215
FXHW60 PHFO 040103
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
303 PM HST FRI APR 3 2026
SYNOPSIS
MODERATE TRADES FOCUS SHOWERS WINDWARD AND MAUKA THROUGH THE
WEEKEND. A STRENGTHENING LOW THEN BRINGS POTENTIAL FOR HEAVY RAIN
TO THE ISLANDS FROM TUESDAY NIGHT ONWARD.
DISCUSSION
MODERATE TRADES FOCUS SHOWERS WINDWARD AND MAUKA, AND A ZONALLY
ORIENTED SUBTROPICAL JET FUNNELS ABUNDANT HIGH CLOUDS ACROSS AREA
SKIES. HIGH CLOUDS LIKELY CLEAR OUT DURING SATURDAY AS THE STJ
SAGS SOUTH THEN RETURN AGAIN SUNDAY AS SUBTLE RIDGING FORCES IT
NORTHWARD ONCE AGAIN. BENIGN STABLE TRADE WIND WEATHER THROUGH
MONDAY.
ATTENTION THEN TURNS TO FLOODING POTENTIAL BEGINNING LATE TUESDAY
OR WEDNESDAY AND PERSISTING FOR AN UNCERTAIN PERIOD OF TIME. THIS
EVENT WILL REPRESENT YET ANOTHER FLAVOR OF LOW PRESSURE EVOLUTION
DISTINCT FROM THE TWO RECENT EVENTS. OVERALL, CONFIDENCE IN
DETAILS (INCLUDING TIMING/DURATION/LOCATION) IS BELOW NORMAL
OWING TO THE DEPENDENCE OF THE UPPER AIR PATTERN ON THE
INTERACTION OF MULTIPLE RELATIVELY SMALL-SCALE SHORTWAVES WITH
THE LARGER SCALE FLOW.
LATE THIS WEEKEND, A MID-LATITUDE TROUGH WILL CROSS THE DATELINE
AND WILL SERVE AS THE WAVEGUIDE FOR A QUICK-MOVING SHORTWAVE THAT
WILL UNDERGO A DEEPENING SEQUENCE AS IT PASSES NORTH OF THE
ISLANDS EARLY TUESDAY. THIS WILL HELP ESTABLISH SURFACE PRESSURE
FALLS THAT WILL WEAKEN THE WIND FIELD WHILE ELICITING A SOUTHERLY
FLOW RESPONSE ALOFT THAT WILL DRAW ABUNDANT TROPICAL MOISTURE
NORTHWARD. SHORTWAVE RIDGING NATURALLY FOLLOWS ON TUESDAY NIGHT
SUGGESTING A MORE MUTED RESPONSE FOR ANY INITIAL WAVE OF RAIN
DURING THIS TIME. PWATS AROUND 2", AND STILL RISING, WILL LIKELY
BE ESTABLISHED BY WEDNESDAY MORNING. UPPER AIR EVOLUTION THEN
NEARLY REPEATS ITSELF ON WEDNESDAY AS ANOTHER QUICK-MOVING
SHORTWAVE DEEPENS AS IT APPROACHES THE BASE OF A TRAILING MID-
LATITUDE TROUGH. THERE IS STRONG CONSENSUS THAT PHASING ALOFT WILL
PRODUCE A MORE ROBUST SURFACE RESPONSE WEDNESDAY INTO THURSDAY.
AS SURFACE LOW PRESSURE DEVELOPS NW OF THE ISLANDS, THE AMBIENT
WIND FIELD RAMPS UP, AND WITH PLENTY OF MOISTURE ALREADY IN PLACE,
CONFIDENCE INCREASES IN THE WED-THURS TIME FRAME AS A TARGET FOR
FLOODING POTENTIAL.
MODEL CONSENSUS BREAKS DOWN THEREAFTER. THE GFS ALLOWS WEDNESDAY'S
DEEPENING TROUGH TO CUTOFF NW OF THE ISLANDS RESULTING IN MULTIPLE
PERIODS OF FORCING AS SHORTWAVES INTERACT WITH LINGERING MOISTURE
AND NUMEROUS WAVES OF RAIN EACH REPRESENTING A POTENTIAL FLOODING
THREAT. THE EC LIKEWISE ALLOWS MOISTURE TO REMAIN IN PLACE FOR A
PROLONGED PERIOD OF TIME, BUT IS CONSIDERABLY MORE PROGRESSIVE
WITH THE PARENT LOW AND SUGGESTS PERHAPS A WET PATTERN, BUT A LOW
MAGNITUDE ONE, AFTER THURSDAY. IT IS WORTH NOTING THAT WITH
MOISTURE REMAINING IN PLACE FOR THE FORESEEABLE FUTURE, FLASH
FLOOD POTENTIAL WILL LIKELY HAVE TO BE ASSESSED REGULARLY THROUGH
MID-APRIL AS ANY TROUGH INTRUDING FROM THE MID-LATITUDES WILL
HAVE POTENTIAL TO CAUSE TROUBLE.
AVIATION
THE TRADE WIND PATTERN AND VFR CONDITIONS WILL CONTINUE INTO
SATURDAY. TEMPORARY MVFR CONDITIONS ARE POSSIBLE IN WINDWARD
LOCATIONS IN ANY SHOWERS 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.
DISCUSSION...JVC
AVIATION...M BALLARD/PECHACEK
MARINE...FARRIS
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