Flash Flood and Winter Storm in Hawaii, December 9 to 11, 2010

Name: Flash Flood and Winter Storm in Hawaii, December 9 to 11, 2010
Start: 2010-12-09T18:00
End: 2010-12-11T05:53
Location: Hawaii

December 9 to 11, 2010 · NWS HFO · 13 events in 5 counties and zones

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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: 13

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.

A cold front, in combination with an upper trough, brought heavy showers, rain, and thunderstorms to parts of the Aloha State. The systems also generated snow for the summits of Mauna Kea and Mauna Loa on the Big Island of Hawaii. There were no reports of serious injuries. The weather did cause flooding problems for some residents, power and phone outages, and downed trees. The costs of the damages were 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 Dec 9, 4:00 PM HST, 2 hours earlier.

Area forecast discussion, Dec 9, 4:00 PM HST, 2 hours before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU DEC 9 2010

.SYNOPSIS...
SOUTH WINDS WILL INCREASE IN ADVANCE OF A COLD FRONT APPROACHING
FROM THE NORTHWEST. HEAVY SHOWERS AND THUNDERSTORMS NOW OVER AND
NEAR KAUAI AND OAHU WILL SPREAD OVER THE ENTIRE STATE TONIGHT AND
FRIDAY. LOCALLY HEAVY RAINFALL IS POSSIBLE...WHICH COULD RESULT IN
FLASH FLOODING.

&&

.DISCUSSION...
FORTUNATELY...THE HEAVY SHOWERS AND THUNDERSTORMS HAVE STAYED OVER
THE KAUAI CHANNEL WHERE NEXRAD ESTIMATED RAINFALL TOTALS WERE IN
EXCESS OF 21 INCHES AS OF 2 PM. COASTAL WATERS NORTHWEST OF KAUAI
ALSO HAD IMPRESSIVE RAINFALL TOTALS IN EXCESS OF 10 INCHES. THE
ISLANDS HAVE BEEN LUCKY SO FAR...BUT IT WOULD NOT TAKE MUCH TO HAVE
THE HEAVY CONVECTION SHIFT TO OVER LAND. HENCE THE FLASH FLOOD WATCH.

CONVERGENT LOW LEVEL FLOW OUT OF THE SOUTHEAST...SOUTH AND SOUTHWEST
WILL BRING MOIST AIR UP OVER THE ISLANDS THROUGH FRIDAY. THE SOUTH
FLOW IS IN ADVANCE OF A COLD FRONT LOCATED NORTHWEST OF KAUAI. THE
FRONT IS MOVING SLOWLY TO THE SOUTHEAST...AND IS EXPECTED TO REACH
KAUAI FRIDAY NIGHT. IT WILL THEN MOVE DOWN THE ISLAND CHAIN TO EAST
OF THE BIG ISLAND BY SATURDAY NIGHT. THE MOIST AIR WILL SHIFT TO THE
EAST IN ADVANCE OF THE FRONT.

INSTABILITY ASSOCIATED WITH AN UPPER LEVEL TROUGH NORTHWEST OF THE
STATE WILL SET OFF HEAVY SHOWERS AND THUNDERSTORMS IN THE MOIST AIR
AHEAD OF THE FRONT. THE TROUGH IS FORECAST TO MOVE TO THE SOUTHEAST
AND IS EXPECTED TO BE EAST OF THE ISLANDS SATURDAY NIGHT. THE FLASH
FLOOD WATCH PRESENTLY IN EFFECT FOR NIIHAU...KAUAI AND OAHU WILL
EXPAND TO COVER ALL ISLANDS TONIGHT.

WINDS ON THE SUMMITS OF THE BIG ISLAND AND MOUNT HALEAKALA MAY REACH
WIND ADVISORY CRITERIA THIS EVENING. ALSO...WINTER WEATHER
CONDITIONS ARE POSSIBLE OVER THE BIG ISLAND SUMMITS FRIDAY NIGHT
INTO SATURDAY MORNING. A WINTER STORM WATCH HAS BEEN ISSUED FOR THE
POTENTIALLY HEAVY SNOW.

WITH THE FRONT AND THE TROUGH ALOFT EAST OF THE BIG ISLAND SUNDAY...
A SURFACE HIGH PRESSURE WILL MOVE NORTH OF THE STATE AND TRADE WINDS
WILL RETURN. ALSO...A RIDGE ALOFT TRAILING THE TROUGH WILL MOVE OVER
THE ISLANDS FROM THE WEST RESULTING IN A MORE STABLE ATMOSPHERE.

