A strong cold front produced heavy rain, thunderstorms, and flash flooding over much of the island chain, and even heavy snow over the summits of Mauna Kea and Mauna Loa on the Big Island of Hawaii. The system also induced strong winds ahead of it.
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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 strong cold front produced heavy rain, thunderstorms, and flash flooding over much of the island chain, and even heavy snow over the summits of Mauna Kea and Mauna Loa on the Big Island of Hawaii. The system also induced strong winds ahead of it. The costs of damages were 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 Jan 12, 3:25 AM HST, 6 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HONOLULU HI 325 AM HST WED JAN 12 2011 .SYNOPSIS... A WET AND WINDY WEATHER PATTERN WILL PREVAIL OVER THE STATE TODAY THROUGH MUCH OF THURSDAY. GUSTY SOUTHERLY WINDS...HEAVY RAIN SHOWERS AND EVEN SOME THUNDERSTORMS ARE EXPECTED AS A COLD FRONT APPROACHES FROM THE WEST. THE COLD FRONT WILL STALL AND WEAKEN OVER THE WESTERN PORTION OF THE STATE THURSDAY. AFTER THE FRONT DISSIPATES...CONDITIONS WILL GRADUALLY BECOME DRIER FRIDAY AND SATURDAY WITH LIGHTER SOUTHERLY WINDS. ANOTHER COLD FRONT IS FORECAST FOR LATE SUNDAY OR EARLY MONDAY. && .DISCUSSION... QUICKLY DETERIORATING WEATHER CONDITIONS EARLY THIS MORNING WILL USHER IN A PERIOD OF ACTIVE AND POTENTIALLY HAZARDOUS WEATHER THROUGH THURSDAY. THERE ARE A VARIETY OF WEATHER CONCERNS FOR THIS MORNING ACROSS THE STATE...HEAVY SHOWERS BRINGING THE POTENTIAL FOR FLASH FLOODING...SCATTERED THUNDERSTORMS WITH THE RISK FOR DAMAGING WINDS...STRONG KONA WINDS DEVELOPING AHEAD OF THE APPROACHING COLD FRONT...AND DANGEROUS WINTER STORM CONDITIONS OVER THE BIG ISLAND SUMMITS. A VERY MOIST AND UNSTABLE AIRMASS IS POSITIONED JUST SOUTH OF THE MAIN HAWAIIAN ISLANDS EARLY THIS MORNING. A LARGE AREA OF HEAVY SHOWERS AND SCATTERED EMBEDDED STRONG THUNDERSTORMS IS MOVING NORTHWARD ALONG THE LEADING EDGE OF THE MOIST AND UNSTABLE PLUME. VERTICAL WIND PROFILES SUGGEST AN ENVIRONMENT FAVORABLE TO PRODUCE STRONG WIND GUSTS OF 40 MPH...AND LOCALLY AS HIGH AS 50 MPH AS THESE HEAVY SHOWERS AND THUNDERSTORMS MOVE ACROSS THE STATE THIS MORNING. IN ADDITION...RAINFALL RATES WILL BE QUITE HIGH...WHICH WILL QUICKLY RAISE THE THREAT OF FLASH FLOODING. HAVE PUT THE FLASH FLOOD WATCH IN EFFECT IMMEDIATELY THIS MORNING TO COVER FOR THE EARLY ARRIVAL OF THE HEAVY SHOWERS. THE THREAT OF FLASH FLOODING WILL REMAIN AN ISSUE TODAY THROUGH THURSDAY AS THE MOIST AND UNSTABLE AIRMASS OVER THE STATE INTERACTS WITH STRONG DYNAMICS ASSOCIATED WITH THE UPPER TROUGH AND SLOWING COLD FRONT. THE SLOW MOVING COLD FRONT WILL STALL OUT OVER THE WESTERN PORTION OF THE STATE AND IS ALSO OF CONCERN AS THIS WILL TEND TO FOCUS HEAVY RAINFALL ACCUMULATIONS WHERE IT STALLS EARLY THURSDAY. LATEST INDICATIONS THAT THE FRONT WILL STALL NEAR KAUAI OR POSSIBLY AS FAR EAST AS OAHU BY THURSDAY MORNING. GUSTY KONA WINDS WILL BE DEVELOPING THIS MORNING AS WELL...THUS HAVE STARTED THE WIND ADVISORY FOR MUCH OF THE STATE FOR GUSTY SOUTHWEST WINDS AND THIS ADVISORY WILL CONTINUE THROUGH EARLY THURSDAY AS WELL. THESE GUSTY WINDS WILL BE