Menu of Text Products for the Hawaiian Islands and the Tropical Pacific/Atlantic Oceans: Select a text product: 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 793 FXHW60 PHFO 200555 AFDHFO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 830 PM HST WED JUN 19 2013 .SYNOPSIS... LIGHT TO MODERATE TRADE WINDS WILL STRENGTHEN OVER THE WEEKEND...AND THEN DIMINISH INTO THE MIDDLE OF NEXT WEEK. RAINFALL ACROSS THE STATE WILL BE MAINLY LIGHT...AND LIMITED TO LEE SLOPES OF THE BIG ISLAND EACH AFTERNOON...AND WINDWARD SLOPES OF MOST ISLANDS ALL DAY. && .DISCUSSION... SURFACE OBSERVATIONS AROUND THE MAIN HAWAIIAN ISLANDS REPORTED LIGHT TO MODERATE TRADE WINDS. SOUNDING DATA SHOWED LITTLE MOMENTUM THROUGH THE DEPTH OF THE NEAR-SURFACE MIXED LAYER...AND PRESSURE TRENDS SUGGESTED A SLIGHT DECREASE IN WIND SPEED THROUGH THE SHORT RUN. RAINFALL ACROSS THE STATE WAS LIGHT OVERALL...WITH MOST MEASURABLE ACCUMULATION LIMITED TO WINDWARD KAUAI AND LEE SLOPES OF THE BIG ISLAND. SOUNDING MEASUREMENTS AND SATELLITE ESTIMATES OF PRECIPITABLE WATER SHOWED AN AIR MASS WITH FAIRLY TYPICAL HUMIDITY FOR THE SEASON. ALOFT...BROAD BUT WEAK RIDGING PREVAILED OVER THE EAST HALF OF THE ARCHIPELAGO...WHILE SHALLOW TROUGHING LANGUISHED OVER THE WEST HALF. GUIDANCE SOLIDLY AGREED THAT THE MAIN CHANGES THROUGH THE FORECAST PERIOD WILL CONSIST OF SHIFTS IN THE POSITION OF DEEP-LAYER RIDGING OVER THE STATE. THROUGH THIS COMING WEEKEND...THE RIDGE ALOFT WILL STRENGTHEN AND MIGRATE WEST...GRADUALLY INCREASING SUPPORT FOR THE SUBTROPICAL RIDGE AT THE SURFACE TO THE NORTH OF THE ISLANDS. THUS...BY AROUND FRIDAY NIGHT THE TRADE WINDS WILL START TO SPEED UP NOTICEABLY. BY SUNDAY NIGHT OR MONDAY...THE RIDGE ALOFT WILL BE STRONGER THAN EVER...BUT SHIFTED SO FAR NORTHWEST THAT TROUGHING FROM THE NORTHEAST WILL START TO ERODE THE SURFACE RIDGE INSTEAD... LEADING TO A GENERAL DECREASE IN WIND SPEEDS INTO THE MIDDLE OF NEXT WEEK. THROUGHOUT THE WHOLE PERIOD...STABILITY WILL REMAIN HIGH ENOUGH THAT MOST RAINFALL WILL RESULT FROM OROGRAPHIC FORCING ALONG WINDWARD SLOPES. ABUNDANT SUNSHINE ALSO WILL DRIVE SEA-BREEZE CUMULUS DEVELOPMENT OVER LEE SLOPES OF THE BIG ISLAND...THOUGH SUBSIDENCE AND A SHORTAGE OF MOISTURE WILL TEND TO LIMIT THIS ACTIVITY. && .AVIATION... EXPECT LITTLE SIGNIFICANT CHANGE IN AVIATION WEATHER ACROSS THE MAIN HAWAIIAN ISLANDS THROUGH THURSDAY MORNING. CONDITIONS WILL REMAIN MOSTLY VFR...EXCEPT FOR BRIEF PERIODS OF MVFR CEILINGS DUE TO LOW CLOUDS OVER SOME WINDWARD AND MAUKA AREAS...INCLUDING PHTO. && .MARINE... CONDITIONS WILL REMAIN CLOSE TO THE CRITERIA FOR A SMALL CRAFT ADVISORY OVER TYPICALLY WINDY WATERS AROUND THE BIG ISLAND AND MAUI THROUGH FRIDAY. THE ADVISORY LIKELY WILL BE NEEDED AS WIND SPEEDS INCREASE INTO THE WEEKEND. NO SIGNIFICANT SWELLS ARE IN STORE. MODERATE AND ROUGH SURF WILL PERSIST ALONG WINDWARD SHORES. SMALL BACKGROUND SOUTH SWELLS WILL HOLD FOR THE NEXT FEW DAYS...FOLLOWED BY A MODERATE SOUTHEAST SWELL FROM SUNDAY INTO EARLY NEXT WEEK. A MODERATE SOUTH SOUTHWEST SWELL IS POSSIBLE BY THE MIDDLE OF NEXT WEEK. NORTH-FACING SHORES SHOULD ALSO SEE A SMALL NORTHWEST SWELL MONDAY THROUGH WEDNESDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ AVIATION...HOUSTON REST...RYSHKO Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office This page is maintained voluntarily by the MKWC and the UHMET faculty, staff, and students. It was last modified on: Tue, Sep 21 2010 - 2314 UTC Send comments to: Ryan Lyman