537
FXHW60 PHFO 080225
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
425 PM HST MON SEP 7 2026
SYNOPSIS
SOUTHEAST TO SOUTH WINDS WILL STRENGTHEN TONIGHT AS HURRICANE
LOWELL APPROACHES. THE CORE OF LOWELL IS FORECAST TO PASS NEAR
NIIHAU TONIGHT INTO EARLY TUESDAY. DAMAGING HURRICANE CONDITIONS
ARE EXPECTED WITH NUMEROUS THREATS IN PLACE THROUGHOUT THE STATE.
A HURRICANE WARNING IS IN EFFECT FOR KAUAI AND NIIHAU AND A
TROPICAL STORM WARNING IS IN EFFECT FOR OAHU. HIGH SURF AND HEAVY
RAIN WILL IMPACT ALL ISLANDS WITH STRONG WINDS MAINLY IMPACTING
THE WESTERN END OF THE STATE.
DISCUSSION
HURRICANE LOWELL IS ABOUT 160 STATUTE MILES SOUTHWEST OF KAUAI
THIS AFTERNOON MOVING NORTH NORTHEASTWARD AT 18 MPH AS A HIGH END
CATEGORY 2 (MAXIMUM SUSTAINED WINDS OF 110 MPH). THE CORE OF
LOWELL IS EXPECTED TO PASS WEST OF NIIHAU, RAISING THE POSSIBILITY
OF HURRICANE FORCE WINDS REACHING KAUAI AND NIIHAU AND TROPICAL
STORM FORCE WINDS REACHING OAHU. AS A RESULT, A HURRICANE WARNING
IS IN PLACE FOR NIIHAU AND KAUAI AND A TROPICAL STORM WARNING IS
IN PLACE FOR OAHU. ON SATELLITE IMAGERY THIS AFTERNOON, BANDS OF
MODERATE RAIN WITH EMBEDDED HEAVY RAIN AND HAVE BEEN MOVING OVER
KAUAI, AND TO A LESSER EXTENT THE OTHER ISLANDS. THE SHOWER
FREQUENCY AND INTENSITY IS EXPECTED TO INCREASE TONIGHT AS LOWELL
MAKES ITS CLOSEST APPROACH. WINDS WILL ALSO TEND TO BE STRONGEST
WITHIN THE HEAVIER RAIN BANDS.
ADDITIONAL IMPACTS FROM LOWELL ARE EXPECTED STATEWIDE, AND A FEW
HEADLINES ARE IN EFFECT AS A RESULT. A HIGH SURF WARNING FOR SOUTH
FACING SHORES FOR THE SOUTH SWELL GENERATED BY LOWELL FOR ALL
ISLANDS, ALONG WITH THE WEST FACING SHORES OF THE BIG ISLAND. A
HIGH SURF ADVISORY REMAINS IN EFFECT FOR THE EAST SWELL GENERATED
BY FORMER TROPICAL STORM KARINA, WHICH HAS WEAKENED TO A POST
TROPICAL LOW. FOR SURF AND OTHER MARINE IMPACTS, PLEASE SEE THE
MARINE SECTION OF THE DISCUSSION BELOW.
THE FLOOD WATCH FOR THE STATE CONTINUES THROUGH TUESDAY DUE TO
HEAVY RAIN BROUGHT IN BY LOWELL AND ASSOCIATED RAIN AND
THUNDERSTORM BANDS. TERRAIN INFLUENCE WILL PLAY A BIG FACTOR WITH
ISOLATED AREAS RECEIVING SIGNIFICANT AMOUNTS THROUGH THE EVENT.
STAY ALERT FOR THE ISSUANCE OF ANY FUTURE FLOOD ADVISORIES OR
WARNINGS ACROSS THE STATE. SEE HYDROLOGY SECTION FOR ADDITIONAL
INFORMATION.