&&

.MARINE...
THE CURRENT LARGE NORTH SWELL WILL GRADUALLY DIMINISH THROUGH THIS
WEEKEND. THE HIGH SURF ADVISORY FOR NORTH AND EAST FACING SHORES
WILL LIKELY BE CANCELED EARLY FRIDAY MORNING.

A MARINE WEATHER STATEMENT HAS BEEN ISSUED FOR HARBOR SURGE IN THE
KAHULUI AND HILO HARBORS DUE TO THE LARGE NORTH SWELL. THE STATEMENT
ALSO ALERTS MARINERS TO THE THREAT OF ADVERSE WEATHER CONDITIONS
ASSOCIATED WITH THE THUNDERSTORMS.

A SMALL CRAFT ADVISORY /SCA/ CONTINUES FOR ALL OF THE COASTAL
WATERS...EXCEPT MAALAEA BAY AND THE BIG ISLAND LEEWARD WATERS DUE TO
THE LARGE NORTH SWELL. SEAS WILL DECREASE BELOW SCA CRITERIA TONIGHT
FOR MOST COASTAL WATERS. HOWEVER...INCREASING SOUTH TO SOUTHWEST
WINDS...AS WELL AS LARGER SEAS DUE TO LOCALLY GENERATED WIND
WAVES...WILL REQUIRE THE SCA TO REMAIN IN EFFECT THROUGH FRIDAY
MORNING FOR THE COASTAL WATERS AROUND KAUAI AND OAHU.

&&

.AVIATION...
WDSPRD TSRA CONTINUE TO AFFECT THE AREA FROM THE KAUAI CHANNEL WWD
WITH PREVAILING MVFR/IFR CIGS AND VIS. LOCAL LIFR CONDITIONS ARE
LIKELY NEAR THE STRONGEST CONVECTION. TOPS ARE EXCEEDING FL500
PRODUCING SEV TURB AS WELL. HAVE FAIR CONFIDENCE IN THE 00Z TAF
CRITICAL PERIOD. HAVE TRIED TO REPRESENT TRENDS IN THE LONGER TERM
GROUPS IN THE TAFS...BUT STILL HAVE LOW CONFIDENCE DUE TO SHORT TERM
DIFFERENCES IN GUIDANCE. ANTICIPATING FURTHER AMDS TO THE TAFS/FA
THROUGH THE PERIOD. WILL DO OUR BEST TO KEEP THE FORECAST
REPRESENTATIVE. SIGMET UNIFORM CONTINUES TO OVERLAP THE AREA AND
WILL LIKELY STICK AROUND FOR QUITE SOMETIME. WDSPRD TSRA EXPECTED TO
PERSIST THRU FRI...TRACKING SLOWLY EWD. AIRMET SIERRA CONTINUES FOR
KAUAI...BUT HAVE BACKED UP THE ONSET FOR OAHU TIL AFT 04Z. WILL FINE
TUNE THIS AS WELL AND TRY TO PIN POINT AT LEAST A WINDOW OF
DEVELOPING CONDITIONS FOR TONNIGHT.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 600 AM HST SATURDAY FOR OAHU KAUAI AND
NIIHAU.

FLASH FLOOD WATCH FROM 600 PM HST TODAY UNTIL 600 AM HST SATURDAY
FOR MOLOKAI...MAUI...LANAI...KAHOOLAWE AND THE BIG ISLAND.

WINTER STORM WATCH IN EFFECT FROM 6 PM FRIDAY EVENING TO 12 PM
SATURDAY AFTERNOON FOR THE SUMMIT AREAS OF MAUNA LOA AND MAUNA KEA.

HIGH SURF ADVISORY UNTIL 600 AM HST FRIDAY MORNING FOR NORTH AND
EAST FACING SHORES OF NIIHAU...KAUAI...OAHU...MOLOKAI...MAUI AND THE
BIG ISLAND.

SMALL CRAFT ADVISORY UNTIL 600 PM HST TODAY FOR MAUI COUNTY WINDWARD
WATERS...MAUI COUNTY LEEWARD WATERS...PAILOLO CHANNEL...ALENUIHAHA
CHANNEL...BIG ISLAND WINDWARD WATERS AND BIG ISLAND SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 600 AM HST FRIDAY FOR THE COASTAL WATERS
AROUND NIIHAU...KAUAI AND OAHU.

&&

CRAIG/DEJESUS

The radar

The Molokai radar (PHMO), 117 km away, was scanning. The volume nearest the first event began at 03:58 UTC.

