A weak tornado formed over leeward Oahu and dissipated in short order. It likely formed along the sea breeze convergence zone in that part of the isle.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS HFO wrote it up.
A weak tornado formed over leeward Oahu and dissipated in short order. It likely formed along the sea breeze convergence zone in that part of the isle. No serious property damage or injuries were reported.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Honolulu, HI wrote its last area forecast discussion before the first event at Apr 23, 10:05 AM HST, 4 hours 51 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 1005 AM HST THU APR 23 2015 .SYNOPSIS... MODERATE TO LOCALLY BREEZY EAST TO SOUTHEAST WINDS WILL PREVAIL ACROSS THE STATE THROUGH FRIDAY. SHOWERS WILL BE MOST COMMON ACROSS WINDWARD AND SOUTHEAST SLOPES...BUT WILL AFFECT SOME LEEWARD AND INTERIOR AREAS AT TIMES AS WELL. THE SOUTHEAST WINDS WILL SPREAD VOLCANIC HAZE ACROSS THE SMALLER ISLANDS THROUGH THE REST OF THIS WEEK. WINDS WILL WEAKEN AND SHIFT TOWARD THE SOUTH AHEAD OF AN APPROACHING FRONT THIS WEEKEND. THE GRADUALLY WEAKENING FRONT IS FORECAST TO MOVE SLOWLY DOWN THE ISLAND CHAIN OVER THE WEEKEND...ACCOMPANIED BY MORE WIDESPREAD CLOUDS AND SHOWERS. BREEZY TRADE WINDS ARE EXPECTED AFTER THE FRONT PASSES...WITH MOISTURE ASSOCIATED WITH THE DISSIPATING FRONT FUELING TRADE WIND SHOWERS. && .DISCUSSION... SURFACE ANALYSIS SHOWS A 1031 MB HIGH CENTERED ABOUT 1100 MILES NE OF THE ISLANDS...WITH A GALE LOW ABOUT 900 MILES TO THE NW. A SLOW MOVING COLD FRONT LIES ACROSS THE NW HAWAIIAN ISLANDS ABOUT 550 MILES NW OF KAUAI. LAYERED CLOUDS WITH EMBEDDED THUNDERSTORMS EXTEND A FEW HUNDRED MILES E OF THE FRONT...AND LIE JUST NW OF THE HAWAIIAN OFFSHORE WATERS. ALOFT...A HIGHLY AMPLIFIED PATTERN PREVAILS OVER THE CENTRAL NORTH PACIFIC...WITH A CLOSED LOW NORTHWEST OF THE ISLANDS CENTERED NEAR 29N 169W. WHILE THIS LOW ALOFT IS SUPPORTING THE NEARBY SURFACE LOW...A STRONG NORTH-SOUTH ORIENTED RIDGE ALOFT ALONG 148W IS SUPPORTING THE SURFACE HIGH. LOCALLY...12Z SOUNDINGS SHOW THAT THE ATMOSPHERE OVER THE W END OF THE ISLAND CHAIN IS BEING INFLUENCED BY THE PROXIMITY OF THE LOW...WITH AN ELEVATED INVERSION BASED AROUND 10K FEET AND PWAT OF 1.26 INCHES...WHILE THE 12Z HILO SOUNDING SHOWS A MORE TYPICAL INVERSION HEIGHT OF 7K FEET. THE EXPECTATION FOR TODAY IS THAT SEA BREEZE CONVERGENCE WILL FUEL CLOUD AND SHOWER DEVELOPMENT OVER ISLAND INTERIORS FROM OAHU TO MAUI...WHILE THE ESE FLOW NEAR THE BIG ISLAND DELIVERS CLOUDS AND A FEW SHOWERS TO WINDWARD AND SE SLOPES...AND THE PREVAILING S WINDS NEAR KAUAI DELIVER PASSING CLOUDS AND A FEW SHOWERS. THE ONGOING SE FLOW REGIME...WHICH IS FORECAST TO CONTINUE THROUGH FRIDAY...IS NOTORIOUSLY DIFFICULT FOR ANTICIPATING CLOUD AND SHOWER