THE THREAT OF SHORT-LIVED, FAST-MOVING TORNADOS/WATERSPOUTS WILL
BE PRESENT MAINLY NEAR KAUAI AND NIIHAU AS LOWELL MAKES ITS
CLOSEST APPROACH TO THE ISLANDS. A TORNADO WATCH IS IN EFFECT FOR
KAUAI AND NIIHAU. ANY TORNADOES WOULD LIKELY BE EMBEDDED IN
RAINBANDS. THE THREAT FOR TORNADOES IS LOWER NEAR THE REMAINING
ISLANDS, BUT NOT ZERO. THE THREAT FOR TORNADOES SHOULD DECREASE
QUICKLY EARLY TUESDAY MORNING.
ANY DEVIATION IN TRACK OR INTENSITY COULD ALSO CHANGE HOW THESE
HAZARDS EFFECT THE ISLANDS.
HIGH PRESSURE IS FORECAST TO BUILD BACK IN THURSDAY THROUGH
SATURDAY, BRINGING IN A MORE TYPICAL TRADE WIND PATTERN. MOISTURE
MAY TAKE A BIT LONGER TO EXIT THE AREA AS WELL, SO CONDITIONS ARE
EXPECTED TO DRY OUT MORE GRADUALLY INTO THE WEEKEND.
AVIATION
HURRICANE LOWELL CONTINUES ITS TRACK NORTHWARD, ADVECTING UNSTABLE
DEEP TROPICAL MOISTURE NORTHWARD INTO THE ISLANDS. SHOWER
ACTIVITY WILL CONTINUE TO TREND HIGHER INTO TUESDAY. MVFR
CONDITIONS WITH LOW CLOUD CEILINGS AND SHOWERS ARE EXPECTED
STATEWIDE. HEAVIER SHOWERS WILL PRODUCE PERIODS OF IFR
CONDITIONS. SURFACE WINDS WILL CONTINUE TO STRENGTHEN TODAY OVER
THE WESTERN HALF OF THE STATE, AS HURRICANE LOWELL CONTINUES TO
MOVE NORTH.
AIRMET SIERRA FOR MOUNTAIN OBSCURATION CONTINUES FOR KAUAI OAHU
MOLOKAI MAUI AND THE BIG ISLAND. THIS AIRMET WILL LIKELY CONTINUE
INTO TUESDAY.
AIRMET TANGO WAS ISSUED FOR MODERATE LOW LEVEL TURBULENCE
AFFECTING THE ISLAND OF KAUAI OVER AND SW THRU NW OF ISLAND
MOUNTAINS. A STRONG SURFACE WIND AIRMET WAS ISSUED FOR KAUAI AND
NIIHAU FOR WIND SPEEDS GREATER THAN 30 KNOTS DUE TO HURRICANE
LOWELL APPROACHING THE ISLANDS.
LIGHT ICING CONTINUES IN A LAYER BETWEEN 160 AND FL220 DUE TO
STRENGTHENING LOW LEVEL WIND SPEEDS AS LOWELL APPROACHES THE
ISLAND.
MARINE
HURRICANE LOWELL CONTINUES TO MOVE NORTHWARD TOWARDS THE ISLANDS
THIS AFTERNOON. WINDS AND SEAS ARE ON THE INCREASE AS THE SYSTEM
APPROACHES, AND BOTH ARE EXPECTED TO PEAK OVERNIGHT AS LOWELL
MAKES IT CLOSEST APPROACH TO KAUAI COUNTY. A HURRICANE WARNING
REMAINS IN EFFECT FOR WATERS WEST OF KAUAI COUNTY, WHILE A
TROPICAL STORM WARNING REMAINS IN EFFECT FOR KAUAI CHANNEL, KAUAI
WINDWARD WATERS, OAHU WINDWARD WATERS AND OAHU LEEWARD WATERS.
