770
FXHW60 PHFO 151840
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
840 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
AT THE SURFACE, A 1025 MB SURFACE HIGH IS CENTERED FAR NORTHEAST
OF HAWAII DRIVING MODERATE TRADE WINDS ACROSS THE AREA. AN
APPROACHING COLD FRONT IS LOCATED AROUND 700 MILES NORTHWEST OF
KAUAI, WHILE AN APPROACHING WEAK TROUGH IS LOCATED 550 MILES EAST
OF THE BIG ISLAND. A TROUGH ALOFT IS CENTERED JUST NORTHEAST OF
THE ISLAND CHAIN AND MOVING EASTWARD AWAY FROM THE AREA. VISIBLE
SATELLITE AND RADAR SHOW A BAND OF LOW CLOUDS AND SHOWERS TRACKING
WESTWARD WITH THE TRADE WIND FLOW IMPACTING WINDWARD SIDES OF
OAHU, MOLOKAI AND MAUI THIS MORNING.
EXPECTING A CONTINUED WESTWARD PROGRESSION OF THE CLOUDS AND
SHOWERS THROUGH THE DAY LIKELY IMPACTING ALL SMALLER ISLANDS BY
THIS AFTERNOON THROUGH TONIGHT. SOME DISSIPATION OF THIS BAND
WILL OCCUR DURING THE DIURNAL MINIMUM THROUGH THE MIDDLE OF THE
DAY, BUT WILL FILL IN AGAIN BY LATE AFTERNOON AND EVENING. WINDS
WILL TAPER OFF AND VEER SOUTHEASTERLY TONIGHT AS THE FRONT AND
TROUGH CONVERGE ON THE ISLANDS. LAND BREEZES WILL KEEP MOST OF THE
ASSOCIATED CLOUDS AND SHOWERS WITH BOTH FEATURES OFFSHORE, BUT AS
SEA BREEZES BUILD IN DURING THE DAY WEDNESDAY, CLOUDS AND SHOWERS
WILL FOCUS OVER THE ISLANDS.
AN UPPER TROUGH WILL DIG SOUTHEASTERLY ACROSS THE ISLANDS LATE
WEDNESDAY NIGHT THROUGH FRIDAY. THE FRONT WILL MERGE WITH THE
SURFACE TROUGH CREATING A POOL OF LOW LEVEL MOISTURE OVER THE
STATE. 500 MB TEMPERATURES WILL LOWER TO AROUND -12 TO -13C AND
PRECIPITABLE WATER VALUES INCREASING TO AROUND 1.5 INCHES ON
THURSDAY. THIS WILL LIKELY RESULT IN SOME HEAVIER SHOWERS AND A
SLIGHT CHANCE OF THUNDERSTORMS THURSDAY AND FRIDAY (MORE OF THE
FOCUS WILL BE ON BIG ISLAND FRIDAY). POSSIBLE MINOR PONDING/FLOODING
RESULTING FROM THIS RAINFALL, BUT HOLDING OFF WITH A FLOOD WATCH
FOR NOW GIVEN THE BRIEF WINDOW OF UPPER LEVEL FORCING. THE UPPER
TROUGH WILL WEAKEN AND SLIDE EAST OF THE STATE BY LATE FRIDAY
RETURNING TO MORE A MORE STABLE ATMOSPHERE.
LIGHT TO MODERATE TRADE WINDS WILL GRADUALLY NOSE IN OVER THE
WEEKEND, WITH LIKELY WETTER-THAN-NORMAL WINDWARD AND MAUKA SHOWERS
BEFORE THE AREA OF MOISTURE IS CLEARED TO THE WEST. A MORE
TYPICAL TRADE WIND PATTERN MAY SLOWLY RETURN OVER THE WEEKEND INTO
EARLY NEXT WEEK.
AVIATION
MODERATE TRADES WILL GRADUALLY EASE INTO WEDNESDAY AND USHER IN
SHRA AND LOW CIGS TO WINDWARD AND MAUKA LOCATIONS. HOWEVER, WINDS
MAY BEGIN TO BE LIGHT ENOUGH TO SEE SOME SEA BREEZE DEVELOPMENT
THAT WOULD BRING SOME ISOL SHRA TO LEEWARD AREAS. MVFR CONDS WILL
BE POSSIBLE IN ANY SHRA, BUT VFR SHOULD PREVAIL.
NO AIRMETS IN EFFECT.
MARINE
TRADE WINDS WILL STEADILY DECLINE DURING THE NEXT 24 HOURS AS A
AN ADVANCING FRONT WEAKENS THE SURFACE RIDGE NORTH OF THE STATE. A
SMALL CRAFT ADVISORY (SCA) REMAINS IN EFFECT THROUGH THE AFTERNOON
FOR WATERS AROUND THE BIG ISLAND, WHILE TRADES REMAIN IN THE
MODERATE TO LOCALLY FRESH RANGE ELSEWHERE. BY WEDNESDAY MORNING,
GENTLE TO MODERATE EAST TO SOUTHEASTERLY WINDS WILL PREVAIL, WITH
A BRIEF PERIOD OF VARIABLE WINDS POSSIBLE AROUND KAUAI AND OAHU
WEDNESDAY AFTERNOON AND EVENING. GENTLE TO LOCALLY FRESH EAST TO
EAST-SOUTHEAST TRADE WINDS WILL DOMINATE THURSDAY AND FRIDAY, AND
A SLIGHT INCREASE IN WINDS MAY REQUIRE THE SCA TO BE REISSUED
AROUND THE BIG ISLAND AND MAUI DURING THE WEEKEND.
SURF ALONG EXPOSED NORTH AND WEST FACING SHORES WILL STEADILY
LOWER THROUGH WEDNESDAY AS A SMALL NORTHWEST SWELL EASES.
THE NOAA BUOYS NORTHWEST OF KAUAI REFLECT THIS DOWNWARD TREND,
WITH PEAK ENERGY SHIFTING INTO THE 10-12 SECOND BANDS THIS
MORNING. A MEDIUM PERIOD NORTH-NORTHWEST SWELL WILL BUILD THURSDAY
AND WILL PUSH SURF NEAR HIGH SURF ADVISORY LEVELS DURING THE PEAK
THURSDAY NIGHT AND EARLY FRIDAY. THIS SWELL WILL STEADILY DECLINE
AND SHIFT OUT OF THE NORTH LATER FRIDAY AND THE WEEKEND.
SURF ALONG EAST FACING SHORES WILL TREND DOWN OVER THE NEXT DAY OR
SO AS THE TRADES EASE. EAST SHORE SURF WILL REMAIN BELOW APRIL
AVERAGE THROUGH AT LEAST SATURDAY AND WILL LIKELY RISE TO AROUND
AVERAGE ON SUNDAY.
SURF ALONG SOUTH FACING SHORES WILL REMAIN SMALL THROUGH MOST OF
THE WEEK, WITH MAINLY OVERLAPPING BACKGROUND SOUTH SWELLS MOVING
THROUGH. A LARGER PULSE OF SOUTH-SOUTHWEST SWELL MAY ARRIVE
TUESDAY.
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...FOSTER
AVIATION...WALSH
MARINE...WROE
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