Catastrophic wind pushes palm trees sideways and sends debris flying into the air as Hurricane Michael pounded parts of the Florida Panhandle.
Hurricane Michael was a storm for the record books, and by one important measurement was more powerful at landfall than notorious past monsters such as Katrina or Andrew.
When measured by its barometric pressure of 919 millibars, Michael was the third-strongest hurricane to ever make landfall in the United States, according to Colorado State University meteorologist Phil Klotzbach.
A “millibar” is how meteorologists determine barometric pressure. The lower the millibar number, the stronger the storm.
Michael trails only the 1935 “Labor Day” hurricane (892 millibars) that battered the Florida Keys and Hurricane Camille (900 millibars), which slammed into the Gulf Coast in the summer of 1969.
Instead of wind speed, barometric pressure should be considered the best way to measure a hurricane’s strength, Derrick Herndon, an atmospheric scientist at Cooperative Institute for Meteorological Satellite Studies, told National Geographic.
And referring to a hurricane’s damage, a study last year in Nature Communications said that “pressure better explains historical economic damages than does maximum wind speed.” This is because central pressure combines both wind speed and storm size, the study said.
At landfall, Hurricane Katrina was measured at 920 millibars. But because eventually Katrina flooded a big city like New Orleans, killing over 1,000 people, it will certainly always be considered a more devastating and destructive storm than Michael, which primarily hit a lightly populated area.
When measured by sustained wind speed at landfall – which was 155 mph near Mexico Beach, Florida – Michael drops to fourth place behind those two hurricanes and also 1992’s Hurricane Andrew, Klotzbach said.
The 1935 hurricane hit with winds of 184 mph, Camille’s winds were 173 mph, and Andrew roared ashore into south Florida with winds of 166 mph.
The well-known, 47-year-old Saffir-Simpson scale of hurricane intensity – with its familiar Categories from 1 to 5 – only measures wind speed. Those three hurricanes (Labor Day 1935, Camille and Andrew) remain the only Category 5 hurricanes to hit the United States.
A Category 5 hurricane has winds of at least 157 mph. Michael missed joining that infamous level by only 2 mph.
However, whether measured by wind speed or barometric pressure, both of those readings may still miss the mark of a hurricane’s impact.
For example, while Michael’s Category 4 rating accurately conveyed its destructive power, Hurricane Florence’s Category 1 landfall last month was an example of the scale’s limitations. The scale does not take heavy rain – and the resulting inland flooding – into account.
Water, whether storm surge from the ocean or flooding from heavy rain, often ends up being much more deadly and destructive than the wind of a hurricane.
Florence killed dozens of people and caused tens of billions of dollars of damage in the Carolinas in September.
Contributing: The Associated Press
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