Five Category 4+ tropical cyclones have struck U.S. soil in 14 months.

Ian Livingston, a weather forecaster, writes in the Washington Post regarding something that is quite unprecedented. It has been predicted by various climate models that a warming world will result in more intense tropical cyclones, and that is exactly what is happening.

Ian lays it all out …

Category 5 Super Typhoon Yutu, which decimated the Northern Marianas, is the latest in a string of behemoth storms to directly strike U.S. soil since August 2017. The United States or U.S. territories have been hit by five Category 4 or stronger tropical cyclones in the past 14 months. This is probably without precedent.

Brian McNoldy, a tropical-weather researcher at the University of Miami who examined historical data, could not find more than two Category 4 or stronger storms that previously hit the United States over a two-year period.

Category 4 and 5 storms are the most violent class of hurricanes, packing winds of at least 130 mph, and are notorious for their destructive force and, often, high death tolls.

The barrage began with Hurricane Harvey in August 2017. Then came Irma and Maria during the historic September 2017 hurricane outbreak in the Atlantic Ocean. This year, we’ve seen Hurricane Michael and now Super Typhoon Yutu. These storms have all wrought devastation where they’ve struck and will be remembered for generations.

He is not alone in making this observation …

Clarifying Terms and explaining why it is like this

Ian used the term “Tropical Cyclone”, but there are other commonly used phrases that are used to describe exactly the same thing. In the Atlantic or the Northeastern Pacific we call it a Hurricane. When it happens in the Northwestern Pacific then we call it a Typhoon.

These are all rotating storm systems with a low pressure hub in the centre. The energy source that drives this is the evaporation of water over warm bodies of ocean. The water vapour rises, then condenses and falls again. Due to the conservation of angular momentum imparted by the Earth’s rotation the entire mass rotates. Because it is the vast areas of warm ocean that are essentially the fuel that drives these weather engines then whenever one crosses over land it will lose access to the energy source and become weaker.

Why More Intense?

Remember that the primary energy source for these weather systems is warm oceans. If you pump more energy into the oceans and warm them up even further, then the rather obvious and quite measurable result is that you will increase the strength of the Hurricanes that they generate. This is not an opinion, just basic physics. The Hurricane wind speed will increase by roughly eight meters per second for each degree Celsius of warming. As Ian has now pointed out, the strongest storms are getting stronger and that trend will continue as the pace of warming continues.

Additionally, a stronger storm will in turn also lead to a bigger storm surge and so we also end up with even more costal flooding.

Warmer Atmosphere
The warmer the atmosphere is the greater is its ability to transport more moisture and then drop it on us. This also is very basic Physics and is measurable. The Clausius-Clapeyron equation enables us to understand that each degree of Celsius will lead to roughly seven percent more moisture.

Other factors
Beyond the above we also have the observation that there are other factors also in play. For example, the storms are moving a lot more slowly. The current climate models predict exactly this for human caused climate change – an expansion of the sub-tropical region of high-pressure and also a far northward-shifted jet stream.

Climate Impact

Climate Change is having a direct measurable impact. This is not a new insight, but instead has been appreciated for some time now, so much so, that Al Gore and others, who were paying attention to the subject matter experts have been vocally and persistently telling us this.

If you disagree then you will discover that your argument is not with either Al Gore or the subject matter experts, it is with the basic laws of physics. Good luck winning that argument.

The impact from Climate Change is not off in some far and distant future, it is here now.

The Latest Storm – Super Typhoon Yuta

This one just happened and it has been a true monster of a storm – a full Category 5 superstorm with sustained wind speeds of 180 mph, and gusts of wind reaching a mind-blowing 219 mph. This would qualify as a category 6 or even a 7 if we had such a thing, but the scale tops out with category 5.

Yuta Quotes

“We just went through one of the worst storms I’ve seen in all my experience in emergency management,” said a statement from emergency management officials for the commonwealth, known as the CNMI.

The National Weather Service in Guam had warned residents that the winds would be so strong that “most homes will sustain severe damage with potential for complete roof failure and wall collapse. Most industrial buildings will be destroyed.”

Still, Mafnas said, he was “at a loss for words” when he first saw the havoc Yutu wreaked on his island. “I knew the damage would be significant, but coming out in the morning, even with that knowledge, I was still surprised by how devastating it was,” he said.

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