The largest rainfall from a tropical system in the U.S. was recorded during Hurricane Harvey back in 2017. A little more than 60” of rain fell from August 25-29 in Nederland, Texas, a suburb of Houston.
Harvey made landfall as a category 4 hurricane but for most of its lifetime over the Lone Star state it was a tropical storm.
How can we pick up so much rain from a tropical storm? It’s all about the forward speed of the system, not the intensity of the system.
A slow-moving tropical storm will almost always produce more rainfall than a fast-moving major hurricane…even a category 5 hurricane. The slower the forward speed the longer a particular area will see heavy rain.
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In the case of Harvey, it downgraded to a tropical storm quickly but sat over the state for over four days! Multiple days of tropical rains will always spell trouble.
We are seeing something similar with Debby. Monday morning it became a tropical storm but it’s expected to drop much more rain from Georgia and points north than it did when it was over Florida as a hurricane.
I bet you can guess why?
Hurricane Season
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Yes, its forward speed is expected to slow down dramatically. We will see widespread rainfall amounts of over a foot and some spots in the Carolinas may see 20"-30” of rain.
Debby will likely go down as a prolific rainmaker.
