A low pressure system in the upper levels of the atmosphere brought unstable conditions which allowed thunderstorms and heavy rain to develop. As a result of the thunderstorms and heavy rain, flooding and flash flooding was observed over portions of the Islands.
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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 low pressure system in the upper levels of the atmosphere brought unstable conditions which allowed thunderstorms and heavy rain to develop. As a result of the thunderstorms and heavy rain, flooding and flash flooding was observed over portions of the Islands.
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 May 10, 3:28 PM HST, 2 minutes earlier.
Area Forecast Discussion National Weather Service Honolulu HI 328 PM HST Fri May 10 2024 .SYNOPSIS... The threat for strong to severe thunderstorms and heavy rainfall will continue across the state tonight as a strong upper level disturbance settles southward into the area. Although the thunderstorm potential decreases this weekend, plenty of moisture lingering combined with afternoon sea breezes and a broad surface trough nearby will support afternoon showers over interior and leeward areas each day. The wet pattern could continue through the latter half of next week as another upper disturbance approaches. && .DISCUSSION... Water vapor imagery showed broad upper troughing over the region with a strong shortwave low digging southeastward into the area. The associated surface trough is located over Kauai with low-level convergent flow driving the potential for heavy showers and embedded thunderstorms later today. MUCAPES of 1000 to 2000 J/Kg combined with effective deep layer shear values of 35 to 45 knots will support a few strong to severe thunderstorms and locally heavy rainfall that could lead to flash flooding. As a result, a Flood Watch remains in effect for the entire state through tonight. Daytime heating brought sea breeze convergence over the islands this afternoon resulting in showers and thunderstorms over most islands today that will linger into this evening. The focus will shift to Big Island and Maui County later tonight into Saturday morning, where the high shear potential sets up for more organized convection capable of producing severe thunderstorms (strong winds, hail, water and land spouts). However, have added a slight chance of thunderstorms for tonight across the western half of the state given the current proximity of the low and radar activity. A Winter Storm Warning and High Wind Warning are also posted for Big Island summits due to the high elevation impacts from this system. Guidance shows the upper low beginning to weaken as it lifts off to the northeast this weekend into early next week, which will support a diminishing likelihood of thunderstorms. The surface trough will fade and gentle to trades will ease back in by the end of the day Saturday before weakening again Sunday. The rainfall chances will likely linger as the aforementioned broad surface trough remains over or nearby to the west Sunday through next week. Expect the light to moderate east to southeast low- level flow to persist, which will allow the land and sea breeze regime to hold for most areas. This combined with a sufficient amount of moisture will keep the rainfall chances up each day, especially through the afternoon and early evening periods over interior/leeward areas with the sea breezes. The wet pattern could persist through the second half of the week as another upper low drops southward into the area drawing up deep tropical moisture and southerly flow over the state. && .AVIATION... A broad surface trough and upper level disturbance are moving southeast across the state. This will bring SHRA and TS activity through the rest of today into the overnight hours. Expect periods of MVFR conds with occasional IFR conds possible under heavier SHRA/TS. AIRMET Sierra remains in effect for mtn obsc across the smaller islands and windward Big Island. AIRMET Tango may become necessary for moderate mid to upper level turbulence as the upper level disturbance moves across the state. AMD NOT SKED for PMDY continues due to equipment issues, with no timeline for restoration. && .MARINE... Strong to severe thunderstorms will remain possible tonight through Saturday morning as an unusually strong upper level disturbance moves across the area. Any thunderstorms that develop will have the potential to produce strong wind gusts, hail, and frequent lightning. Marine interests should continue to monitor for Special Marine Warnings that may be issued through Saturday. Additionally, as a surface trough that is currently in the Kauai Channel strengthens and moves across the island chain, light and variable winds will prevail across local waters, except for within thunderstorm areas. Light to moderate easterly trade winds will begin building back into the region on on Sunday. A long-lived south swell will affect the islands into the weekend. Recent observations show that surf along south facing shores has fallen just below advisory levels, so the High Surf Advisory has been cancelled. Although the swell will continue for the next several days, surf should slowly trend down as the period declines. Another series of overlapping, long-period south swells will give another sizable boost to south shore surf Wednesday through late next week. A small, reinforcing short-period north-northwest swell is building in late this afternoon. This swell will increase north and west shore surf this evening through Saturday morning, then decline later Saturday into Sunday. A new small, long-period northwest swell will build Sunday night, giving north shore surf a boost early next week. Surf along east facing shores will be well below normal levels through the middle of next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Flood Watch through late tonight for all Hawaiian Islands. High Wind Warning until 6 AM HST Saturday for Big Island Summits. Winter Storm Warning until 6 AM HST Saturday for Big Island Summits. && DISCUSSION...Foster AVIATION...Walsh MARINE...Thomas
The Kamuela/Kohala Apt radar (PHKM), 84 km away, was scanning. The volume nearest the first event began at 01:30 UTC.
6 flash flood, 2 flood, 1 debris flow. Local standard time, as filed.
Waianuenue and Kamehameha Avenues were closed in both directions due to flooding.
All lanes were closed at the Kawaihae Road and Queen Kaahumanu Hwy intersection due to flooding at the bridges on both sides of the intersection.
Fast water was flowing over rock walls and over streets.
According to the Department of Transportation and social media, flooding was reported on Kamehameha Hwy. In addition, the Waiahole region was flooded due to heavy rain.
According to the Star Advertiser, the H-3 off-ramp onto Kamehameha Highway (Kaneohe) was closed after a dozen vehicles were reportedly stalled on flooded roadway.
Flash flooding was reported on Kaneohe Bay Drive after the pier. Water, rocks, and debris were reported on the road.
According to the Star Advertiser, the right lane of the Pali Highway after the eastern tunnel exit was closed due to a landslide.
Kamehameha Highway was closed in both directions at Waikane Valley Road due to flooding. Also the town-bound portion of Kalanianaole Highway was closed near Kapaa Quarry Road due to a landslide.
Auloa Road was closed from Castle Junction to Maunawili due to flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Hawaii in 2024Every state in 2024This day in weather historyWarnings in Hawaii, May 2024
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: 1184421, 1184422, 1184423, 1184424, 1184433, 1184431, 1184436, 1184439, 1184443.