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL REMAINING
COASTAL WATERS FOR A COMBINATION OF WINDS AND SEAS THROUGH
TUESDAY. WINDS ARE EXPECTED TO INCREASINGLY VEER TO THE SOUTHEAST
TO SOUTH AS LOWELL APPROACHES AND THE STRONGEST WINDS AND HIGHEST
SEAS ARE EXPECTED FOR THE WESTERN END OF THE STATE.
HURRICANE CONDITIONS ARE EXPECTED IN THE WESTERN OFFSHORE WATERS
THROUGH TUESDAY AS THE CENTER OF LOWELL TRACKS JUST WEST OF
NIIHAU. ANY SLIGHT DEVIATION IN THE TRACK TO THE WEST OR EAST IN
THE NEXT 12 TO 24 HOURS WILL HAVE SIGNIFICANT DIFFERENCES IN
IMPACT FOR THE COASTAL WATERS AROUND KAUAI COUNTY. WHAT REMAINS OF
FORMER TROPICAL CYCLONE KARINA REMAINS TO THE NORTHEAST OF THE
ISLANDS AND IS EXPECTED TO DISSIPATE SOON.
SOUTH-SOUTHWEST SWELL FROM HURRICANE LOWELL WILL CONTINUE TO BUILD
RAPIDLY, AND PEAK TONIGHT AS IT SHIFTS OUT OF THE SOUTHWEST. AS A
RESULT, WARNING LEVEL SURF ALONG SOUTH FACING SHORES WILL CONTINUE
TO RISE, PEAKING OVERNIGHT. DUE TO THE TRACK OF LOWELL WEST OF
THE MAIN ISLANDS, A SHARP GRADIENT IN SWELL IS EXPECTED FROM WEST
TO EAST. THIS WILL BRING DAMAGING SURF TO PORTIONS OF KAUAI COUNTY
AND LIKELY OAHU, WITH THE POTENTIAL FOR SIGNIFICANT DAMAGE TO
COASTAL PROPERTIES AND INFRASTRUCTURE, PARTICULARLY TO THOSE AREAS
ALONG THE COASTS OF KAUAI AND OAHU EXPOSED TO THE SOUTHERLY SWELL.
THE HURRICANE SWELL ENERGY IS EXPECTED TO RAPIDLY DECLINE ON
TUESDAY AS LOWELL MOVES AWAY FROM THE ISLANDS.
A MODERATE, LONG-PERIOD SOUTH SWELL WILL PEAK OVERNIGHT AND INTO
TUESDAY, BUT WILL BE OVERWHELMED BY THE LARGER SWELL MENTIONED
ABOVE FROM HURRICANE LOWELL. THIS SWELL WILL ALSO FADE SOME ON
TUESDAY BUT WILL KEEP SOUTH SHORE SURF SOMEWHAT ELEVATED THROUGH
THURSDAY. A LARGE, MEDIUM-PERIOD EAST SWELL FROM FORMER TROPICAL
STORM KARINA WILL COMBINE WITH INCREASING EAST TO SOUTHEAST WIND
WAVE GENERATED BY HURRICANE LOWELL TO KEEP ADVISORY LEVEL SURF
ALONG EAST FACING SHORES THROUGH TUESDAY. SURF ALONG NORTH FACING
SHORES WILL ALSO EXPERIENCE A SMALL INCREASE ON TUESDAY AS LOWELL
LIFTS NORTH OF THE ISLAND CHAIN AND THEN FADE THROUGH THE WEEK.
FIRE WEATHER
FIRE WEATHER RISK WILL REMAIN LOW THROUGH THE FORECAST PERIOD DUE
TO INCREASING MOISTURE MOVING OVER THE ISLANDS IN ASSOCIATION
WITH HURRICANE LOWELL. THUNDERSTORMS WILL BE POSSIBLE THROUGH
THROUGH TONIGHT TO THE UNSTABLE AIRMASS MOVING OVERHEAD.
