A trough over the state, in combination with plentiful moisture, caused a downpour over the island of Oahu. Thunderstorms formed over the isle during the late morning and early afternoon hours.
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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 trough over the state, in combination with plentiful moisture, caused a downpour over the island of Oahu. Thunderstorms formed over the isle during the late morning and early afternoon hours. Flash flooding then occurred over leeward sections. The cost of damages was not available. No serious 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 Mar 31, 9:48 AM HST, 2 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Honolulu HI 948 AM HST Sat Mar 31 2018 .SYNOPSIS... Mostly cloudy, hazy, and somewhat humid conditions under light southerly winds will persist over most of the state this weekend. A front stalling near Kauai will produce wet weather with a few heavy showers and thunderstorms over the western half of the state, while the eastern half of the island chain experiences spotty rainfall. The unusual early April run of hazy and somewhat humid kona winds will extend into the first half of the work week, with periods of wet and unsettled weather expected mainly from Kauai to Maui. On Thursday, a cold front will sweep down the island chain, spreading showers across each island through early Friday. && .DISCUSSION... A front approaching Kauai will produce wet conditions over the western half of the state today, while a cloudy, hazy and somewhat humid southeast to south low level flow sets up state- wide. The ragged front was re-energized overnight by a digging upper level trough currently centered over Kauai. This feature has been producing isolated thunderstorms near Kauai and is rapidly enhancing showers between Kauai and Oahu. Issued an update to expand thunderstorm chances from Kauai to cover Oahu and parts of Maui County. Although there could be a brief thunderstorm on Maui this afternoon, the eastern half of the state will likely experience spotty shower activity over interior sections. Chances for showers and thunderstorms will drop off dramatically during the evening as the weakening upper trough swings east of the state. Deeper moisture along the ragged front is expected to stall northwest of Kauai, and as upper level forcing diminishes, shower activity is expected decrease, with the highest rainfall chances near Kauai. The somewhat humid southeast to south low level flow will hold, leading to light land breezes. While the thick mid to upper level clouds will move off to the east, another batch of high clouds will be moving in from the northwest later tonight. Mostly cloudy, hazy, and somewhat humid conditions will dominate on Sunday, as the state stays under light southeast to south winds. With the front remaining stalled northwest of Kauai, the deepest moisture will remain over the western end of the state. While spotty showers are expected to develop over all islands during the afternoon, the greatest chances for rainfall remain near Kauai. Conditions will remain slightly unstable with no inversion, but thunderstorms do not appear likely at this time. Monday through Wednesday, we remain in another interesting weather pattern for next week with a stationary frontal boundary lingering just northwest of the islands and a combination Polar and Subtropical Jet streams aloft. A second low pressure system will move across the Central Pacific on Monday and Tuesday with upper level forcing along the stationary front causing a low pressure system to develop just west of the islands. The pressure gradients and wind directions will veer towards the south and southwest in response to this developing low. The low center will track northeastward brushing past Kauai on Tuesday evening increasing shower activity across the islands through Wednesday as it passes. This unusual and complicated weather pattern brings some uncertainty in the onset timing of rain showers for each island. We will likely make additional adjustments to the precipitation chances, intensity and timing as the forecast time period gets closer. That said, Kauai and Oahu will likely see the highest shower activity with heavy rainfall and a potential threat for flash flooding from Tuesday into Wednesday as the low pressure system passes through the region. A flash flood watch may be needed for this time period. On Thursday and Friday, colder air moving into the Central Pacific from the northwest will help to push this stalled front through the islands in the latter half of the week. Extensive clouds and numerous showers are expected for areas within the frontal band. The latest model projections show the cold front passing through Kauai early Thursday morning, reaching Oahu by late morning, passing through Maui County from Thursday afternoon to evening, and stalling out once again near the Big Island on Friday. Meanwhile, a high pressure center moves eastward across the Central Pacific bringing a brief period of drier and more stable air to the northern half of the state. Long range forecast guidance continues to hint that the shifting ridge pattern may drive the stalled front back towards the central and northern islands next weekend. Stay tuned for updates and keep watching for the latest forecast changes on your favorite local TV station or from our website at weather.gov/hawaii && .AVIATION... VFR conditions prevail at all TAF sites but brief MVFR conditions are possible over PHLI...PHNL and PHJR today in SHRA/TSRA. Airmet Sierra is posted for mountain obscuration over Kauai and may need to be expanded to Oahu later this morning or this afternoon. Airmet Zulu is posted from Kauai to Maui for tempo light icing between FL150 and FL250. && .MARINE... The current west-northwest swell is producing low end advisory surf for north and west facing shores of the smaller islands this morning, so the High Surf Advisory continues for those shores. The swell is expected to gradually trend downward tonight through Monday. Light to moderate winds are expected to continue over the next couple of days, along with seas below 10 ft. As such, no Small Craft Advisories are anticipated. A front approaching from the northwest is bringing showers, some with heavy rain, and isolated thunderstorms to the western half of the island chain and surrounding waters today. Lightning and sudden wind gusts are possible near the heavy showers and thunderstorms. See the latest Oahu Surf Discussion (SRDHFO) for additional details on surf and swell. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 PM HST this evening for north and west facing shores of Niihau, Kauai, Oahu, and Molokai, and for north facing shores of Maui. && DISCUSSION...Wroe/Bohlin AVIATION...Burke MARINE...M Ballard
The Molokai radar (PHMO), 88 km away, was scanning. The volume nearest the first event began at 22:08 UTC.
1 flash flood. Local standard time, as filed.
Flooding occurred in at least two homes on the south side of Fort Weaver Road between Parish Drive and Hapalua Street. A drainage canal had become clogged with debris, causing water to spill out of the canal into the homes.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Hawaii in 2018Every state in 2018This day in weather historyWarnings in Hawaii, March 2018
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: 739620.