769
FXHW60 PHFO 211317
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
317 AM HST THU AUG 21 2025
SYNOPSIS
HIGH PRESSURE NORTH OF THE ISLANDS WILL MAINTAIN MODERATE TO
LOCALLY BREEZY TRADE WINDS THROUGH AT LEAST THE WEEKEND. TYPICAL
STABLE SUMMERTIME CONDITIONS WILL BRING PERIODS OF MAINLY WINDWARD
AND MAUKA SHOWERS, WHILE MOST LEEWARD AREAS REMAIN RATHER DRY.
DISCUSSION
NO SIGNIFICANT CHANGES TO THE FORECAST THIS MORNING. MOST OF THE
GRIDS WERE UPDATED TO REFLECT THE LATEST RUN OF THE NATIONAL BLEND
OF MODELS, WITH LITTLE CHANGE TO THE OVERALL FORECAST. THE MAIN
CHANGE WAS A LOWERING OF THE POPS OVER WINDWARD BIG ISLAND OVER
THE NEXT COUPLE OF DAYS.
HIGH PRESSURE REMAINS FAR NORTH AND NORTHEAST OF THE ISLANDS,
DRIVING MODERATE TO LOCALLY BREEZY TRADES TO THE REGION. A MID-
LEVEL RIDGE OVER THE ISLANDS IS MAINTAINING STABLE CONDITIONS,
LIMITING RAINFALL TOTALS OVER MOST AREAS. A SHALLOW POOL OF
SHOWERS AND LOW CLOUDS CARRIED IN ON THE TRADES BROUGHT SOME
SHOWERS TO WINDWARD PORTIONS OF MAUI COUNTY AND THE BIG ISLAND
OVERNIGHT. SOME OF THAT MOISTURE IS EXPECTED TO REACH OAHU LATER
THIS MORNING. SATELLITE SHOWS LIMITED MOISTURE MOVING IN BEHIND
THIS POOL OF MOISTURE
LITTLE CHANGE TO THE TYPICAL MID AUGUST WEATHER PATTERN IS
EXPECTED THROUGH THE WEEKEND, FOLLOWED BY A POSSIBLE SLIGHT
DECLINE IN WINDS LATE SUNDAY INTO TUESDAY. A PERSISTENT MID-LEVEL
RIDGE WILL MAINTAIN STABILITY, AND LITTLE ORGANIZED MOISTURE IS
SEEN IN THE GUIDANCE UNTIL TUESDAY. AS A RESULT, EXPECT LIMITED
WINDWARD RAINFALL, AND WITH THE EXCEPTION OF THE KONA SLOPES OF
THE BIG ISLAND, MOST LEEWARD AREAS WILL REMAIN RATHER DRY.
AVIATION
HIGH PRESSURE TO THE NORTHEAST OF THE ISLANDS WILL MAINTAIN
MODERATE TO LOCALLY BREEZY TRADE WINDS OVER THE NEXT COUPLE OF
DAYS. CLOUDS AND SHOWERS WILL REMAIN FOCUSED OVER THE WINDWARD
AND MOUNTAIN AREAS, PARTICULARLY OVERNIGHT AND INTO THE MORNING
HOURS. MVFR CONDITIONS WILL BE POSSIBLE IN SHOWERS, OTHERWISE VFR
WILL LIKELY PREVAIL.
NO AIRMETS ARE CURRENTLY IN EFFECT.
MARINE
A HIGH PRESSURE RIDGE NORTH OF THE HAWAIIAN ISLANDS WILL MAINTAIN
FRESH TO LOCALLY STRONG TRADE WINDS LASTING INTO EARLY NEXT WEEK.
THE SMALL CRAFT ADVISORY (SCA) REMAINS IN EFFECT FOR THE WINDIER
WATERS AND CHANNELS NEAR MAUI COUNTY AND THE BIG ISLAND THROUGH
SATURDAY. THIS SCA WILL LIKELY CONTINUE FOR THESE WINDIER WATERS
INTO EARLY NEXT WEEK.
A SERIES OF SMALL OVERLAPPING MEDIUM AND LONG PERIOD SOUTH
(170-190 DEGREE) SWELLS WILL CONTINUE FOR THE REST OF THIS WEEK,
WITH SURF HEIGHTS NEAR THE SUMMERTIME AVERAGE THROUGH SATURDAY
ALONG SOUTH FACING SHORES. THE LARGEST OF THESE SOUTH SWELLS WILL
ARRIVE IN THE ISLANDS LATER TODAY AND HOLD THROUGH FRIDAY. SURF
HEIGHTS SHOULD DECREASE TO BACKGROUND LEVELS EARLY NEXT WEEK AS
THE SWELL ENERGY FADES. ANOTHER SMALL, LONG PERIOD SOUTH SWELL
WILL ARRIVE BY NEXT WEEK TUESDAY.
CHOPPY CONDITIONS WILL CONTINUE FOR EAST FACING SHORES THROUGH
THE FORECAST PERIOD DUE TO THE PERSISTENT FRESH TRADES. SURF ALONG
NORTH FACING SHORES WILL REMAIN NEARLY FLAT THROUGH NEXT WEEK.
PEAK HIGH TIDES ASSOCIATED WITH THE LUNAR CYCLE WILL LEAD TO MINOR
COASTAL FLOODING ALONG SHORELINES AND LOW LYING COASTAL AREAS
DURING THE HIGH TIDE LATER THIS AFTERNOON. A COASTAL FLOOD
STATEMENT REMAINS IN EFFECT FOR MINOR COASTAL FLOODING IN LOW
LYING AREAS.
FIRE WEATHER
TRADE WINDS WILL REMAIN IN THE MODERATE TO LOCALLY BREEZY RANGE
INTO SUNDAY WHILE A RIDGE ALOFT MAINTAINS AN INVERSION BETWEEN
5,500 TO 7,000 FT. UNDER THIS RATHER TYPICAL AUGUST WEATHER
PATTERN, AFTERNOON RELATIVE HUMIDITY SHOULD REMAIN NEAR SUMMERTIME
AVERAGE ON THURSDAY. SLIGHTLY DRIER CONDITIONS ARE POSSIBLE
FRIDAY INTO THE WEEKEND. AS A RESULT, NEAR CRITICAL FIRE WEATHER
CONDITIONS ARE EXPECTED, THOUGH WE DO NOT ANTICIPATE FIRE WEATHER
HEADLINES AT THIS TIME.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST SATURDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...M BALLARD
AVIATION...M BALLARD
MARINE...BOHLIN
FIRE WEATHER...M BALLARD
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