Flash Flood in Hawaii, February 21, 2006

Name: Flash Flood in Hawaii, February 21, 2006
Start: 2006-02-21T00:51
End: 2006-02-21T11:32
Location: Hawaii

February 21, 2006 · NWS HFO · 1 event in 1 county or zone

Heavy showers and isolated thunderstorms caused flash flooding over northern and southern parts of Kauai. The heavy rain caused the Hanalei River to rise rapidly and wash over the Hanalei Bridge.

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

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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.

Heavy showers and isolated thunderstorms caused flash flooding over northern and southern parts of Kauai. The heavy rain caused the Hanalei River to rise rapidly and wash over the Hanalei Bridge. This forced the closure of Kuhio Highway near Hanalei for most of the day on the 21st. In the southern part of the isle near Koloa, two homes were damaged as the Waikomo Stream overflowed its banks. Damage estimates were not available. There were no serious injuries reported.

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 Feb 20, 8:30 PM HST, 4 hours 21 minutes earlier.

Area forecast discussion, Feb 20, 8:30 PM HST, 4 hours 21 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST MON FEB 20 2006

.SYNOPSIS...
A JETSTREAM ACROSS THE ISLANDS WILL KEEP CONDITIONS RIPE FOR
LOCALIZED HEAVY RAINFALL AND ISOLATED THUNDERSTORMS OVERNIGHT. TRADE
WINDS ARE BLOWING NOW...BUT A TROUGH EXPECTED TO FORM EAST OF THE
BIG ISLAND BY MIDWEEK WILL CAUSE WINDS TO WEAKEN AND BECOME
NORTHERLY. HOWEVER...DRIER CONDITIONS ARE EXPECTED TUESDAY INTO NEXT
WEEKEND AS A RIDGE DEVELOPS OVERHEAD. A FRONT IS EXPECTED SUNDAY AND
MONDAY.

&&

.DISCUSSION...
A 130 MPH JETSTREAM BLOWING FROM WEST SOUTHWEST TO EAST NORTHEAST
ACROSS THE MAIN HAWAIIAN ISLANDS CONTINUES TO ENCOURAGE DEEP
CONVECTION ACROSS THE WESTERN HALF OF THE ISLAND CHAIN THIS EVENING.
HEAVY SHOWERS ARE OCCURRING ACROSS THE SOUTHEAST PORTION OF
KAUAI...WITH RADAR-DERIVED RAINFALL RATES IN EXCESS OF 4 INCHES PER
HOUR NOTED NEAR KOLOA. SO FAR THIS EVENING...THE REMAINING ISLANDS
HAVE SEEN FAR LESS ACTIVITY AFTER A FAIRLY BUSY AFTERNOON. SATELLITE
IMAGERY SHOWS AN AREA OF INCREASED LOW CLOUDS AND MOISTURE MOVING
TOWARDS THE SMALLER ISLANDS FROM THE NORTHEAST. WE WILL SEE IF THE
ADDITION OF THIS MOISTURE TRIGGERS AN UPSURGE IN SHOWER ACTIVITY
EAST OF KAUAI TONIGHT. WE WILL EXTEND THE FLOOD WATCH FOR
KAUAI...OAHU AND MOLOKAI UNTIL 4 AM HST TUESDAY.

WE ARE IN THE PROCESS OF CHANGING THE GRIDDED DATABASE TO ACCOUNT
FOR A TROUGH EXPECTED TO DEVELOP EAST OF THE BIG ISLAND AT MIDWEEK
AND FOR A FRONTAL BOUNDARY TO REACH THE ISLANDS LATE NEXT WEEKEND.
SO FAR...THE MAJOR IMPACT THIS TROUGH WILL HAVE WILL BE TO DECREASE
OUR SURFACE WINDS AND SWING THEM TO NORTHERLIES. ZONAL FLOW ALOFT
EXPECTED WEDNESDAY WILL BECOME ANTICYCLONICALLY CURVED BY FRIDAY AS
AN UPPER RIDGE DEVELOPS. MODELS ACTUALLY KEEP THE ISLANDS RATHER DRY
FROM LATE WEDNESDAY INTO NEXT WEEKEND. HOWEVER...A FRONTAL BAND IS
EXPECTED TO REACH THE ISLANDS SUNDAY...STALLING ACROSS THE CENTRAL
ISLANDS MONDAY. GFS75 INCREASES RAINFALL AMOUNTS DURING THIS
TIME...AND INTRODUCES STRONGER POSTFRONTAL NORTHEAST WINDS TO FINISH
THE FORECAST PERIOD.

LATEST WEB CAMS AND OBSERVATIONS FROM SURFACE AND UPPER AIR STATIONS
INDICATE THE THREAT OF CONTINUOUS DENSE FOG ON THE BIG ISLAND
SUMMITS HAS PASSED. THEREFORE...THE DENSE FOG ADVISORY IS CANCELLED
EFFECTIVE 815 PM HST.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 AM TUESDAY FOR KAUAI OAHU AND MOLOKAI.
&&

POWELL

In the hours before

Local storm report, Feb 20, 9:00 PM HST, 3 hours 51 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
900 PM HST MON FEB 20 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0807 PM     FLASH FLOOD      WAILUA                  22.06N 159.34W
02/20/2006                   KAUAI IN KAUAI     HI   LAW ENFORCEMENT

            LOOP ROAD CLOSURE, WAILUA HOMESTEADS

0807 PM     FLASH FLOOD      2 S KALAHEO             21.89N 159.53W
02/20/2006                   KAUAI IN KAUAI     HI   LAW ENFORCEMENT

            WAHA RD NOT PASSABLE

0807 PM     FLASH FLOOD      5 S LIHUE               21.90N 159.35W
02/20/2006                   PHZ113             HI   LAW ENFORCEMENT

            HEAVY RUNOFF NEAR PUO.

0807 PM     FLASH FLOOD      KAPAA                   22.10N 159.35W
02/20/2006                   KAUAI              HI   LAW ENFORCEMENT

            KEAPANA BRIDGE CLOSURE DUE TO FLOODING

&&

HFO

Local storm report, Feb 20, 10:12 PM HST, 2 hours 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
1012 PM HST MON FEB 20 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1010 PM     FLASH FLOOD      LIHUE                   21.98N 159.35W
02/20/2006                   KAUAI              HI   EMERGENCY MNGR

            ALL ROADS AND BRIDGES ARE NOW OPEN ON KAUAI.

&&

NH

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Kauai

When: February 21, 12:51 AM HST to 11:32 AM HST
Where: Kauai County, Hanalei
Reported by: LAW ENFORCEMENT
Coordinates: 22.200, -159.500

What these are

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 2006 Every state in 2006 This day in weather history Warnings in Hawaii, February 2006

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: 5493099.