287
FXHW60 PHFO 271956
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
956 AM HST MON APR 27 2026
SYNOPSIS
A HIGH PRESSURE SYSTEM FAR NORTH OF THE HAWAIIAN ISLANDS WILL
SLOWLY DRIFT EAST, HOWEVER A BROAD RIDGE NORTH OF THE REGION WILL
REMAIN IN PLACE KEEPING EASTERLY TRADE WINDS IN THE FORECAST
INTO THE WEEKEND. AN UPPER LEVEL TROUGH APPROACHING THE ISLANDS
TODAY WILL DEEPEN INTO AN UPPER LOW NEAR KAUAI BY TUESDAY, LEADING
TO INCREASING CLOUD AND SHOWER TRENDS ACROSS THE REGION THROUGH
THE WEEK. SHOWER ACTIVITY WILL FAVOR WINDWARD MOUNTAIN AREAS IN
THE OVERNIGHT TO EARLY MORNING HOURS WITH BRIEF PERIODS OF SHOWERS
DRIFTING INTO LEEWARD AREAS.
SHORT TERM UPDATE
ISSUED AT 953 AM HST MON APR 27 2026
MODERATE TRADE WINDS ARE PREVAILING ACROSS THE REGION TODAY.
LATEST SATELLITE AND RADAR IMAGERY SHOWS A FEW SHOWERS EMBEDDED
WITHIN THE TRADE WIND FLOW. SHOWER ACTIVITY WILL BE PRIMARILY
FOCUSED ALONG WINDWARD AND MAUKA AREAS. THE FORECAST GENERALLY
REMAINS ON TRACK, THOUGH A FEW MINOR TWEAKS HAVE BEEN MADE TO THE
FORECAST THIS AFTERNOON AND TOMORROW AFTERNOON.
PREV DISCUSSION
ISSUED AT 335 AM HST MON APR 27 2026
THE SATELLITE PICTURE THIS MORNING SHOWS CLOUDS SURROUNDING A LOW
LEVEL TROUGH THAT CONTINUES TO DRIFT WESTWARD WITH THE TROUGH
AXIS CURRENTLY JUST WEST OF KAUAI. HIGH LEVEL CIRRUS CLOUDS,
ASSOCIATED WITH A SUB TROPICAL JET STREAM SOUTH OF THE ISLANDS,
WILL CONTINUE TO STREAM OVER THE BIG ISLAND TODAY. AN UPPER LEVEL
TROUGH APPEARS ON WATER VAPOR IMAGERY APPROACHING THE ISLAND CHAIN
FROM THE NORTHWEST DIRECTION
AN UPPER LEVEL TROUGH APPROACHING THE HAWAIIAN ISLANDS FROM THE
NORTHWEST DIRECTION WILL ENHANCE SHOWER ACTIVITY ACROSS THE REGION
THROUGH TUESDAY. MODELS ARE IN GOOD AGREEMENT THAT THIS UPPER
TROUGH WILL DEEPEN INTO A WEAK CLOSED LOW NEAR KAUAI BY TUESDAY. A
WEAKNESS IN THE 500 MB HEIGHT FIELDS ARE A GOOD INDICATOR OF A
WEAK UPPER LOW THAT THE GLOBAL MODELS ARE UNABLE TO RESOLVE DUE TO
RESOLUTION ISSUES. EXPECT TEMPERATURE INVERSION HEIGHTS TO RISE
FROM 6,000 TO 8,000 FEET ELEVATION DURING THIS TIME PERIOD,
DEEPENING CLOUD HEIGHTS, PRODUCING A WET TRADE WIND WEATHER
PATTERN ACROSS THE STATE.