Open the radar archive at this moment

Event by event

10 heavy rain, 1 thunderstorm wind, 1 flash flood, 1 winter storm. Local standard time, as filed.

Heavy Rain, Honolulu

When: December 9, 6:00 PM HST to December 10, 3:17 AM HST
Where: Honolulu County, 2.38 mi SW of Mokuleia to 0.42 mi E of Hawaii Kai
Reported by: Official NWS Observations
Coordinates: 21.558, -158.209

Thunderstorm Wind, Kauai

When: December 9, 6:35 PM HST to 6:40 PM HST
Where: Kauai County, 4 mi W of Kapaa
Measured: 50 kt (58 mph) estimated gust
Reported by: Public
Coordinates: 22.080, -159.382

A large tree was toppled by thunderstorm winds. The tree then fell on a boat and a shed.

Flash Flood, Kauai

When: December 9, 7:30 PM HST to December 10, 1:11 AM HST
Where: Kauai County, 0.62 mi SSE of Princeville to 0.71 mi SSE of Princeville
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 22.212, -159.476

Heavy rains caused the Hanalei River to rise over its banks along Kuhio Highway at the Hanalei Bridge.

Heavy Rain, Maui

When: December 10, 1:22 AM HST to 4:15 AM HST
Where: Maui County, 2.39 mi NE of Kepuhi to 3.86 mi SE of Kalawao
Reported by: Official NWS Observations
Coordinates: 21.201, -157.220

Heavy Rain, Maui

When: December 10, 2:53 AM HST to 5:40 AM HST
Where: Maui County, 6.35 mi W of Shipwreck Beach to 1.92 mi NE of Manele Harbor
Reported by: Official NWS Observations
Coordinates: 20.903, -157.017

Heavy Rain, Maui

When: December 10, 4:07 AM HST to 6:51 AM HST
Where: Maui County, 0.85 mi ENE of Honokahua to 5.02 mi NW of Koali
Reported by: Official NWS Observations
Coordinates: 21.004, -156.638

Heavy Rain, Maui

When: December 10, 4:17 AM HST to 10:08 AM HST
Where: Maui County, 2.04 mi ENE of Kepuhi to 1.2 mi ENE of Pukoo
Reported by: Official NWS Observations
Coordinates: 21.195, -157.223

Heavy Rain, Honolulu

When: December 10, 4:31 AM HST to 7:24 AM HST
Where: Honolulu County, 2.12 mi SW of Mokuleia to 0.36 mi S of Hawaii Kai
Reported by: Official NWS Observations
Coordinates: 21.558, -158.203

Heavy Rain, Maui

When: December 10, 5:41 AM HST to 8:36 AM HST
Where: Maui County, 6.87 mi W of Shipwreck Beach to 1.66 mi ENE of Manele Harbor
Reported by: Official NWS Observations
Coordinates: 20.903, -157.025

Heavy Rain, Maui

When: December 10, 6:56 AM HST to 3:21 PM HST
Where: Maui County, 1.39 mi S of Honokohau to 1.51 mi NNW of Kaupo
Reported by: Official NWS Observations
Coordinates: 21.000, -156.624

Heavy Rain, Hawaii

When: December 10, 1:03 PM HST to 8:38 PM HST
Where: Hawaii County, 3.09 mi ESE of Mahukona to 2.9 mi ENE of Pahala
Reported by: Official NWS Observations
Coordinates: 20.160, -155.857

Winter Storm, Big Island Summit

When: December 10, 6:15 PM HST to December 11, 3:03 AM HST
Where: Big Island Summit forecast zone
Reported by: COOP Observer
Coordinates: 19.602, -155.523 (the zone’s center; the record gives no point)

Hawaii Institute for Astronomy personnel reported 6 to 8 inches of snow, with some drifts up to 1 foot, on the summit of Mauna Kea.

Heavy Rain, Honolulu

When: December 11, 3:11 AM HST to 5:53 AM HST
Where: Honolulu County, 2.24 mi NW of Makaha Valley to 0.16 mi WSW of Waimalu
Reported by: Official NWS Observations
Coordinates: 21.507, -158.220

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
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.
Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.

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

The same day elsewhere

Every storm in Hawaii in 2010 Every state in 2010 This day in weather history Warnings in Hawaii, December 2010

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: 267451, 267448, 267450, 267459, 267467, 267468, 267472, 267473, 267474, 267476, 267479, 268669, 267490.