ESPECIALLY FELT IN AREAS WHERE THEY DOWNSLOPE ON THE NORTH AND EAST SIDES OF THE MOUNTAIN RANGES...SUCH AS KANEOHE AND WAIALUA...WHERE DATA SUGGESTS GUSTS TO 50 MPH ARE POSSIBLE. WEATHER CONDITIONS ON THE BIG ISLAND SUMMITS OF MAUNA KEA AND MAUNA LOA HAVE ALREADY DETERIORATED THIS MORNING WITH SNOW SHOWERS AND GUSTY WINDS IN PROGRESS. THE WATCH HAS BEEN UPGRADED TO A WINTER STORM WARNING AND CONTINUES IN EFFECT THROUGH THURSDAY. THE POTENTIAL FOR SIGNIFICANT SNOWFALL ACCUMULATIONS GREATER THAN 12 INCHES TODAY THROUGH THROUGH THURSDAY...COMBINED WITH GUSTY WINDS...WILL RESULT IN CONSIDERABLE BLOWING AND DRIFTING SNOW AND NEAR WHITEOUT CONDITIONS. THE COLD FRONT WILL WEAKEN THURSDAY AFTERNOON AND NIGHT AS THE STORM ENERGY QUICKLY LIFTS OFF TO THE NORTHEAST. BY FRIDAY THE SHOWERS AND WINDS WILL DECREASE GOING INTO THE FIRST HALF OF THE WEEKEND. THE NEXT COLD FRONT IS FORECAST TO MOVE THROUGH THE ISLAND CHAIN LATE SUNDAY INTO EARLY MONDAY...BUT APPEARS WEAKER WITH LESS WIND AND RAINFALL EXPECTED. && .MARINE... FOR THE OFFSHORE WATERS NORTH OF 23N...THE SOUTHERLY WINDS REACHING 35 KNOTS AHEAD OF THE APPROACHING COLD FRONT TODAY HAS NECESSITATED THE CONTINUANCE OF THE GALE WARNING. CLOSER TO THE ISLANDS...THE STRONG SOUTH SOUTHWEST WINDS UP TO 30 KNOTS AND/OR COMBINED SEAS AT 10 FEET OR GREATER DUE TO THE NORTHWEST SWELL WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS THROUGH TONIGHT. THE NORTHWEST SWELL CONTINUES WITH NOT MUCH CHANGE THROUGH THIS MORNING. HIGH SURF ADVISORY WILL LIKELY END BY THIS EVENING. A NEW LARGE WEST NORTHWEST SWELL ARRIVING FRIDAY NIGHT MAY PRODUCE SURF HEIGHTS NEAR HIGH SURF WARNING THRESHOLDS ALONG NORTH AND WEST FACING SHORES SATURDAY. ELSEWHERE...THE SOUTHWESTERLY WINDS INCREASING TODAY WILL AGAIN GENERATE ROUGH...SHORT PERIOD SURF ALONG SOUTH AND WEST FACING SHORES TODAY AND THURSDAY. && .HFO WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 6 PM HST THURSDAY FOR ALL HAWAIIAN ISLANDS. WINTER STORM WARNING UNTIL 6 PM HST THURSDAY FOR THE BIG ISLAND SUMMITS. WIND ADVISORY UNTIL 6 AM HST THURSDAY FOR HALEAKALA SUMMIT...BIG ISLAND SUMMITS...AND MOST AREAS OF OTHER ISLANDS EXCEPT WEST AND SOUTH SHORES OF KAUAI OAHU AND MAUI. HIGH SURF ADVISORY UNTIL 6 PM HST WEDNESDAY FOR NORTH AND WEST FACING SHORES OF NIIHAU...KAUAI...OAHU AND MOLOKAI...AND THE NORTH FACING SHORES OF MAUI AND THE WEST FACING SHORES OF THE BIG ISLAND. SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR ALL COASTAL WATERS. && BRENCHLEY
The South Shore radar (PHWA), 57 km away, was scanning. The volume nearest the first event began at 15:07 UTC.
11 heavy rain, 2 flash flood, 1 winter storm. Local standard time, as filed.
Rangers reported heavy snow accumulations of 6-7 inches.
Flooding reported along Nalopaka Place near Aiea in south central Oahu.
Heavy rain caused a debris flow that closed Kamehameha V Highway for a time near Kawela on the island of Molokai.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Hawaii in 2011Every state in 2011This day in weather historyWarnings in Hawaii, January 2011
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: 284722, 274221, 274222, 274224, 274220, 274228, 274238, 274241, 274243, 274249, 274279, 274252, 274254, 274256.