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Author Topic: Atlantic hurricane rapid intensification trends  (Read 216 times)

Offline EricPeterson

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Atlantic hurricane rapid intensification trends
« on: November 24, 2020, 1817 UTC »
Continuing my exploration of the HURDAT2 dataset, I've calculated trends for the rapid intensification of hurricanes in the Atlantic basin. The claim is that warmer waters from global warming are leading to more episodes of RI.  I believe that claim is true for some categories of RI although there is a lot of natural variation.  However the vanilla claim of RI, which is defined as strengthening of 30 knots or more in 24 hours, is very common, about 60% of all hurricanes have at least one 24 hour period with >= 30 knots of strengthening.  That 60% number is flat over the past 30 years:


However if you consider all tropical storms, not just hurricanes, there's a pronounced drop in RI:


I believe that is due to the detection and naming of more tropical storms.  There's an insinuation in some news stories that the glut of named storms this year is also due to global warming.  But they have to pick one thing to blame on global warming: more rapid intensification or more named storms, and then show the evidence.  I believe that Wilma (2005) and Felix (2007) are potential evidence of extreme RI that might be increasing although it is very sporadic.
Finally I also calculated and plotted rapid weakening. 

Not surprisingly a number of the strongest storms weakened rapidly.  I explicitly excluded weakening over land since that is obvious and not what I am looking for.  I assume the trend in rapid weakening should be flat.  Storms that head into high latitudes can weaken rapidly but there should be no trend in high latitude movement over time.  Instead I see a slight uptick in rapid weakening over time.  The descriptions of those storms sometimes include the phase "unexpected collapse".
Graphs and link to code at https://virtualcoinclub.com/wx/ri/  The page includes a table generated from the data of all the rapidly intensifying storms since 1950.