Heavy Rain, Kauai
- When
- February 20, 7:01 PM HST to 8:15 PM HST
- Where
- Kauai County, 1.01 mi ESE of Mana to 0.73 mi SSE of Kilauea
- Reported by
- Official NWS Observations
- Coordinates
- 22.063, -159.756
Flash Flood and Heavy Rain in Hawaii, February 20 to 24, 2011
An upper trough triggered heavy rain and thunderstorms over much of the Aloha State. There were no reports of significant injuries.
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
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 triggered heavy rain and thunderstorms over much of the Aloha State. There were no reports of significant injuries. The costs of any 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 Feb 20, 4:00 PM HST, 3 hours 1 minute earlier.
Area forecast discussion, Feb 20, 4:00 PM HST, 3 hours 1 minute before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 400 PM HST SUN FEB 20 2011 .SYNOPSIS... A TROUGH ALOFT WILL DISRUPT THE TRADE WINDS AND PRODUCE UNSETTLED WEATHER THROUGH THE WEEK. && .DISCUSSION... UNSETTLED WEATHER IS LIKELY TO CONTINUE FOR SEVERAL DAYS. THE WEATHER PATTERN OVER THE CENTRAL PACIFIC IS COMPLEX AND THE GLOBAL MODELS ARE INCONSISTENT. FORECAST CONFIDENCE WILL REMAIN LOW UNLESS THE MODELS COME INTO BETTER AGREEMENT. THE REMNANT OF A FRONT EXTENDS NORTHEAST TO SOUTHWEST NEAR KAUAI. A SURFACE RIDGE EXTENDS FROM A HIGH FAR NORTHEAST OF THE ISLANDS TO ABOUT 100 MILES NORTHEAST OF MAUI. THE WINDS NEAR THE ISLANDS ARE BLOWING AROUND THE BOTTOM OF THE RIDGE...FROM THE SOUTHEAST NEAR THE BIG ISLAND...AND FROM THE SOUTH NEAR KAUAI. THERE ARE HEAVY SHOWERS AND ISOLATED THUNDERSTORMS AROUND KAUAI DUE TO CONVERGENCE IN THE SOUTHERLY FLOW...ABUNDANT MOISTURE FROM THE FRONTAL REMNANT...AND INSTABILITY DUE TO A TROUGH ALOFT. WATER VAPOR IMAGERY AND UPPER AIR ANALYSES SHOWS A LOW ALOFT 950 MILES NORTHWEST OF KAUAI WITH A TROUGH EXTENDING SOUTH SOUTHWEST FROM THE LOW. SOUTHWEST WINDS ASSOCIATED WITH THE TROUGH ARE CARRYING HIGH CLOUDS OVER THE ISLANDS. THESE CLOUDS ARE RATHER THICK OVER KAUAI BUT ARE MUCH THINNER OVER THE OTHER ISLANDS. THE MODELS ARE IN PRETTY GOOD AGREEMENT SHOWING THE LOW ALOFT MOVING RAPIDLY OFF TO THE NORTHEAST WHILE THE TROUGH ALOFT CONTINUES MOVING SOUTHEAST TOWARD THE ISLANDS. THE TROUGH ALOFT HAS INDUCED A SURFACE TROUGH WEST OF KAUAI. THE FRONTAL REMNANT NEAR KAUAI WILL MOVE OFF TO THE NORTHWEST TONIGHT...BUT A NEW BAND OF SHOWERS IS FORMING WEST OF THE ISLANDS ASSOCIATED WITH THE SURFACE TROUGH. THE MODELS AGREE IN MOVING THE TROUGH EAST TOWARD THE ISLANDS. THE ASSOCIATED SHOWER BAND WILL MOVE OVER KAUAI MONDAY AND OVER OAHU MONDAY NIGHT. THE TROUGH WILL MOVE EAST QUITE SLOWLY AFTER IT REACHES THE MAIN HAWAIIAN ISLANDS AND WILL CONTINUE TO DISRUPT THE TRADE WINDS AND PRODUCE UNSETTLED WEATHER MUCH OF THE WEEK. THE ATMOSPHERE WILL BE QUITE MOIST AND UNSTABLE...SO PERIODS OF HEAVY RAIN AND ISOLATED THUNDERSTORMS MAY CONTINUE. && .HFO WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY FOR WATERS AROUND THE BIG ISLAND. FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NIIHAU KAUAI AND OAHU. DONALDSON
The radar
The South Kauai radar (PHKI), 28 km away, was scanning. The volume nearest the first event began at 04:59 UTC.
