013
FXHW60 PHFO 151308
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
308 AM HST TUE APR 15 2025
SYNOPSIS
MODERATE TRADE WINDS WILL PREVAIL TODAY, WITH SHOWERS FAVORING
WINDWARD AND MAUKA AREAS. THE TRADES WILL EASE TONIGHT, WITH A
CONVECTIVE SHOWER PATTERN THEN DEVELOPING WEDNESDAY AND
CONTINUING THROUGH FRIDAY. A DISTURBANCE ALOFT MOVING OVER THE
ISLANDS COULD BRING SOME HEAVIER SHOWERS AND EVEN A FEW
THUNDERSTORMS AS IT SLOWLY SHIFTS EASTWARD ACROSS THE STATE DURING
THIS TIME. A RETURN TO A MORE TYPICAL TRADE WIND REGIME ALONG
WITH A GRADUAL INCREASE IN TRADE WIND SPEEDS WILL BE POSSIBLE OVER
THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
CURRENTLY AT THE SURFACE, A COLD FRONT IS LOCATED AROUND 900
MILES WEST-NORTHWEST OF KAUAI, WHILE A 1028 MB HIGH IS CENTERED
AROUND 1200 MILES NORTHEAST OF HONOLULU. THE RESULTING GRADIENT IS
PRODUCING MODERATE TRADES ACROSS THE ISLAND CHAIN EARLY THIS
MORNING. INFRARED SATELLITE IMAGERY SHOWS MOSTLY CLOUDY CONDITIONS
IN MOST WINDWARD AREAS, AND CLEAR TO PARTLY CLOUDY SKIES IN MOST
LEEWARD LOCALES. RADAR IMAGERY SHOWS SCATTERED SHOWERS MOVING
INTO WINDWARD AREAS, WITH A FEW SHOWERS REACHING LEEWARD
COMMUNITIES AT TIMES. MAIN SHORT TERM FOCUS REVOLVES AROUND TRADE
WIND TRENDS AND RAIN CHANCES.
THE RIDGE TO THE NORTH OF THE ISLANDS WILL GRADUALLY WEAKEN AND
ERODE DURING THE NEXT COUPLE DAYS AS A COLD FRONT APPROACHES FROM
THE NORTHWEST. MODERATE TRADE WINDS SHOULD HOLD IN PLACE TODAY,
BEFORE EASING TONIGHT. THE TRADES WILL BECOME DISRUPTED WEDNESDAY,
WITH SEA BREEZES COMMON OVER THE WESTERN ISLANDS, WHILE THE
TRADES SHIFT EAST-SOUTHEASTERLY AT LIGHT TO MODERATE SPEEDS OVER
THE EASTERN END OF THE STATE. THE FRONT WILL STALL OUT NORTHWEST
OF THE AREA THURSDAY AND FRIDAY, WITH BROAD TROUGHING IN PLACE
ACROSS THE ISLAND CHAIN. LAND AND SEA BREEZES WILL REMAIN COMMON
DURING THIS TIME, WITH BACKGROUND LIGHT EAST-SOUTHEAST WINDS
CONFINED TO AREAS AROUND THE BIG ISLAND. THE TROUGH APPEARS TO
DAMPEN OUT OVER THE WEEKEND, ALLOWING A GRADUAL RETURN AND
STRENGTHENING OF THE TRADES WHICH WILL CONTINUE INTO EARLY NEXT
WEEK.
AS FOR THE REMAINING WEATHER DETAILS, A FAIRLY TYPICAL TRADE WIND
SHOWER PATTERN WILL PREVAIL TODAY AND TONIGHT, WITH SHOWERS
FAVORING WINDWARD SLOPES AND COASTS. A SLIGHT EASING OF THE TRADES
COULD ALLOW FOR AN INCREASE IN LEEWARD SHOWERS THIS AFTERNOON
HOWEVER, WITH MOST OF THESE SHOWERS FIZZLING OUT QUICKLY IN THE
EVENING. A TRANSITION TO A CONVECTIVE PATTERN IS EXPECTED
WEDNESDAY THROUGH FRIDAY, WITH SHOWERS FAVORING THE ISLAND
INTERIORS DURING THE AFTERNOON AND EVENING HOURS, AND AREAS NEAR
THE COAST AT NIGHT. AN UPPER LEVEL TROUGH WILL MOVE SLOWLY
EASTWARD ACROSS THE STATE WEDNESDAY NIGHT THROUGH FRIDAY, WITH 500
MB TEMPERATURES LOWERING TO AROUND -12 TO -13C AND PRECIPITABLE
WATER VALUES INCREASING TO AROUND 1.5 INCHES. THIS WILL LIKELY
RESULT IN SOME HEAVIER SHOWERS, PARTICULARLY DURING THE AFTERNOON
AND EVENING HOURS. ISOLATED THUNDERSTORMS WILL ALSO BE POSSIBLE
AS THE COLD POOL ALOFT MOVES EASTWARD ACROSS THE STATE. A MORE
TYPICAL TRADE WIND PATTERN MAY SLOWLY RETURN OVER THE WEEKEND INTO
EARLY NEXT WEEK.
