Extreme Weather: World-Record Rainfalls During Tropical Cyclone Gamede

Abstract

The World Meteorological Organization (WMO) Commission for Climatology (CCl) evaluation process is applied to two extreme rainfall records occurring at Cratère Commerson on La Réunion Island during the passage of the major Tropical Cyclone (TC) Gamede for inclusion into the WMO CCl World Weather and Climate Extremes Archive. In February 2007, TC Gamede made two approaches to La Réunion Island as it traversed a rather complex path in the Indian Ocean. Gamede's main feature was massive rainfall accumulation inland, with several 3- and 4-day rainfall totals exceeding 2 m. Specifically, an extreme rainfall rate of 3,929 mm over 72 h was recorded at Cratère Commerson, well above the previous world record of 3,240 mm that had been measured at Grand-Ilet during TC Hyacinthe in 1980. In addition, the Cratère Commerson rain gauge registered a rainfall total of 4,869 mm over 4 days; also well above the previous world record. The evaluation committee found that consistent regional rainfall measurements, reliable calibrated equipment, and correct recording procedures were followed throughout the event. Problems with potential wind-induced measurement errors were discussed, but the committee consensus is that such errors tend to underestimate rather than overestimate rainfall accumulations. As shown by analysis of this event, the validation process for the WMO CCl Weather and Climate Extremes Archive provides essential documentation and certification for weather extremes across the world.