THIS DEVELOPING UPPER LOW WILL SLOWLY DRIFT EASTWARD ACROSS THE
REGION ON TUESDAY WITH A TROUGHING PATTERN LINGERING JUST
NORTHEAST OF THE STATE INTO FRIDAY. THE UPPER LOW'S UPSTREAM
POSITION, JUST NORTHEAST OF THE ISLANDS, WILL LIFT THE CLOUDS TO
HIGHER HEIGHTS, PRODUCING CONTINUED WET TRADE WIND WEATHER
CONDITIONS. THESE SHOWERS WILL FAVOR WINDWARD ISLAND MOUNTAIN
SLOPES, ESPECIALLY DURING THE DIURNAL RAINFALL MAXIMUM OVERNIGHT
TO EARLY MORNING HOURS. PERIODS OF PASSING SHOWERS WILL CONTINUE
THROUGHOUT THE WEEK AND INTO THE WEEKEND DUE TO THE PERSISTENT
UNSTABLE TROUGH SETTING UP JUST NORTHEAST OF THE ISLANDS.
AVIATION
ISSUED AT 335 AM HST MON APR 27 2026
MODERATE TRADES WILL CONTINUE THROUGH THE PERIOD. INTERMITTENT
MVFR IS POSSIBLE ACROSS WINDWARD SITES DUE TO LOW CIGS AND
SHOWERS, BUT VFR CONDITIONS ARE BROADLY ANTICIPATED. SHOWER
ACTIVITY MAY RAMP UP STARTING AROUND SUNSET AS AN UPPER LEVEL
SYSTEM MOVES TOWARD THE ISLANDS.
NO AIRMETS ARE IN EFFECT, HOWEVER A MOUNTAIN OBSCURATION AIRMET
MAY BE NEEDED IF LOW CLOUDS BECOME MORE WIDESPREAD DUE TO ONCOMING
SHOWER ACTIVITY.
MARINE
ISSUED AT 335 AM HST MON APR 27 2026
MODERATE TO FRESH EASTERLY TRADES WILL CONTINUE THROUGH TUESDAY,
THEN STRENGTHEN BY MIDWEEK AS A WEAK TROUGH SHIFTS TO THE WEST
AND THE RIDGE BUILDS NORTH OF THE STATE. THIS WILL LIKELY
CORRESPOND TO SMALL CRAFT ADVISORY WINDS ACROSS THE TYPICALLY
WINDIER WATERS SURROUNDING MAUI COUNTY AND THE BIG ISLAND
BEGINNING BY WEDNESDAY.
SURF ALONG EXPOSED NORTH- AND WEST-FACING SHORES WILL GRADUALLY
EASE INTO TUESDAY AS A NORTHWEST SWELL LOWERS. AN UPWARD TREND IS
EXPECTED DURING THE SECOND HALF OF THE WEEK AS SWELL GENERATED BY
A BROAD LOW THAT HAS LIFTED NORTH INTO THE BERING SEA NEAR THE
DATE LINE REACHES THE ISLANDS. LOOKING FURTHER AHEAD, CONFIDENCE
REMAINS LOWER DUE TO MODEL DIFFERENCES, BUT SOME GUIDANCE
CONTINUES TO SUGGEST A MORE POTENT STORM EVOLVING OVER THE FAR
NORTHWEST PACIFIC OVER THE NEXT COUPLE OF DAYS. IF THIS SCENARIO
MATERIALIZES, A LONGER-PERIOD NORTHWEST SWELL COULD ARRIVE BY THE
WEEKEND, WITH SURF HEIGHTS POTENTIALLY APPROACHING ADVISORY-LEVELS
ALONG EXPOSED NORTH AND WEST FACING SHORES.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN SMALL THROUGH MUCH OF
THE WEEK, WITH MAINLY BACKGROUND SOUTH TO SOUTHWEST SWELL EXPECTED.
ANOTHER SOUTH-SOUTHWEST PULSE MAY ARRIVE BY THIS WEEKEND FROM
RECENT ACTIVITY WITHIN OUR SWELL WINDOW EAST OF NEW ZEALAND.
SURF ALONG EAST-FACING SHORES WILL REMAIN RELATIVELY SMALL AND
CHOPPY DUE THROUGH MIDWEEK, WITH A SLIGHT RISE POSSIBLE LATER IN
THE WEEK AS TRADES STRENGTHEN.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM UPDATE...VAUGHAN
DISCUSSION...BOHLIN
AVIATION...EVANS
MARINE...GIBBS
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