AVIATION
MODERATE TRADE WINDS WILL GRADUALLY EASE TONIGHT INTO WEDNESDAY
AND USHER IN CLOUDS AND SHOWERS TO WINDWARD COASTS AND SLOPES.
HOWEVER, WINDS MAY BEGIN TO BE LIGHT ENOUGH TO SEE SOME SEA BREEZE
DEVELOPMENT THAT WOULD BRING CLOUDS AND A FEW SHOWERS TO LEEWARD
AREAS, PARTICULARLY OVER LEEWARD SLOPES OF THE BIG ISLAND. IN
ADDITION, AS THE STEERING FLOW SHIFTS TO BECOME MORE
SOUTHEASTERLY, CONVERGENT BOUNDARIES MAY BE ANOTHER SOURCE OF
CLOUDS AND SHOWERS TO LEEWARD AREAS OF SOME OF THE SMALLER ISLANDS
AS WELL. MVFR CONDITIONS WILL BE POSSIBLE IN ANY SHOWERS, BUT
OVERALL, VFR CONDITIONS WILL PREVAIL.
MARINE
FRESH TO STRONG EASTERLY TRADE WINDS WILL GRADUALLY EASE AND
SHIFT OUT OF THE EAST-SOUTHEAST LATER TODAY THROUGH THE SECOND
HALF OF THE WEEK AS A FRONT APPROACHES AND STALLS NORTHWEST OF THE
STATE. OVER THE WESTERN END OF THE ISLANDS, THE WEAKENING WINDS
WILL ALLOW A LAND AND SEA BREEZE PATTERN TO DEVELOP. FOR THE
EASTERN END OF THE STATE, MODERATE TO FRESH EAST TO SOUTHEAST
BREEZES, WITH LOCALIZED STRONG POCKETS, WILL LIKELY PERSIST,
PARTICULARLY AROUND THE BIG ISLAND. AS A RESULT, THE SMALL CRAFT
ADVISORY HAS BEEN EXTENDED THROUGH THIS AFTERNOON FOR WATERS
SURROUNDING THE BIG ISLAND. A RETURN TO MODERATE TO FRESH EASTERLY
TRADES IS POSSIBLE BY THE WEEKEND AS THE RIDGE REESTABLISHES TO
THE NORTH.
SURF ALONG EXPOSED NORTH AND WEST FACING SHORES WILL STEADILY
LOWER THROUGH MIDWEEK AS A MEDIUM-PERIOD NORTHWEST SWELL EASES.
OBSERVATIONS AT OFFSHORE BUOYS TO THE NORTHWEST REFLECT THIS
DOWNWARD TREND, WITH PEAK ENERGY SHIFTING INTO THE 10-12 SECOND
BANDS THIS MORNING. AN UPWARD TREND IS EXPECTED LATE THURSDAY AS
A FRESH NORTH-NORTHWEST ARRIVES AND BUILDS DOWN THE ISLAND CHAIN.
SURF MAY NEAR THE ADVISORY LEVELS FOR EXPOSED NORTH AND WEST
FACING SHORES THURSDAY NIGHT INTO FRIDAY AS THIS SWELL PEAKS. A
DOWNWARD TREND IS THEN EXPECTED OVER THE WEEKEND.
SURF ALONG EAST FACING SHORES WILL TREND DOWN THROUGH THE WEEK AS
THE TRADES EASE AND SHIFT OUT OF THE EAST-SOUTHEAST.
SURF ALONG SOUTH FACING SHORES WILL REMAIN SMALL THROUGH THE WEEK,
WITH MAINLY OVERLAPPING BACKGROUND SOUTH SWELLS MOVING THROUGH.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR ALENUIHAHA
CHANNEL-BIG ISLAND WINDWARD WATERS-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...JELSEMA
AVIATION...FARRIS
MARINE...GIBBS
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