TEMPERATURE INVERSION HEIGHTS ARE EXPECTED TO REMAIN ELEVATED OR
NON-EXISTENT DURING THE NEXT FEW DAYS.
HYDROLOGY
THUS FAR, AROUND 6 TO 10 INCHES OF RAIN HAVE FALLEN ON KAUAI, 2 TO
5 INCHES ON OAHU AND MAUI COUNTY, AND AROUND 2 INCHES ON THE BIG
ISLAND. THE POTENTIAL FOR FLOODING REMAINS THROUGH TUESDAY, AND
A FLOOD WATCH IS IN EFFECT FOR THE ENTIRE STATE. DUE TO THE AMOUNT
OF RAIN THAT HAS FALLEN ESPECIALLY OVER KAUAI TODAY, ANY HEAVY
SHOWERS COULD TRIGGER QUICK FLASH FLOODING. IT IS POSSIBLE THE
WATCH MAY NEED TO BE EXTENDED INTO TUESDAY NIGHT OR WEDNESDAY
DEPENDING ON THE LINGERING RAIN BANDS ACROSS THE STATE IN THE WAKE
OF LOWELL AS GUIDANCE SUGGESTS. HOWEVER, WILL HOLD OFF ANY UPDATE
TO THE WATCH AT THIS TIME.
HURRICANE LOWELL IS EXPECTED TO BRING ADDITIONAL RAIN TO THE
ISLANDS THROUGH WEDNESDAY MORNING WITH 4 TO 8 INCHES, ISOLATED 12
INCHES ACROSS KAUAI. OAHU AND MAUI COUNTY, 2 TO 5 INCHES,
ISOLATED 10 INCHES. BIG ISLAND, 4 TO 8 INCHES, ISOLATED 12 INCHES.
THIS RAINFALL MAY PRODUCE SIGNIFICANT FLASH FLOODING AND
MUDSLIDES, ESPECIALLY ACROSS KAUAI COUNTY AND SOUTH AND EAST
PORTIONS OF THE BIG ISLAND. ITS IMPORTANT TO NOTE THAT ANY POP UP
THUNDERSTORMS THAT DEVELOP COULD DRAMATICALLY INCREASE TOTAL
RAINFALL AMOUNTS ANYWHERE.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR ALL HAWAII ISLANDS-
HIGH SURF WARNING UNTIL 6 PM HST TUESDAY FOR NIIHAU-KAUAI
LEEWARD-WAIANAE COAST-KAHOOLAWE-MAUI LEEWARD WEST-KONA-KOHALA-
KAUAI SOUTH-EAST HONOLULU-HONOLULU METRO-EWA PLAIN-MOLOKAI
SOUTHEAST-MOLOKAI WEST-MOLOKAI LEEWARD SOUTH-LANAI LEEWARD-LANAI
SOUTH-MAUI CENTRAL VALLEY SOUTH-KIPAHULU-SOUTH MAUI/UPCOUNTRY-
SOUTH HALEAKALA-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST.
HURRICANE WARNING FOR NIIHAU-KAUAI-
TROPICAL STORM WARNING FOR OAHU-
HIGH SURF ADVISORY UNTIL 6 PM HST TUESDAY FOR OLOMANA-KAUAI EAST-
KOOLAU WINDWARD-MOLOKAI WINDWARD-WINDWARD HALEAKALA-BIG ISLAND
EAST-BIG ISLAND NORTH.
HURRICANE WARNING FOR KAUAI NORTHWEST WATERS-KAUAI LEEWARD
WATERS.
TROPICAL STORM WARNING FOR KAUAI WINDWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS.
SMALL CRAFT ADVISORY UNTIL 6 PM HST TUESDAY FOR KAIWI CHANNEL-
MAUI COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD WATERS-MAALAEA
BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD
WATERS-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.
DISCUSSION/HYDROLOGY/FIRE WEATHER...TSAMOUS
AVIATION...SHIGESATO
MARINE...M BALLARD
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