOON SEA BREEZES AND
NIGHTTIME LAND BREEZES TO FORM DURING THE NEXT COUPLE OF DAYS. THIS
WILL BRING CLOUD COVER AND SHOWERS OVER LEEWARD AND INTERIOR AREAS
IN THE AFTERNOON AND EARLY EVENING HOURS. NIGHTS AND MORNINGS WILL
BE GENERALLY CLEAR...EXCEPT FOR A FEW LINGERING SHOWERS OVER
WINDWARD SECTIONS. INCREASING SHOWERS MAY OCCUR AROUND MID-WEEK OVER
THE BIG ISLAND AS A BATCH OF TROPICAL MOISTURE PASSES SOUTH OF THE
AREA. THE TRADES ARE EXPECTED TO RETURN BY THE END OF THE WORK WEEK
AND INTO THE HOLIDAY WEEKEND.

&&

.DISCUSSION...
WV SATELLITE IMAGERY SHOWS A WEAKENING UPPER TROUGH LOCATED ACROSS
THE ALOHA STATE...WHILE MODEL AND SATELLITE DATA SUGGEST THE
PRESENCE OF AN UPPER LEVEL SHORTWAVE TROUGH FAR NNW OF THE ISLANDS.
MEANWHILE...TWO SFC HIGH PRESSURE SYSTEMS ARE CENTERED FAR TO THE NE
AND TO THE NW OF THE MAIN HAWAIIAN ISLANDS WITH A WEAK SFC TROUGH
LOCATED IN THE MIDDLE. THIS SYNOPTIC SCENARIO WILL KEEP PRESSURE
GRADIENTS RATHER WEAK WITH THE TRADE WINDS REMAINING ON THE LIGHTER
SIDE. THUS...EXPECT AFTERNOON SEA BREEZES AND NIGHTTIME LAND BREEZES
TO DEVELOP AGAIN THIS AFTERNOON AND DURING THE NEXT COUPLE OF DAYS.
SHOWERS WILL BE ACTIVE IN THE AFTERNOON AND EARLY EVENING HOURS AS
SEA BREEZES PUSH INLAND...THEN GRADUALLY CLEARING OUT AFTER MIDNIGHT
WHEN LAND BREEZES DEVELOP. HOWEVER...THERE MIGHT BE ENOUGH
BACKGROUND FLOW LATE AT NIGHT TO KEEP SOME CLOUD BUILD-UPS AND
LINGERING SHOWERS OVER WINDWARD AREAS OF THE SMALLER ISLANDS. THE
12Z SOUNDINGS SUPPORT THE IDEA OF INCREASING OVERALL MOISTURE WITH
PWATS AROUND 1.25 INCHES...ALONG WITH WEAK OR COMPLETELY ERODED
INVERSIONS.

LATEST MIMIC AND MOISTURE ANALYSES MODEL DATA SHOW A LARGE AREA OF
ENHANCED TROPICAL MOISTURE JUST TO THE SSE OF THE BIG ISLAND WHICH
IS EXPECTED TO BRING AN INCREASE IN SHOWER COVERAGE TONIGHT AND
INTO WED...ESPECIALLY OVER THE BIG ISLAND AND MAUI.

FOR THE SECOND HALF OF THE WORK WEEK...MODELS ARE IN FAIR AGREEMENT
REGARDING A GRADUAL RETURN TO STRONGER TRADES AS THE SFC TROUGH TO
THE N OF THE ISLANDS MOVES E AND THE SFC HIGH PRESSURE INTENSIFIES.
ALOFT...MODELS WEAKEN THE PERSISTENT TROUGH OVER THE ISLANDS AND
ALLOW FOR A DRIER TREND TO ESTABLISH LATE IN THE WORK WEEK AND INTO
THE WEEKEND WITH SHOWERS SHIFTING BACK TO FAVOR WINDWARD AND MAUKA
AREAS.

&&

.AVIATION...
TODAY...LIGHT WINDS...GENERALLY FROM THE EAST TO SOUTHEAST...WILL
PERSIST ACROSS THE ISLAND CHAIN AND ADJACENT WATERS DUE TO A WEAK
SURFACE TROUGH NEAR AND JUST NORTH OF THE STATE. OVER THE ISLES
THEMSELVES...THE WINDS WILL BECOME SEA BREEZES DURING THE DAYTIME
HOURS AND LAND BREEZES AT NIGHT. EXPECT WIDESPREAD VFR CONDITIONS
MAINLY FROM THE LATE EVENING TO MID MORNING HOURS. AFTERNOON
CONVECTION WILL PRODUCE ISOL MVFR CIGS AND SHRA...ESPECIALLY OVER
THE MOUNTAIN SLOPES AND INTERIOR PARTS OF THE ISLANDS. THE AFTERNOON
CLOUDS WILL DISSIPATE AS THE EVENING TIME PROGRESSES.

&&

.MARINE...
SMALL CRAFT ADVISORY CONDITIONS ARE NOT EXPECTED THROUGH THE
WEEK...AND PERHAPS NOT UNTIL LATE IN THE WEEKEND. A SERIES OF SMALL
TO MODERATE SOUTH-SOUTHWEST SWELLS WILL CONTINUE THROUGH THE WEEK.
THE LIGHT BACKGROUND EAST TO SOUTHEAST FLOW WILL KEEP SHORT
PERIOD WIND SWELL BELOW TYPICAL SUMMERTIME HEIGHTS.

A SMALL NORTHWEST SWELL IS EXPECTED TO ARRIVE LATE WEDNESDAY
NIGHT...PEAK THURSDAY...AND SLOWLY DIMINISH FRIDAY.

&&

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

&&

$$

DISCUSSION/MARINE...REYNES
AVIATION...KINEL





Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office