Matthew 2016 RI 2

Hurricane Matthew explosively intensifying on September 30, from a category 3 to 5 hurricane.

Rapid deepening, also called rapid intensification, is when tropical cyclones intensify very quickly in a fairly short amount of time. The NHC defines rapid intensification as a 30-kt increase in winds during a 24-hour period, or a 40-mbar drop in pressure during a 24-hour period. Rapid intensification usually requires SSTs of at least 28-29 degrees Celsius, along with low wind shear and a moist environment. An upper-level anticyclone often aids with rapid intensification as well.

Explosive intensification is the more extreme form of rapid intensification. Typically, in explosive intensification, a category 1 hurricane strengthens to a category 5 in 24 hours or less. Examples of storms that have underwent explosive intensification include Hurricane Patricia and Hurricane Wilma.

In the Atlantic, rapid intensification most commonly occurs in the Caribbean Sea, Gulf of Mexico or Western Atlantic Ocean near the Bahamas, where sea surface temperatures are highest. In less common cases, it can also occur in the Tropical Atlantic, such as with Hurricane Danny in 2015 and Hurricane Ike in 2008. In the East Pacific, rapid intensification typically occurs in the eastern part of the basin. Rapid intensification in the Western Pacific is common and can occur throughout the year.