240
FXHW60 PHFO 140627
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
827 PM HST SUN APR 13 2025
SYNOPSIS
BREEZY TRADE WINDS WILL CONTINUE THROUGH TUESDAY, WITH PASSING
CLOUDS AND SHOWERS FAVORING WINDWARD AND MAUKA AREAS. LIGHTER
WINDS ARE EXPECTED BY THE MIDDLE OF THE WEEK WITH FEWER WINDWARD
SHOWERS AND A GREATER CHANCE FOR AFTERNOON INTERIOR SHOWERS EACH
AFTERNOON THROUGH THE WEEKEND.
DISCUSSION
HIGH PRESSURE CENTERED TO THE FAR NORTHEAST OF THE STATE WILL
MAINTAIN BREEZY TRADE WINDS ACROSS THE REGION THROUGH TUESDAY.
THIS EVENING'S RADAR AND INFRARED SATELLITE IMAGERY SHOW ISOLATED
SHOWERS MOVING INTO WINDWARD AREAS ON THE BREEZY TRADES. A POCKET
OF DRIER AIR IS CURRENTLY MOVING ACROSS OAHU AND KAUAI, BUT PLENTY
OF LOW LEVEL MOISTURE CAN BE SEEN UPSTREAM AND WILL MOVE ACROSS
THE STATE OVERNIGHT, INCREASING SHOWER COVERAGE - MAINLY ACROSS
WINDWARD AREAS. IN ADDITION, A WEAK UPPER LEVEL LOW CAN BE SEEN
MOVING OVER THE STATE FROM THE WEST IN WATER VAPOR IMAGERY. THIS
AFTERNOON'S UPPER AIR SOUNDING FROM LIHUE ATTESTS TO THE WEAK
INSTABILITY THIS FEATURE IS BRINGING TO THE AREA AS LAPSE RATES
HAVE STEEPENED SLIGHTLY. MODEL GUIDANCE SHOWS THAT THIS UPPER LOW
WILL GRADUALLY MOVE ACROSS THE STATE THROUGH TUESDAY CONTRIBUTING
TO A SLOW EASTWARD SPREADING OF WEAK INSTABILITY, WHICH MAY ALLOW
FOR THE ENHANCEMENT OF WINDWARD SHOWERS MOVING IN ON THE BREEZY
TRADES. SOME OF THESE SHOWERS COULD DELIVER BRIEF DOWNPOURS THAT
WILL OCCASIONALLY SPILL OVER INTO LEEWARD AREAS.
MID-LEVEL RIDGING WILL BRIEFLY BUILD OVERHEAD LATE TUESDAY INTO
EARLY WEDNESDAY IN ADVANCE OF A MID-LEVEL SHORTWAVE TROUGH THAT
WILL DIVE SOUTHEAST ACROSS THE CENTRAL PACIFIC AND BEGIN TO EDGE
OVER HAWAII BY WEDNESDAY NIGHT. AT THE SURFACE, A STRONG LOW
PRESSURE SYSTEM TO THE FAR NORTH WILL DISPLACE THE RIDGE THAT'S
BEEN ANCHORED TO OUR NORTHEAST TO BRING IT CLOSER TO, OR OVER,
THE ISLAND CHAIN. THE PROXIMITY OF THIS SURFACE RIDGE AND THE
APPROACH OF A FRONT/TROUGH FROM THE NORTHWEST WILL BRING LIGHTER
SOUTHEAST WINDS ACROSS THE AREA, ALLOWING LAND AND SEA BREEZES TO
EXPAND IN COVERAGE BEGINNING ON WEDNESDAY. THE SHORTWAVE TROUGH
WILL DIVE DOWN THE ISLAND CHAIN THROUGH THE WEEKEND AND OPEN UP
AND WEAKEN HEADING INTO EARLY NEXT WEEK. THE GREATEST INSTABILITY
ASSOCIATED WITH THE ORIENTATION OF THE SHORTWAVE TROUGH AND THE
COOLEST TEMPERATURES ALOFT, AND THE DEEPEST ATMOSPHERIC MOISTURE
ALL SEEM TO LINE UP BEST ON THURSDAY AND FRIDAY. AS SUCH, THE
POTENTIAL FOR HEAVY SHOWERS WILL BE GREATEST ON THURSDAY AND
FRIDAY AFTERNOONS WITH THE SEA BREEZE ACTIVITY. LIGHT WINDS WILL
CONTINUE INTO THE WEEKEND AS THE MID-LEVEL SHORTWAVE WEAKENS
RESULTING IN EITHER A LAND/SEA BREEZE PATTERN WITH MORE MUTED
DIURNAL CONVECTION OR A HYBRID SEA BREEZE PATTERN WHICH WILL TEND
TO FOCUS SHOWERS OVER WESTERN SLOPES OF EACH ISLAND.
