Flash Flooding and Heavy Rain in Hawaii, July 19 to 22, 2014

Name: Flash Flooding and Heavy Rain in Hawaii, July 19 to 22, 2014
Start: 2014-07-19T14:18
End: 2014-07-22T19:06
Location: Hawaii

July 19 to 22, 2014 · NWS HFO · 9 events in 4 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 9

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.

What happened

The episode as NWS HFO wrote it up.

An upper trough near the Hawaiian Islands acted on remnant moisture from former Tropical Storm Wali to generate heavy showers and thunderstorms. The rain was intense enough to produce flash flooding in windward parts of Oahu and in windward West Maui. Strong winds accompanied the precipitation, and blew down trees and damaged homes. Also, a man, snorkeling with a group, died when he succumbed to strong winds and high waves that battered the area off Maui on the 20th.

The cost of damages to homes and other structures, and other physical property, was not available.

What forecasters said that day

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 Jul 19, 10:00 AM HST, 4 hours 18 minutes earlier.

Area forecast discussion, Jul 19, 10:00 AM HST, 4 hours 18 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST SAT JUL 19 2014

.SYNOPSIS...
DEEP TROPICAL MOISTURE IS SPREADING ACROSS THE STATE FROM THE
SOUTHEAST...AND WILL BRING THE POTENTIAL FOR HEAVY RAIN TO THE
ISLANDS THROUGH MONDAY. THE HEAVY RAIN COULD PRODUCE FLASH FLOODING
AND THERE IS THE SLIGHT CHANCE FOR THUNDERSTORMS. A MORE STABLE
TRADE WIND WEATHER PATTERN IS EXPECTED TO RETURN BY THE MIDDLE OF
THE NEW WEEK.

&&

.DISCUSSION...
THE DEEP TROPICAL MOISTURE ASSOCIATED WITH THE REMNANTS OF WHAT WAS
ONCE TROPICAL DEPRESSION WALI ARE FOUND ON RADAR SOUTHEAST OF THE
BIG
ISLAND THIS MORNING. RAIN BEGAN MOVING OVER THE BIG ISLAND
OVERNIGHT...BUT RAINFALL TOTALS REMAIN ON THE LIGHTER SIDE AS OF 8
AM. THE DEEPER LAYERED MOISTURE IS EXPECTED TO MOVE OVER THE BIG
ISLAND TODAY...AND SPREAD OVER MAUI COUNTY. AS SUCH THE FLASH FLOOD
WATCH WAS ISSUED FOR THOSE AREA DURING THE PRE-DAWN FORECAST
PACKAGE...AND REMAINS IN EFFECT.

AN UPPER LEVEL LOW IS ABOUT 330 MILES NORTHWEST OF KAUAI AT 8 AM.
UPPER LEVEL CLOUDS ARE FOUND MOVING OVER THE BIG ISLAND FROM THE
SOUTHWEST DUE TO THE RESULTING UPPER LEVEL JET OVER THE ISLANDS. THE
MODELS ARE IN GOOD AGREEMENT WITH THE UPPER LOW MOVING STEADILY TO
THE WEST THROUGH MONDAY NIGHT BEFORE BEGINNING TO DISSIPATE. AS THIS
UPPER SYSTEM MOVES TO THE WEST.

THE DEEP MOISTURE MENTIONED ABOVE WILL MOVE ACROSS THE ISLAND CHAIN
THROUGH MONDAY NIGHT. THE MODELS ARE IN GOOD AGREEMENT WITH
PRECIPITABLE WATER /PW/ VALUES OF 1.9 INCHES SPREADING OVER THE
ISLANDS TODAY...AND LINGERING THROUGH MONDAY NIGHT...BEFORE STARTING
TO LIGHTEN UP. NORMAL PW VALUES FOR JULY ARE AROUND 1.30 INCHES.

HIGH PRESSURE FAR NORTH OF THE ISLANDS WILL MAINTAIN A EASTERLY
BACKGROUND FLOW THROUGH THE FORECAST PERIOD. AS A RESULT...RAINFALL
TOTALS ARE EXPECTED TO BE HIGHER OVER WINDWARD AREAS THROUGH MONDAY
NIGHT. A GRADUAL RETURN TO MORE TYPICAL TRADE WIND WEATHER IS
EXPECTED TUESDAY AND WEDNESDAY...BUT MAY BE SHORT LIVED AS THE
MODELS SHOW ANOTHER SLUG OF TROPICAL MOISTURE MOVING INTO THE
ISLANDS FROM THE SOUTHEAST DURING THE SECOND PART OF NEXT WEEKEND.

&&

.AVIATION...
ABUNDANT LOW LEVEL MOISTURE ASSOCIATED WITH REMNANTS OF TROPICAL
DEPRESSION WALI RIDING THE TRADE WINDS INTO THE STATE TODAY. THE BIG
ISLAND AND MAUI ARE CURRENTLY SEEING THE INFLUX OF CLOUDS WHICH
WILL PROGRESS WEST ACROSS THE REST OF THE ISLAND CHAIN THROUGH
TONIGHT. NUMEROUS MVFR/IFR CEILINGS AND VISIBILITIES EXPECTED MOSTLY
ALONG WINDWARD AND MOUNTAIN AREAS BUT SPREADING TO SOME LEEWARD
AREAS AS WELL. THUS MOUNTAIN OBSCURATIONS EXPECTED TO EXPAND FROM
THE BIG ISLAND AND MAUI TO THE OTHER ISLANDS IN THE NOT TOO DISTANT
FUTURE.