Event by event
8 heavy rain, 1 flash flood. Local standard time, as filed.
Heavy Rain, Maui
- When
- February 21, 11:42 PM HST to February 22, 1:11 AM HST
- Where
- Maui County, 0.28 mi E of Kipahulu to 0.74 mi W of Hana
- Reported by
- Official NWS Observations
- Coordinates
- 20.650, -156.066
Heavy Rain, Honolulu
- When
- February 22, 2:49 PM HST to 4:41 PM HST
- Where
- Honolulu County, 2.31 mi SE of Maili to 0.52 mi ENE of Mililani Town
- Reported by
- Official NWS Observations
- Coordinates
- 21.403, -158.159
Heavy Rain, Honolulu
- When
- February 23, 1:00 PM HST to 2:30 PM HST
- Where
- Honolulu County, 1.63 mi W of Kahuku to 0.87 mi W of Mililani Town
- Reported by
- Official NWS Observations
- Coordinates
- 21.683, -157.975
Heavy Rain, Maui
- When
- February 23, 4:20 PM HST to 6:25 PM HST
- Where
- Maui County, 1.08 mi SSE of Halawa Valley to 3.26 mi NNW of Kamalo
- Reported by
- Official NWS Observations
- Coordinates
- 21.157, -156.741
Heavy Rain, Maui
- When
- February 23, 5:08 PM HST to 11:07 PM HST
- Where
- Maui County, 1.65 mi NW of Pukalani to 1.5 mi SW of Hana
- Reported by
- Official NWS Observations
- Coordinates
- 20.849, -156.366
Flash Flood, Honolulu
- When
- February 23, 5:40 PM HST to 6:42 PM HST
- Where
- Honolulu County, 1.93 mi SSW of Kaneohe Station to 1.95 mi SSW of Kaneohe Station
- Cause
- Heavy Rain
- Reported by
- County Official
- Coordinates
- 21.425, -157.764
Heavy rain caused flooding along Malae Place just off Kaneohe Bay Drive on the windward side of Oahu.
Heavy Rain, Kauai
- When
- February 23, 11:23 PM HST to February 24, 3:06 AM HST
- Where
- Kauai County, 0.84 mi NE of Kokee State Park to 2.17 mi NNW of Anahola
- Reported by
- Official NWS Observations
- Coordinates
- 22.140, -159.662
Heavy Rain, Hawaii
- When
- February 24, 6:11 AM HST to 9:09 AM HST
- Where
- Hawaii County, 4.23 mi NNE of Waikoloa Village to 2.01 mi ESE of Waikoloa Beach Resort
- Reported by
- Official NWS Observations
- Coordinates
- 19.989, -155.764
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
- Cold in Illinois, February 20 to 21, 2011
- Ice Storm and Heavy Snow in Michigan, February 20 to 21, 2011
- Winter Storm in Ohio, February 20 to 22, 2011
- Winter Storm in Pennsylvania, February 20 to 21, 2011
- Winter Storm and Winter Weather in Iowa, February 20 to 21, 2011
- Ice Storm and Lightning Strike in Iowa, February 20, 2011
- Heavy Snow in New York, February 20 to 21, 2011
- Winter Storm in Minnesota, February 20 to 21, 2011
- Blizzard in South Dakota, February 20, 2011
- Ice Storm and Winter Storm in South Dakota, February 20 to 21, 2011
- Winter Storm in Michigan, February 20 to 21, 2011
- Heavy Snow and Winter Weather in Pennsylvania, February 20 to 21, 2011
More
Every storm in Hawaii in 2011Every state in 2011This day in weather historyWarnings in Hawaii, February 2011
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: 277091, 277093, 277094, 277095, 277096, 277097, 277098, 277099, 277100.