AVIATION
BREEZY TRADE WINDS WILL STEER BANDS OF CLOUDS AND LIGHT SHOWERS
OFF THE PACIFIC TOWARDS THE ISLANDS. SHOWERS WILL BE MOST ACTIVE
IN THE LATE NIGHT AND MORNING HOURS AND FAVOR WINDWARD SLOPES AND
COASTS.
AIRMET TANGO REMAINS IN EFFECT FOR OCCASIONAL MODERATE TURBULENCE
BELOW 8000 FEET OVER AND ALONG THE LEE SIDE OF ALL HAWAIIAN
ISLANDS AND WILL LIKELY REMAIN NECESSARY THROUGH AT LEAST MONDAY
AFTERNOON.
AIRMET TANGO IS ALSO POSTED FOR JET STREAM TURBULENCE
OVER HAWAII BETWEEN FL280 AND FL380. THIS SECOND AIRMET WILL
LIKELY BE CANCELLED LATER THIS EVENING ONCE THE ASSOCIATED PEAK IN
THE JET STREAM SHIFTS NORTHEASTWARD.
MARINE
HIGH PRESSURE NORTHEAST OF THE STATE WILL MAINTAIN MODERATE TO
STRONG TRADES THROUGH MONDAY NIGHT. A SMALL CRAFT ADVISORY (SCA)
REMAINS IN EFFECT FOR THE TYPICALLY WINDY WATERS AROUND MAUI AND
THE BIG ISLAND THROUGH 6 PM MONDAY, BUT THIS WILL LIKELY NEED TO
BE EXTENDED THROUGH MONDAY NIGHT, AND POSSIBLY INTO TUESDAY FOR
SOME ZONES ON THE BIG ISLAND FAVORED IN AN EAST-SOUTHEASTERLY
FLOW. THE TRADES WILL GRADUALLY EASE TUESDAY AND TUESDAY NIGHT,
THEN BECOME FURTHER DISRUPTED WEDNESDAY THROUGH FRIDAY AS A FRONT
APPROACHES, STALLS OUT, AND DISSIPATES NORTHWEST OF THE STATE.
WINDS WILL BECOME LIGHT AND VARIABLE DURING THE MID TO LATE WEEK
TIME FRAME OVER THE WESTERN WATERS, WHILE WINDS OVER THE EASTERN
END OF THE STATE SHIFT OUT OF THE EAST-SOUTHEAST AT LIGHT TO
MODERATE SPEEDS.
EAST SHORE SURF WILL REMAIN AT OR JUST ABOVE AVERAGE THROUGH
TUESDAY, AND WILL BE RATHER ROUGH DUE TO THE STRONG TRADES,
PARTICULARLY THROUGH MONDAY. AS THE TRADES DIMINISH DURING THE
SECOND HALF OF THE WEEK, SURF ALONG EAST FACING SHORES WILL DROP
BELOW NORMAL.
A SMALL TO MODERATE SIZED NORTHWEST SWELL WILL GIVE A BOOST TO
SURF ALONG NORTH AND WEST FACING SHORES MONDAY AND TUESDAY,
FOLLOWED BY A DECLINE WEDNESDAY AND THURSDAY. A NEW MODERATE-
SIZED NORTH-NORTHWEST SWELL WILL ARRIVE THURSDAY, POTENTIALLY
BRINGING ADVISORY LEVEL SURF TO NORTH AND WEST FACING SHORES
THURSDAY NIGHT AND FRIDAY, THEN SLOWLY LOWERING NEXT WEEKEND.
SURF ALONG SOUTH FACING SHORES WILL REMAIN SMALL AND MOSTLY AT
BACKGROUND LEVELS THROUGH THURSDAY. A SERIES OF SMALL OVERLAPPING
SOUTH SWELLS COULD BRING SURF UP TO SEASONAL LEVELS FRIDAY
THROUGH NEXT WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST MONDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...FARRIS
AVIATION...BEDAL
MARINE...JELSEMA
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