688
FXHW60 PHFO 040701
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
901 PM HST FRI APR 3 2026
SYNOPSIS
MOSTLY DRY AND PLEASANT TRADE WIND WEATHER WILL CONTINUE THROUGH
THE WEEKEND AND INTO MONDAY, WITH BRIEF PASSING SHOWERS FAVORING
WINDWARD AND MAUKA AREAS. A SIGNIFICANT PATTERN CHANGE IS THEN
EXPECTED BY LATE TUESDAY INTO MIDWEEK AS AN UPPER DISTURBANCE AND
SURFACE LOW PRESSURE EVOLVE NORTHWEST OF THE ISLANDS. THIS SETUP
IS EXPECTED TO DRAW DEEP TROPICAL MOISTURE NORTHWARD OVER THE
STATE, LEADING TO BREEZY SOUTHERLY WINDS, INCREASING CHANCES FOR
WIDESPREAD RAINFALL, AND RENEWED FLOODING CONCERNS FROM MIDWEEK
THROUGH NEXT WEEKEND. GIVEN RECENT HISTORIC FLOOD EVENTS AND SOILS
THAT REMAIN ONLY PARTIALLY RECOVERED, THE POTENTIAL FOR RUNOFF
AND FLASH FLOODING IMPACTS MAY INCREASE RAPIDLY.
DISCUSSION
A RELATIVELY BENIGN TRADE WIND PATTERN REMAINS IN PLACE ACROSS
THE HAWAIIAN ISLANDS THIS EVENING AND IS EXPECTED TO PERSIST
THROUGH THE WEEKEND INTO MONDAY. MODERATE EASTERLY TRADES WILL
CONTINUE TO FOCUS BRIEF SHOWERS ALONG WINDWARD AND MAUKA SLOPES,
WHILE LEEWARD AREAS REMAIN MOSTLY DRY. OVERALL, RAINFALL AMOUNTS
DURING THIS PERIOD SHOULD REMAIN LIGHT, WITH THE BEST COVERAGE
EXPECTED THROUGH THE OVERNIGHT AND EARLY MORNINGS.
GLOBAL GUIDANCE REMAINS IN DECENT AGREEMENT AND DEPICTS A NOTABLE
AMPLIFICATION OF THE LARGE-SCALE PATTERN ACROSS THE CENTRAL
PACIFIC EARLY NEXT WEEK. A SERIES OF SHORTWAVE TROUGHS DIGGING
SOUTHEASTWARD TOWARD THE STATE WILL TRANSLATE TO LARGE-SCALE
UPPER HEIGHT FALLS ACROSS THE REGION. THE SURFACE RIDGE TO THE
NORTH WILL GRADUALLY ERODE AS AN ATTENDANT SURFACE LOW EVOLVES TO
THE NORTHWEST. THIS WILL DISRUPT THE TYPICAL TRADE WIND FLOW BY
TUESDAY AND ALLOW LOW-LEVEL WINDS TO VEER OUT OF THE SOUTHEAST TO
SOUTH BY WEDNESDAY.
THIS TRANSITION TO SOUTHERLY FLOW WILL DRAW DEEP TROPICAL MOISTURE
NORTHWARD INTO THE ISLANDS BEGINNING TUESDAY NIGHT AND ESPECIALLY
WEDNESDAY INTO THURSDAY. PRECIPITABLE WATER VALUES ARE FORECAST
TO CLIMB TOWARD 2 INCHES OR HIGHER, SIGNALING A MARKED INCREASE IN
MOISTURE.
CONFIDENCE IS INCREASING THAT THE WEDNESDAY THROUGH THE SECOND
HALF OF THE WEEK PERIOD MAY PRESENT THE HIGHEST POTENTIAL FOR
WIDESPREAD RAINFALL AND FLOODING IMPACTS. DURING THIS TIME, UPPER-
LEVEL FORCING IS EXPECTED TO STRENGTHEN AS A STRONG SHORTWAVE
ROUNDS THE BASE OF THE TROUGH, POTENTIALLY ENHANCING LIFT OVER THE
REGION WHILE LOW PRESSURE ORGANIZES NORTHWEST OF THE ISLANDS. THE
COMBINATION OF DEEP MOISTURE, INCREASING LARGE-SCALE FORCING FOR
ASCENT, AND BREEZY SOUTHERLY WINDS FAVORS A TRANSITION TOWARD A
MORE WIDESPREAD AND ORGANIZED RAINFALL EVENT. IN ADDITION TO THE
RAINFALL CONCERNS DURING THIS PERIOD, A FEW THUNDERSTORMS ALONG
WITH GUSTY DOWNSLOPING WINDS FOR NORTH AND WINDWARD SIDES OF THE
ISLANDS CAN'T BE RULED OUT.
