373
FXHW60 PHFO 021930
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
930 AM HST THU APR 2 2026
SYNOPSIS
TYPICAL MODERATE TO LOCALLY BREEZY TRADE WINDS WILL CONTINUE
THROUGH THIS WEEKEND AND BRING MAINLY NIGHT AND MORNING SCATTERED
SHOWERS TO WINDWARD AND MAUKA LOCATIONS. BY EARLY NEXT WEEK, A
DEEPENING TROUGH NORTHWEST OF THE STATE WILL PULL UP A MORE
MOISTURE RICH TROPICAL AIR MASS OVER THE STATE AND INCREASE
PRECIPITATION CHANCES. SOME OF THE RAIN COULD BE HEAVY, ESPECIALLY
MID- TO LATE NEXT WEEK.
SHORT TERM UPDATE
ISSUED AT 930 AM HST THU APR 2 2026
RADAR SHOWS ONLY ISOLATED LIGHT SHOWERS THIS MORNING. SATELLITE
SHOWS A LONG PLUME OF CIRRUS MOVING OVER THE STATE FROM THE WSW,
AND THIS SHOULD BE WITH US ALL DAY AND INTO TONIGHT. WE EXPECT A
SLIGHT INCREASE IN TRADE SHOWERS THIS AFTERNOON AND TONIGHT, AND
THIS IS ALREADY HANDLED BY THE CURRENT FORECAST. NO CHANGES ARE
NEEDED AT THIS TIME.
PLEASE NOTE: THE LATEST MODELS, INCLUDING ENSEMBLES, CONTINUE TO
SHOW THE POTENTIAL FOR A HEAVY RAIN EVENT BEGINNING IN THE MIDDLE
OF NEXT WEEK AND EXTENDING INTO THE WEEKEND. A NEW ROUND OF
FLOODING MAY OCCUR IF THESE MODELS ARE ACCURATE. DETAILS (WHICH
ISLAND(S) MAY BE HIT HARDEST, EXACT TIMING, ETC) ARE NOT AVAILABLE
THIS FAR OUT DUE TO THE REALITY OF MODEL ACCURACY IN THE TROPICS.
PLEASE STAY AWARE OF THE EVOLVING FORECAST BECAUSE THIS SYSTEM
MAY BECOME A SERIOUS PROBLEM.
PREV DISCUSSION
ISSUED AT 331 AM HST THU APR 2 2026
WATER VAPOR IMAGERY LOOP FROM THIS MORNING SHOWED VERY DRY AIR IN
THE MID AND UPPER LEVELS ENTRENCHED OVER AND EAST OF THE STATE,
ASIDE FROM A THIN LAYER OF HIGH CLOUDS PASSING OVER THE BIG
ISLAND. THIS CAN ALSO BE NOTED ON THE LATEST 12Z RAOB SOUNDINGS
FROM BOTH HILO AND LIHUE, WITH A RATHER DRAMATIC DRY LAYER
RESIDING ABOVE A 6000 FT DEEP BOUNDARY LAYER TEMPERATURE
INVERSION. AT THE SURFACE, AN AREA OF HIGH PRESSURE, ANCHORED
ROUGHLY 1000 MILES NORTH OF HAWAII CONTINUED TO DRIVE MODERATE TO
LOCALLY BREEZY EAST NORTHEASTERLY TRADES. SCATTERED LOW CLOUDS
CAUGHT UP IN THIS FLOW HAVE BEEN PUSHING TOWARDS WINDWARD PORTIONS
OF THE ISLANDS FOR THE LAST SEVERAL HOURS. SEVERAL WINDWARD
STATIONS ON EACH ISLAND PICKED OF A FEW HUNDREDTHS OF AN INCH OF
ACCUMULATION, BUT NOTHING OF SIGNIFICANCE.
TODAY THROUGH FRIDAY, THE PATTERN WILL CHANGE VERY LITTLE WITH
MODERATE TO LOCALLY BREEZY TRADES DRIVING LIGHT SCATTERED SHOWERS
ALONG MAINLY WINDWARD AND MAUKA LOCATIONS. THE GREATEST SHOWER
ACTIVITY CAN BE EXPECTED TO OCCUR DURING THE NIGHT AND EARLY
MORNING HOURS. BY THIS WEEKEND, THE AFOREMENTIONED HIGH WELL NORTH
OF THE AREA DRIFTS EAST AS A FRONTAL SYSTEM APPROACHES. THIS
SHOULD ALLOW THE LOCAL SURFACE PRESSURE GRADIENT AROUND THE REGION
TO EASE AND TRADES TO WEAKEN SLIGHTLY. LOW CLOUDS AND SHOWERS WILL
BE ISOLATED AT BEST WITH A SHALLOW BOUNDARY LAYER IN THE LOWER
LEVELS AND DRY AIR IN PLACE ALOFT.
