Are Tropical Cyclone Rainfall Rates Increasing?

By Paul Homewood


There is no evidence that tropical cyclones are getting more frequent or more intense, but are they getting wetter?

This is a common suggestion, and is something that is predicted by climate models.

One of the problems with measuring past trends is the patchy nature of recorded data. Whereas we now have much more complete data, and an abundance of measuring sites, in the past this was not always the case.

This is a critical issue, because extremes in rainfall are, by nature, usually very localised. If you don’t have a rain gauge at that precise location, you will end up underestimating the amount of rain.


Walsh et al published a very detailed and up to date assessment of the state of tropical cyclone science, “Tropical Cyclones and Climate Science”, in 2015. It had this to say about rainfall:



Walsh et al


In reality, it will be decades before we can start to get meaningful trends, but this will not stop alarmists jumping up and down every time a TC brings bad floods.


As the Miami Herald reminded us last year, Harvey may have been terrible, but it was a long way from being the worst:



Hurricane Harvey might have beget rain in biblical volume and billions in flood damage when it stalled over Houston, but it’s not the wettest storm delivered by the Atlantic.

Not by far.

Cuba got hammered by more than 100 inches of rain when Hurricane Flora sat over the island for four days in 1963. And even earlier, in 1909 before hurricanes were named, a storm dropped more than 96 inches of rain on Jamaica. In more recent history, Wilma dumped more than 62 inches of rain on Mexico in 2005 and Hurricane Mitch, blamed for killing more than 11,000 in Central America in 1998, soaked Nicaragua with more than 62 inches, according to records compiled by National Oceanic and Atmospheric Administration forecaster David Roth.

As Texas digs its way out of what’s likely to be the state’s worst natural disaster in history, the widespread flooding that submerged whole towns and sent 30,000 people to shelters serves as a sobering reminder that hurricanes may be defined by wind. But their most lethal weapon is usually water.


March 23, 2018 at 01:03PM

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