Extreme Weather News

Tropical Cyclone Donna's Extreme Rainfall Evaluated With IMERG

On May 10, 2017 rapidly dissipating tropical Cyclone Donna moved to the southeast of New Caledonia in the South Pacific. In addition to being the most powerful out-of-season tropical cyclone ever recorded in the southern hemisphere, Donna also dropped extreme amounts of rainfall along it's path. Donna spread heavy rainfall along it's path from northern Vanuatu through the Loyalty Islands east of New Caledonia. Over 250mm (~10 inches) of rainfall was reported in the islands of northern Vanuatu as Donna was moving through on May 5, 2017. 

Tropical Cyclone Donna's Extreme Rainfall Evaluated With IMERG

This rainfall analysis was constructed using data from NASA's Integrated Multi-satelliE Retrievals for GPM (IMERG). Data collected in near-real time were utilized in IMERG's rainfall accumulation estimates for tropical cyclone Donna. This analysis covers tropical cyclone Donna for the period from May 2 through early May 10, 2017. IMERG shows that tropical cyclone Donna produced some extremely high rainfall totals. It indicates that the most extreme rainfall accumulation estimates (purple) were greater than 624mm (24.6 inches) . These extreme values were located along Donna's path through the northern islands of Vanuatu. The tropical cyclone passed to the east of New Caledonia on the southern portion of it's track so the Loyalty Islands east of New Caledonia received the heaviest rainfall in that area.

The Integrated Multi-satelliE Retrievals for GPM (IMERG) is a unified U.S. algorithm that provides a multi-satellite precipitation product. IMERG is run twice in near-real time with the “Early” multi-satellite product being created at about 4 hours after observation time and a “Late” multi-satellite product is provided at about 12 hours after observation time. IMERG rainfall totals have been adjusted to reflect observed values in other similar extreme rainfall events.

  • Images and caption by Hal Pierce (SSAI/NASA GSFC)