A new rainfall world record

The world record for most precipitation in a 72-hour period was shattered this month when the French island of La R�union recorded 12.9 feet (3.929 meters) of rain. La R�union is a small island in the South Indian Ocean east of Madagascar. Despite the island's small size--about 30 miles across--it has two tall volcanoes that rise over 8,500 feet in altitude. These volcanoes can squeeze prodigious amounts of rain out of the moist tropical atmosphere when strong winds force this moist air up their flanks. La R�union already held the world record for a 3-day precipitation event, the 3.24 meters that fell during January 1980 in Tropical Cyclone Hyacinthe. Another tropical cyclone--Category 3 Tropical Cyclone Gamede--set the world record this time. Gamede never hit the island, but passed close enough (120 miles away) and moved slowly enough that its outer spiral bands stayed over the island for many days. The 3-day record was set at Commerson's Crater, a remote site at 7,500 feet altitude. The village of Hell Bourg at 3000 feet altitude also exceeded the former world record, measuring 3.264 meters of rain over the same 3-day period. Regions along the island's shore received much less rain--Gillot, 0.439 meters, St-Beno�t, 0.309 meters, and Pierrefonds, 0.247 meters.

Gamede's rains also brought world records for the most rain recorded for multi-day periods up to nine days:

3 days: 12.9 feet (3.93 meters)
4 days: 16.0 feet (4.87 meters)
5 days: 16.3 feet (4.98 meters)
6 days: 16.6 feet (5.07 meters)
7 days: 17.7 feet (5.40 meters)
8 days: 18.1 feet (5.51 meters)
9 days: 18.1 feet (5.51 meters)

The 10-day record was not broken, and is still held by Tropical Cyclone Hyacinthe's 18.4 feet of rain that fell from January 18-27, 1980.


Figure 1. Tropical Cyclone Gamede on February 27, 2007 at 10am local time, as it brought world-record rains to La Reunion Island in the Indian Ocean. At the time, Gamede was a Category 2 storm with top winds of 100 mph. Image credit: NASA Earth Observatory.

I'll be back Wednesday or Thursday with a new blog.

Jeff Masters