ALTHOUGH FORECAST CONFIDENCE BEGINS TO LOWER BY NEXT WEEKEND DUE
TO MODEL DIFFERENCES, THE GENERAL LARGE SCALE PATTERN COULD LINGER.
THIS SCENARIO SUGGESTS THE POTENTIAL FOR RAIN COULD PERSIST
THROUGH NEXT WEEKEND FOR AT LEAST PARTS OF THE STATE OR WHERE THE
DEEP MOISTURE AXIS ANCHORS.
REGARDLESS OF THE PRECISE EVOLUTION, ANTECEDENT CONDITIONS REMAIN
A SIGNIFICANT CONCERN. THE ISLANDS HAVE EXPERIENCED MULTIPLE
SIGNIFICANT FLASH FLOOD EVENTS IN RECENT WEEKS, AND DESPITE
SEVERAL DAYS OF DRIER TRADE WIND WEATHER, SOILS REMAIN VULNERABLE
IN MANY AREAS. AS A RESULT, ANY PERIOD OF MODERATE TO HEAVY
RAINFALL NEXT WEEK MAY QUICKLY LEAD TO ENHANCED RUNOFF, RENEWED
RISES ON STREAMS AND RESERVOIRS, AND LOCALIZED FLASH FLOODING
CONCERNS.
THIS SYSTEM WILL CONTINUE TO BE MONITORED CLOSELY OVER THE COMING
DAYS, AS ADDITIONAL ADJUSTMENTS TO TIMING, DURATION, AND IMPACT
MESSAGING ARE LIKELY AS THIS CHANGE IN THE PATTERN EVOLVES.
AVIATION
THE TRADE WIND PATTERN AND VFR CONDITIONS WILL CONTINUE INTO
SATURDAY. TEMPORARY MVFR CONDITIONS ARE POSSIBLE IN WINDWARD
LOCATIONS IN ANY SHOWER THAT DEVELOP, CREATING LOWERED VISIBILITIES
AND CEILINGS.
OVERALL, TURBULENCE HAS WEAKENED, SO AIRMET TANGO HAS BEEN
CANCELED.
MARINE
MODERATE TO LOCALLY FRESH EAST-NORTHEASTERLY TRADE WINDS WILL
REMAIN IN PLACE THROUGH THE WEEKEND. WINDS WILL THEN BEGIN TO VEER
EAST TO SOUTHEAST BY MONDAY, THEN BECOME MORE SOUTHERLY AHEAD OF
A FRONT APPROACHING FROM THE NORTHWEST AND A TROUGH MOVING UP
FROM THE SOUTHWEST. THIS SURFACE FRONT AND TROUGH WILL BE DRIVEN
BY AN UPPER LEVEL TROUGH, WHICH COULD ALLOW FOR ISOLATED
THUNDERSTORMS OVER THE OFFSHORE AND COASTAL WATERS THROUGH MUCH OF
NEXT WEEK. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE
TYPICALLY WINDIER WATERS AROUND MAUI COUNTY AND THE BIG ISLAND
THROUGH TONIGHT.
SURF ALONG NORTH-FACING SHORES WILL REMAIN TINY TO SMALL THROUGH
THE WEEKEND AS A SHORT-PERIOD NORTHEAST SWELL FADES AND SMALL
NORTHWEST PULSES FILL IN. TONIGHT INTO SATURDAY, SMALL, MEDIUM-
PERIOD WEST-NORTHWEST (310 DEGREE) ENERGY WILL FILL IN AND ON
SATURDAY NIGHT INTO SUNDAY, SMALL, MEDIUM-PERIOD NORTHWEST
(330-340 DEGREE) ENERGY WILL ALSO FILL IN. BOTH OF THESE SMALL
SWELLS WILL BUMP UP SURF SLIGHTLY FOR NORTH AND WEST FACING
SHORES. THEN BY MONDAY NIGHT THROUGH WEDNESDAY, A MODERATE MEDIUM-
PERIOD WEST-NORTHWEST (310 DEGREE) SWELL WILL FILL IN AND
INCREASE SURF TO JUST BELOW ADVISORY LEVELS.
ALONG SOUTH FACING SHORES, EXPECT MINOR PULSES FROM THE SOUTH
PACIFIC TO PROVIDE PERIODS OF SMALL SURF THROUGH THE WEEKEND
UNTIL A LARGER LONG-PERIOD SOUTH SWELL FILLS IN MONDAY AND LASTS
THROUGH AT LEAST MIDWEEK. IN ADDITION, STRENGTHENING SOUTHERLY
WINDS MAY LEAD TO INCREASINGLY CHOPPY CONDITIONS BY MIDWEEK.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST SATURDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
SYNOPSIS/DISCUSSION...GIBBS
AVIATION...PECHACEK
MARINE...FARRIS
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