A Major Rainfall Event: The 27 February–5 March 1993 Rains on the Southeastern Slope of Piton de la Fournaise Massif (Reunion Island, Southwest Indian Ocean)

Abstract

Exceptionally heavy rainfall affected the whole of Reunion Island from 27 February to 5 March 1993. The period was characterized by the persistent incursion of monsoonal northwesterlies down to the latitude of Reunion and by the presence of a powerful, stationary anticyclone south of the Mascarenes. The contact of these air masses formed an area of active convergence in which a weak, short-lived tropical depression developed. This instability in the southeasterly airstream generated particularly heavy rains on the steep eastern slopes of the Piton de la Fournaise massif through a classic orographic mechanism. A meteorological station located on the southeast windward slope of the Piton de la Fournaise massif at an altitude of 1600 m collected world record rainfall totals during this event. The rain was of “moderate” short-term intensity (0.5–4.5 mm min−1) but persisted for many days, exceeding local records on 2- to 8-h intervals and world records on 2- to 7-day intervals. A comparison with heavy rainfall events in 1994 and 1995, and a study of daily rainfall totals show the event was not unprecedented for Reunion Island and that the record-breaking rainfall totals were due, at least in part, to monitoring rainfall at a newly opened high-elevation location.