Category 4 Tropical Cyclone Enawo Hits Madagascar

Extremely dangerous Tropical Cyclone Enawo hit northeastern Madagascar near 3 am EST Tuesday as a Category 4 storm with 145 mph winds. Enawo is the third strongest tropical cyclone on record to strike the island, and severe impacts are likely from the storm’s torrential rains, high winds, and large storm surge (though in their 1 am EST (6 UTC) Tuesday advisory, Meteo France in La Reunion reduced their peak storm surge forecast for the storm to 1 - 2 meters.) Of most concern are the rains from Enawo, as it is an unusually large and wet storm. The amount of water vapor detected by satellite is near the very high end of what is observed in tropical cyclones—precipitable water values up to 3.0 inches. Recent runs of the HWRF model (Figure 2) predict extreme rainfall amounts falling on heavily populated regions of Madagascar, and Enawo has the potential to be a top-three most damaging storm in the island’s history. Enawo will decay rapidly as it takes a track directly down the length of Madagascar, exposing the entire island to flooding rains. However, the disaster could have been worse—more than half of the rivers in Madagascar have dried up or are flowing at less than 5 percent of their average streamflow, thanks to a two-year El Niño-linked drought. Enawo’s rains will help break the drought, which has caused large-scale crop failures and put over half a million people into acute food insecurity, according to the Famine Early Warning Systems Network.


Figure 1. Visible MODIS image of Enawo taken at 10:24 UTC (5:24 am EST) Tuesday March 7, 2017. At the time, Enawo had just made landfall over northeast Madagascar as a Category 4 storm with 145 mph winds. Image credit: NASA.


Figure 2. Predicted storm-total rainfall amounts for Tropical Cyclone Enawo from the 06 UTC Tuesday (1 am EST) March 7, 2017 run of the HWRF model. Rainfall amounts in excess of 16 inches (orange colors) are expected in many areas of Madagascar, with 4 - 8” expected near the capital of Antananarivo (population 1.6 million).


Figure 3. Streamflow as a percent of average in Madagascar on March 4, 2017. Most rivers on the island were flowing at less than 5 percent of average due to a two-year El Niño-linked drought. Image credit: Princeton African Flood and Drought Monitor.

Enawo is the strongest tropical cyclone in the Southern Hemisphere so far in the 2016 - 2017 season, and the first one to exceed Category 1 strength. It has been an unusually quiet tropical cyclone season in the Southern Hemisphere this year, as we discussed in detail in a February 28 post.

Madagascar’s cyclone history
According to NOAA’s Historical Hurricane Tracks website, Madagascar has been struck by twelve major (Category 3 or stronger) tropical cyclones since 1983. The deadliest of these was Tropical Cyclone Gafilo, which hit the island on March 7, 2004, as a Category 4 storm with 150 mph winds. Gafilo killed 363 people; damage was estimated at $250 million, the fifth costliest natural disaster on record in Madagascar. The island’s costliest storm was Tropical Storm Emilie, which caused devastating flooding on February 1, 1977 of $1.4 billion (2017 dollars.) The strongest cyclone to hit Madagascar was Cyclone Hary, which brushed the northeastern coast of the island on March 10. 2002, as a Category 5 storm with 160 mph winds. Hary was a small storm, and caused four deaths and relatively little damage in Madagascar.


Figure 4. Tracks of all major (Category 3 and stronger) tropical cyclones to make landfall in Madagascar, 1983 - 2016. Image credit: NOAA’s Historical Hurricane Tracks website.

Jeff Masters