Satellite imagery reveals a storm with a well-defined eye, excellent symmetry and deep convection around its core. Its outer bands are already lashing the coast and the eye should move ashore late today.
AccuWeather’s Jesse Ferrell, reviewing the history of storms to strike Madascar, found that Giovanna’s track most closely remembles cyclone Geralda from 1994. That storm “destroyed 80% of the city’s seaport Toamasina.” IRIN news said Geralda “killed about 200 people, displaced 40,000 and affected another 500,000.”
In addition to the destructive category 4 intensity winds, a large storm surge and 4-8” or more of flooding rain are also likely with this storm.
Wunderground’s Jeff Masters notes an elevated risk of damage relative to past storms due to deforestation over the last 30 years, which will worsen runoff from flood waters.
As Giovanna crosses Madagascar, it will weaken considerably before it re-emerges over the water late Tuesday or early Wednesday. It is then forecast to strike Mozambique as a tropical storm or depression late this week.