CURRENTLY ONLY LIGHT ICING BEING REPORTED WITH MOISTURE BEING JUST
BELOW THE FREEZING LEVEL. BUT MORE ICING POSSIBLE AS THE REMNANT
MOISTURE CONTINUES TO MOVE WEST BELOW AND UPPER TROUGH ANCHORED JUST
WEST OF KAUAI.

&&

.MARINE...
WINDS ARE JUST BELOW SMALL CRAFT ADVISORY /SCA/ CRITERIA TODAY IN
THE WINDER LOCATIONS AROUND MAUI AND THE BIG ISLAND. THE WINDS ARE
EXPECTED TO REMAIN BELOW CRITERIA THROUGH MONDAY NIGHT...BEFORE
TRENDING UPWARDS. AN SCA MAY BE NEEDED FOR THOSE WINDIER LOCATIONS
AS EARLY AS TUESDAY NIGHT OR WEDNESDAY.

A SMALL...SHORT-PERIOD NORTHEAST SWELL IS EXPECTED TO PERSIST
THROUGH MONDAY. A SMALL SOUTH SWELL TODAY WILL SHIFT TO THE
SOUTH-SOUTHEAST AND GRADUALLY DIMINISH THROUGH TUESDAY.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH IN EFFECT THROUGH MONDAY AFTERNOON FOR THE BIG
ISLAND AND MAUI COUNTY.

FLASH FLOOD WATCH WILL BE IN EFFECT FROM 6PM HST THIS EVENING
THROUGH MONDAY AFTERNOON FOR OAHU AND KAUAI COUNTY.

&&

DISCUSSION/MARINE...M BALLARD
AVIATION...FUJII

The radar

The Kamuela/Kohala Apt radar (PHKM), 38 km away, was scanning. The volume nearest the first event began at 00:16 UTC.

Open the radar archive at this moment

Event by event

7 heavy rain, 2 flash flood. Local standard time, as filed.

Heavy Rain, Hawaii

When: July 19, 2:18 PM HST to 3:45 PM HST
Where: Hawaii County, 3.77 mi S of Paauhau to 0.79 mi WNW of Glenwood
Reported by: Official NWS Observations
Coordinates: 20.026, -155.429

Heavy Rain, Honolulu

When: July 19, 9:41 PM HST to July 20, 12:21 AM HST
Where: Honolulu County, 1.23 mi E of Wheeler Afb to 0.03 mi ENE of Barbers Pt Housing
Reported by: Official NWS Observations
Coordinates: 21.479, -158.011

Flash Flood, Honolulu

When: July 20, 12:55 AM HST to 8:39 AM HST
Where: Honolulu County, 1.82 mi ESE of Waikane to 2.13 mi E of Waikane
Cause: Heavy Rain
Reported by: Emergency Manager
Coordinates: 21.495, -157.852

The Honolulu Police closed Kamehameha Highway near Waikane on the windward side of Oahu because of flooding. Several vehicles stalled in the area in the high water.

Heavy Rain, Maui

When: July 20, 3:44 AM HST to 6:34 AM HST
Where: Maui County, 0.42 mi SSW of Halawa Valley to 1.74 mi WNW of Kamalo
Reported by: Official NWS Observations
Coordinates: 21.164, -156.752

Heavy Rain, Kauai

When: July 20, 5:43 AM HST to 8:39 AM HST
Where: Kauai County, 2.62 mi NNW of Anahola to 0.47 mi W of Hanapepe
Reported by: Official NWS Observations
Coordinates: 22.156, -159.312

Flash Flood, Maui

When: July 20, 9:20 AM HST to 10:18 AM HST
Where: Maui County, 0.3 mi SSE of Kahakuloa to 0.33 mi SSE of Kahakuloa
Cause: Heavy Rain
Reported by: Broadcast Media
Coordinates: 20.996, -156.548

Flooding in Kahakuloa Stream inundated the bridge in Kahakuloa town in windward West Maui and briefly closed Kahekili Highway in that area.

Heavy Rain, Maui

When: July 20, 3:39 PM HST to 10:21 PM HST
Where: Maui County, 1.19 mi SE of Honokahua to 1.6 mi SSW of Hana
Reported by: Official NWS Observations
Coordinates: 20.987, -156.638

Heavy Rain, Hawaii

When: July 20, 8:07 PM HST to July 21, 1:56 AM HST
Where: Hawaii County, 2.31 mi SW of Ookala to 1.55 mi NNE of Glenwood
Reported by: Official NWS Observations
Coordinates: 20.000, -155.308

Heavy Rain, Hawaii

When: July 22, 5:37 PM HST to 7:06 PM HST
Where: Hawaii County, 4.21 mi SW of Waikii to 7.34 mi NW of Kailua Kona
Reported by: Official NWS Observations
Coordinates: 19.832, -155.709

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Hawaii in 2014 Every state in 2014 This day in weather history Warnings in Hawaii, July 2014

Sources

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: 528457, 528458, 528459, 528460, 528461, 528463, 528480, 528481, 528482.