COVERAGE...AS WELL AS LOW-LEVEL WINDS...ON THE SMALLER ISLANDS. THIS IS DUE TO THE FACT THAT THE SMALLER ISLANDS LIE IN THE SHADOW OF THE BIG ISLAND...AND EDDIES AND PLUMES DEVELOPING TO THE LEE OF THE BIG ISLAND/MAUI/MOLOKAI CAN SIGNIFICANTLY IMPACT WEATHER OVER DOWNSTREAM AREAS. ONE SUCH EDDY IS CURRENTLY SEEN...VIA RADAR ANIMATIONS... ROTATING ANTICYCLONICALLY OVER WATERS S OF OAHU...AND THE FLOW ASSOCIATED WITH THIS EDDY WAS RESPONSIBLE FOR BRINGING A SHORT-LIVED BOUT OF MODERATE TO HEAVY SHOWERS TO S AND SE OAHU THIS MORNING. THIS TYPE OF WIND REGIME HAS HISTORICALLY LED TO BOUTS OF ANCHORED SHOWERS ALONG THE WINDWARD SIDE OF THE KOOLAU RANGE ON OAHU...WITH AN OVERNIGHT EVENT LEADING TO LOCALIZED FLOODING AS OVER 8 INCHES OF RAIN WAS RECORDED AT PUNALUU PUMP. WHILE THESE TERRAIN-ANCHORED SHOWERS ARE SENSITIVE TO DIFFICULT-TO-FORECAST FLUCTUATIONS IN THE LOW-LEVEL WIND DIRECTION...THE POTENTIAL FOR THIS TO RE-OCCUR WILL PERSIST INTO SATURDAY. LATEST MODEL GUIDANCE IS REASONABLY CONSISTENT WITH THE ONGOING FORECAST PHILOSOPHY...ESPECIALLY IN THE HANDLING OF THE VIGOROUS CLOSED LOW ALOFT CENTERED TO THE NW. IT WILL MOVE VERY SLOWLY S AND THE ASSOCIATED FRONTAL BOUNDARY WILL MOVE LITTLE INTO FRIDAY. EXPECT LITTLE CHANGE LOCALLY...WITH MODERATE TO LOCALLY BREEZY EAST WINDS NEAR THE BIG ISLAND VEERING TO THE SOUTHEAST AROUND OAHU AND KAUAI. SHOWERS DURING THIS TIME SHOULD FOCUS MOSTLY ON WINDWARD AND SOUTHEAST FACING SLOPES...BUT MAY ALSO AFFECT SOME LEEWARD AND INTERIOR AREAS AT TIMES. FOR THE WEEKEND...THE DEEP CUT-OFF LOW WILL BE EJECTED TO THE ENE... AND AS IT DOES SO...IT/S ASSOCIATED SURFACE FRONT WILL MOVE ACROSS THE AREA FROM THE NW WHILE WEAKENING. MODELS KEEP THE PRIMARY MID LEVEL COLD POOL AND STRONGEST FORCING WELL N OF THE ISLANDS...WHICH SHOULD PREVENT ANY THUNDERSTORM DEVELOPMENT LOCALLY. HOWEVER...A BAND OF ENHANCED SHOWER ACTIVITY SEEMS LIKELY TO BE PRESENT ALONG AND AHEAD OF THE FRONT. WITH MOISTURE DEPTH AS HIGH AS 10 KFT... LOCALLY HEAVY SHOWERS ARE POSSIBLE. WHILE THERE ARE SOME MINOR TIMING DIFFERENCES BETWEEN THE LATEST GFS/ECMWF/CMC/NAVGEM RUNS... THEY ARE SUFFICIENTLY SIMILAR TO HAVE A FAIR AMOUNT OF CONFIDENCE. THE FORECAST CALLS FOR THE RELATIVELY SLOW-MOVING FRONT TO MOVE ACROSS KAUAI SATURDAY NIGHT...AND OAHU ON SUNDAY. THERE HAVE BEEN SOME CHANGES IN RECENT MODEL RUNS WITH RESPECT TO HOW FAR SE THE FRONT WILL MOVE DOWN THE ISLAND CHAIN. WHEREAS PREVIOUS RUNS INDICATED THE ASSOCIATED MOISTURE AXIS WOULD STALL NEAR MAUI COUNTY ON SUNDAY...LATEST GFS AND ECMWF RUNS NOW INDICATE THE FRONT WILL MOVE TO MAUI COUNTY BY SUNDAY NIGHT...AND THE BIG ISLAND ON MONDAY. HIGH PRESSURE WILL BUILD NW AND N OF THE AREA AS THE DEEP LAYER LOW DEPARTS...AND MODELS ARE INDICATING MOISTURE ASSOCIATED WITH THE DISSIPATED FRONT WILL FUEL ENHANCED