Poster GCANE at Storm2K posts the graphic below from NASA and explains:
Also at NASA Goddard, a 3-D image of Hurricane Maria was made to understand what was happening within the storm. The dual-frequency radar on the Global Precipitation Measurement (GPM) satellite saw an impressively tall thunderstorms cell of precipitation in the compact eyewall of Hurricane Maria on Monday, Sept.18, 2017. "Enough water vapor was condensing into rain inside of this cell that rapid updrafts developed, rapid enough to lift the precipitation until it froze and then even higher until it penetrated into the lower stratosphere at 16.75 km altitude," said Owen Kelley of NASA Goddard's Precipitation Processing System..
"This tall cell (also known as a "hot tower") was part of a sequence of such cells that were seen by infrared satellite instruments, such as the one on the recently launched GOES-16 satellite. Meanwhile, Maria put on an unexpectedly fast intensification from category 1 to category 3 on the Saffir-Simpson scale on Monday (Sept. 18)."
Research conducted at NASA, at the University of Maryland, Baltimore County, and elsewhere suggests that a sequence of hot towers, also known as a "convective burst," is one a way to detect that a hurricane's heat engine going into high gear. The end result is intensified winds circling the eye at the ocean's surface.
Maria continued to intensify after GPM passed overhead and reached Category 5 status that night.
