401
FXHW60 PHFO 170642
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
842 PM HST MON MAR 16 2026
SYNOPSIS
UNSETTLED WEATHER WILL PERSIST ACROSS THE HAWAIIAN ISLANDS
THROUGH THE WEEK IN THE WAKE OF THE RECENT KONA STORM. ALTHOUGH A
BRIEF LULL IN WIDESPREAD HEAVY RAINFALL IS EXPECTED THROUGH
MIDWEEK, DEEP TROPICAL MOISTURE WILL REMAIN IN PLACE AND SUPPORT
PERIODS OF SHOWERS, PARTICULARLY OVER THE EASTERN END OF THE
STATE. CONDITIONS ARE EXPECTED TO DETERIORATE AGAIN DURING THE
SECOND HALF OF THE WEEK AS ANOTHER UPPER-LEVEL DISTURBANCE AND
SURFACE LOW APPROACH FROM THE WEST, BRINGING INCREASING CHANCES
FOR WIDESPREAD RAINFALL AND RENEWED KONA WINDS. WITH SOILS ALREADY
SATURATED, ADDITIONAL RAINFALL COULD QUICKLY LEAD TO RUNOFF AND
FLOODING IMPACTS.
DISCUSSION
IN THE WAKE OF THE SIGNIFICANT KONA LOW THAT IMPACTED THE STATE
OVER THE PAST SEVERAL DAYS, A BROAD AND PERSISTENT UPPER-LEVEL
TROUGH REMAINS ANCHORED OVER THE REGION. WHILE THE KONA LOW HAS
WEAKENED AND LIFTED AWAY, THE LARGER-SCALE PATTERN REMAINS LARGELY
UNCHANGED, WITH DEEP TROPICAL MOISTURE CONTINUING TO STREAM
NORTHWARD OVER THE STATE. PRECIPITABLE WATER VALUES REMAIN
ANOMALOUSLY HIGH, MAINTAINING A MOIST AIR MASS ACROSS THE REGION.
MODEL GUIDANCE CONTINUES TO INDICATE A RELATIVE DECREASE IN
WIDESPREAD HEAVY RAINFALL THROUGH THE NEXT COUPLE OF DAYS,
PARTICULARLY OVER THE WESTERN END OF THE STATE. HOWEVER, THIS
SHOULD NOT BE INTERPRETED AS A RETURN TO BENIGN CONDITIONS.
PERIODS OF SHOWERS WILL PERSIST WITHIN THE MOIST/DEEP
SOUTHWESTERLY FLOW, WITH LOCALLY HEAVY RAINFALL STILL POSSIBLE,
ESPECIALLY ACROSS MAUI COUNTY AND THE BIG ISLAND WHERE THE AXIS OF
DEEPEST MOISTURE IS EXPECTED TO REMAIN FOCUSED THROUGH MIDWEEK.
BY THE LATTER HALF OF THE WEEK, THE UPPER-LEVEL TROUGH IS
FORECAST TO DEEPEN WEST OF THE STATE. THIS FEATURE IS EXPECTED TO
RE-EXPAND THE AXIS OF ANOMALOUS MOISTURE BACK ACROSS THE ENTIRE
ISLAND CHAIN WHILE INCREASING LARGE-SCALE ASCENT. AT THE SURFACE,
LOW PRESSURE IS FORECAST TO DEVELOP AND APPROACH THE ISLANDS, WITH
POTENTIALLY BREEZY KONA WINDS AND DEWPOINTS CLIMBING BACK TOWARD
70 DEGREES.
THIS EVOLVING PATTERN WILL SUPPORT A RENEWED INCREASE IN SHOWER
COVERAGE AND INTENSITY FROM LATE WEEK INTO THE WEEKEND, WITH MODEL
CONSENSUS SUGGESTING AN ADDITIONAL SEVERAL INCHES OF RAINFALL
POSSIBLE OVER PORTIONS OF THE STATE DURING THIS PERIOD. WHILE
THIS NEXT SYSTEM DOES NOT CURRENTLY APPEAR TO BE AS INTENSE AS
THE RECENT EVENT, IT WILL IMPACT AN ALREADY HIGHLY SATURATED
ENVIRONMENT.