TRADE WIND SHOWERS EARLY NEXT WEEK. && .AVIATION... VFR CONDITIONS PREVAIL AT MOST TAF SITES WITH OCCASIONAL MVFR CONDITIONS OCCURING AT PHLI AND PHTO DUE TO LOW CLOUDS. EXPECT THESE CONDITIONS TO PREVAIL THROUGH THIS AFTERNOON. SOME MVFR CONDITIONS MAY ALSO OCCUR LATER TODAY OVER INTERIOR AND MOUNTAIN AREAS DUE TO LOW CLOUDS AND SHRA. AIRMET TANGO REMAINS POSTED W AND NW OF MOUNTAIN RANGES. EXPECT THESE CONDITIONS TO CONTINUE THROUGH THIS AFTERNOON. AIRMET SIERRA MAY NEED TO BE POSTED LATER TODAY AS CLOUD COVERAGE IS EXPECTED TO INCREASE OVER THE MOUNTAINS THIS AFTERNOON. && .MARINE... A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH TODAY FOR E FACING SHORES OF MOST ISLANDS...AND S FACING SHORES OF ALL ISLANDS. LATEST OBSERVATIONS INDICATE THE SSW SWELL IS DIMINISHING FROM A PEAK THAT MOVED THROUGH YESTERDAY...AND THAT ADVISORY SHOULD BE ALLOWED TO EXPIRE THIS AFTERNOON. ALTHOUGH LOCAL WINDS WILL BE OUT OF THE SE TO S OVER THE NEXT COUPLE OF DAYS...ESPECIALLY OVER THE W END OF THE ISLAND CHAIN...A LONG FETCH OF FRESH TO STRONG E WINDS WILL REMAIN E OF THE ISLANDS. THE EXPECTATION THEREFORE IS THAT THE HIGH SURF ADVISORY FOR E FACING SHORES WILL NEED TO BE EXTENDED IN TIME. SMALL SWELLS FROM THE NW WILL CONTINUE THROUGH THE WEEKEND. A LARGE NNW SWELL IS POSSIBLE FROM LATE SUNDAY THROUGH MONDAY...WITH PEAK SURF HEIGHTS POTENTIALLY REACHING ADVISORY LEVELS...ESPECIALLY ON N FACING SHORES. A SMALL CRAFT ADVISORY REMAINS IN PLACE FOR MOST WINDWARD WATERS AND CHANNELS BETWEEN THE ISLANDS. AN OVERNIGHT ASCAT PASS SAMPLED ONLY THE E EDGE OF THE HAWAIIAN COASTAL WATERS...BUT FOUND A LARGE AREA OF 25 KT WINDS N OF THE BIG ISLAND AND NE OF MAUI...WITH SOME WINDS NEAR 30 KT OFF THE HAMAKUA COAST. THIS DATA ALONG WITH MODEL GUIDANCE INDICATE THAT NO CHANGES ARE NEEDED TO THE EXISTING SMALL CRAFT ADVISORY...WHICH REMAINS POSTED THROUGH 6 PM FRIDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR EAST FACING SHORES OF KAUAI OAHU MOLOKAI MAUI AND BIG ISLAND. HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR SOUTH FACING SHORES OF ALL ISLANDS. SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR OAHU WINDWARD WATERS-KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-PAILOLO CHANNEL- ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS. && DISCUSSION/MARINE...BIRCHARD AVIATION...BURKE
The Molokai radar (PHMO), 93 km away, was scanning. The volume nearest the first event began at 00:54 UTC.
1 tornado. Local standard time, as filed.
A weak tornado formed in leeward Oahu and dissipated without incident.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Hawaii in 2015Every state in 2015This day in weather historyThe tornado archive for Hawaii, 2015Warnings in Hawaii, April 2015
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 565974.