BY MONDAY, BOTH THE GFS AND ECMWF BEGIN TO DIG A BROAD UPPER
TROUGH WELL NORTHWEST OF THE STATE. LIGHT BACKGROUND FLOW AROUND
THE ISLANDS WILL BECOME SOUTHEASTERLY, VEERING TO SOUTHERLY LATE
TUESDAY. WITH SUCH LIGHT FLOW AND SLIGHTLY DEEPER LOWER LEVEL
MOISTURE IN PLACE, AFTERNOON SEA BREEZES COULD HELP INITIATE A FEW
SHOWERS OVER INTERIOR PORTIONS OF THE ISLANDS.
MID TO LATE NEXT WEEK, MODELS CONTINUE TO DEEPEN THE UPPER LEVEL
TROUGH WEST OF THE ISLANDS AND INDUCE A LOW AND COLD FRONT AT THE
SURFACE. GUIDANCE HAS BEEN CONSISTENT WITH THIS SOLUTION FOR THE
LAST SEVERAL RUNS, SO CONFIDENCE IS INCREASING. THIS WOULD SET THE
STAGE FOR TROPICAL MOISTURE BEING DRAWN NORTHWARD ACROSS THE
HAWAIIAN ISLANDS BY DEEP LAYER SOUTHERLY OR SOUTH SOUTHWESTERLY
FLOW OUT AND A DESTABILIZING ATMOSPHERE ALOFT. AS IT STANDS, THE
ECMWF GENERATES A MORE COMPACT AND ROBUST PARENT SURFACE LOW
COMPARED TO THE GFS. NONETHELESS, BOTH MODELS INDICATE THE
POTENTIAL FOR GUSTY SOUTHERLY WINDS AND ROUNDS OF MODERATE TO
HEAVY RAIN. THUS, FLOODING MAY ONCE AGAIN BE A CONCERN. THE
DETAILS FOR TIMING, LOCATION, AND STRENGTH WILL NEED TO BE REFINED
IN THE COMING DAYS.
AVIATION
ISSUED AT 930 AM HST THU APR 2 2026
MODERATE TRADES WITH OCCASIONAL LIGHT SHOWERS PRIMARILY FOCUSING
ON WINDWARD AND UPSLOPE MAUKA AREAS. BETTER ORGANIZED SHOWERS WILL
BRIEFLY LOWER CEILINGS AND VISIBILITIES INTO MVFR CATEGORIES.
OTHERWISE, PREVAILING VFR CONDITIONS.
AN AIRMET IS IN EFFECT FOR THE ENTIRE AREA FOR MODERATE TURBULENCE
BETWEEN FL280 AND FL380. THE PASSAGE OF A JET STREAK WITHIN THE
SUBTROPICAL JET MOVING OVER THE ISLANDS MAY INITIATE SEVERE
TURBULENCE LATER THIS EVENING.
MARINE
ISSUED AT 930 AM HST THU APR 2 2026
WEAKENING HIGH PRESSURE NORTH OF THE ISLANDS WILL SHIFT EASTWARD
OVER THE NEXT FEW DAYS, LEADING TO A WEAKENING OF THE TRADE WINDS
INTO THE MODERATE TO FRESH RANGE. WINDS BEGIN TO VEER EAST TO
SOUTHEAST EARLY NEXT WEEK AHEAD OF A FRONT APPROACHING FROM THE
NORTHWEST. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE
TYPICALLY WINDIER WATERS AROUND MAUI COUNTY AND THE BIG ISLAND
THROUGH TONIGHT.
THE SHORT PERIOD NORTHEAST SWELL WILL CONTINUE A GRADUAL DECREASE
THROUGH THE WEEKEND AS THE NORTHEAST TRADE WINDS SLOWLY DIMINISH. AS
A RESULT, SURF ALONG NORTH- AND EAST-FACING SHORES SURF WILL
GRADUALLY DECLINE THROUGH THE REST OF THE WEEK, BUT WILL STILL RETAIN
A LITTLE SIZE AND CHOP DUE TO THE MODERATE TO LOCALLY BREEZY TRADES.
NORTH- AND WEST-FACING SHORE SURF WILL REMAIN SMALL TO TINY UNTIL THE
ARRIVAL OF A SMALL, MEDIUM-PERIOD WEST-NORTHWEST (310 DEGREE) SWELL
FRIDAY NIGHT AND A SECOND SMALL, MEDIUM-PERIOD NORTHWEST (340 DEGREE)
SWELL LATE SATURDAY. A SMALL TO MODERATE MEDIUM-PERIOD WEST-
NORTHWEST SWELL LOOKS TO ARRIVE EARLY NEXT WEEK AND FILLS IN BY MID-
WEEK. ALONG SOUTH FACING SHORES, EXPECT SMALL REINFORCEMENTS TO
PROVIDE PERIODS OF SMALL SURF THROUGH THE WEEKEND UNTIL A SLIGHTLY
LARGER LONG PERIOD SOUTH SWELL FILLS IN EARLY NEXT WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
MAALAEA BAY-PAILOLO CHANNEL.
SHORT TERM UPDATE...PARKER
DISCUSSION...THOMAS
AVIATION...BLOOD
MARINE...QUESADA
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