GIVEN THE ANTECEDENT CONDITIONS, INCLUDING ELEVATED STREAMS AND
SATURATED SOILS, EVEN MODERATE RAINFALL RATES MAY QUICKLY LEAD TO
RUNOFF ISSUES. THE THREAT FOR FLASH FLOODING WILL REMAIN ELEVATED
STATEWIDE THROUGH THE WEEK, WITH THE POTENTIAL FOR MORE SIGNIFICANT
IMPACTS RETURNING LATE IN THE WEEK INTO NEXT WEEKEND.
AVIATION
SHOWERS CONTINUE TO BRING INTERMITTENT MVFR AND IFR CONDITIONS TO
PHKO ON THE BIG ISLAND THIS EVENING. BANDS OF SHOWERS CONTINUE TO
MOVE IN FROM THE WEST THIS EVENING AS A SURFACE TROUGH MOVES INTO
THE STATE. THIS BAND OF SHOWERS WILL MOVE THROUGH KAUAI, OAHU,
AND MAUI BEFORE REINFORCING THE SHOWERS ON THE BIG ISLAND TUESDAY.
OCCASIONAL MVFR IS LIKELY WITH ISOLATED PERIODS OF IFR THROUGH
THE FORECAST PERIOD.
AIRMET SIERRA HAS BEEN EXPANDED FOR MOUNTAIN OBSCURATION FOR KAUAI
AND MAINTAINING IT FOR MAUI, LANAI, AND THE BIG ISLAND AND WILL
LIKELY BE EXTENDED THROUGH TUESDAY MORNING.
MARINE
THE GRADIENT WILL REMAIN RATHER WEAK THROUGH WEDNESDAY, WITH
LIGHT AND VARIABLE WINDS PREVAILING OVER THE WATERS. A BRIEF
PERIOD OF LIGHT TO MODERATE TRADES WILL BE POSSIBLE THURSDAY AS A
WEAK RIDGE BUILDS NORTH OF THE STATE, FOLLOWED BY LIGHT TO
MODERATE S WINDS ON FRIDAY AS A NEW SYSTEM APPROACHES FROM THE
WEST.
SURF ALONG S SHORES IS TRENDING DOWN AS S TO SW WINDS EASE. A NEW
LONG PERIOD SOUTH SWELL WILL THEN ARRIVE LATE TONIGHT AND TUESDAY
GIVING AN EXTENDED BOOST TO S SHORE SURF THROUGH LATE THIS WEEK.
A MODERATE SHORT-PERIOD W SWELL ASSOCIATED WITH THE RECENT KONA
STORM IS AFFECTING N AND W FACING SHORES TODAY, BUT SURF REMAINS
BELOW THE ADVISORY THRESHOLD. THE SHORT-PERIOD W SWELL WILL LOWER
TONIGHT AND TUESDAY WHILE A NEW MEDIUM-PERIOD NNW SWELL FILLS IN.
THIS NNW SWELL COULD ELEVATE SURF TO NEAR THE ADVISORY THRESHOLD
TUESDAY NIGHT AND WEDNESDAY. THE SWELL THEN SHIFTS MORE N AND
LOWERS THURSDAY INTO THE WEEKEND.
SURF ALONG E FACING SHORES WILL REMAIN WELL BELOW NORMAL THROUGH
LATE WEEK AS TRADES OVER AND UPSTREAM OF THE ISLANDS REMAIN
DISRUPTED.
HFO WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY UNTIL 6 PM HST WEDNESDAY FOR HALEAKALA SUMMIT-BIG
ISLAND SUMMITS.
DISCUSSION...GIBBS
AVIATION...SHIGESATO
MARINE...JVC
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