Hurricanes Around The World Took A Strange, Long Pause In October/November

This map looks like spaghetti thrown against a wall, but it
a map of all the Atlantic tropical storms and hurricanes 
this year. It was the 6th busy season in a row.

 For some reason, the world temporarily stopped seeing hurricanes for more than a month.  That, my friends, is rather strange. 

As the Washington Post's Capital Weather Gang reported last week:

"It's not just the Atlantic that's been eerily quiet. All across the world, the tropics have been devoid of significant cyclone activity. Not a single hurricane-strength storm has formed anywhere on the planet since October 29, a calm occupying the Northern and Southern hemispheres. That's happened only twice before since 1966, according to Phil Klotzbach, a hurricane researcher at Colorado State University."

The other two years were 1973 and 2012.

The tropical weather drought finally ended a couple days ago with the formation of a typhoon in the western Pacific Ocean.  This typhoon is expected to pass east of the Philippines this week, then dissipate.  

Whether they're called hurricanes, typhoons, cyclones or whatever, they are all the same thing. A strong storm, born in the tropics, with a warm core, no warm or cold fronts and lots of destructive potential with top sustained winds of 74 mph or greater. 

Maybe even more strangely, there has not been a strong hurricane in the world since September 25. A strong hurricane, or cyclone, or typhoon, whatever you want to call it, is a Category 3 on a scale of one to five, with top winds of at least 111 mph.

Up until early October, the Atlantic Ocean hurricanes season was a messy and destructive powerhouse. It was one of the busiest seasons on record. It was also, remarkably, the sixth consecutive Atlantic hurricane season with well above normal activity.

The list of potential hurricane names was exhausted. Tropical storm Wanda did manage to form in the Atlantic in early November, and Wanda was the last name on the list. Its winds stayed under 74 mph, so it the world's hurricane-free streak contineud.  Wanda, by the way, was the first known tropical storm to form from what had been a destructive New England nor'easter, as Jeff Masters notes in Yale Climate Connections.

While we're talking about New England, Masters has this bit of weird 2021 tropical storm trivia. 

Back around August 11, a strong non tropical storm system caused a line of severe, destructive thunderstorms in Michigan and the Mid-Atlantic States, causing an estimated $1.1 billion in damage. The storm moved off the coast, turned into a tropical storm and then eventually made landfall as a tropical storm in Westerly, Rhode Island. This whole scenario was a first, too! 

The Atlantic tropical season officially ended on Tuesday.  However, there is a very low, but not zero chance of tropical development in the Atlantic during December. It's happened before.   This year, the Atlantic, after being super busy, just gave up the ghost in October.

Generally speaking, when the Atlantic hurricane season is busy, the northern half of the Pacific Ocean tends to be quiet, 

As the Washington Post explains it, we're in an La Nina pattern, which favors cool waters in the eastern Pacific Ocean. That helps create lighter upper level winds in the Atlantic Ocean. If upper level winds are lighter, nascent tropical storms have a better chance of forming. So it's no surprise most of the Atlantic season was busy this year. 

And also not a big surprise that the western Pacific Ocean was relatively quiet in 2021. 

At the same time La Nina tends to increase upper level winds in the Pacific, which helps explain why hurricanes and typhoons were relatively hard to come by there. 

The mystery is why the Atlantic hurricane season mercifully collapsed in October. Often, the Caribbean Sea gives birth to tropical systems in October and November, but this year it did not. Perhaps there was too much sinking air that prevented thunderstorms from developing. Tropical storms there can develop from these clusters of storms.  

I wouldn't make too much of this collapse in tropical storm activity, which seems to be ending now. There doesn't seem to be any good conclusions as to whether climate change will increase the global supply of hurricanes. 

Climate change is probably making some of them stronger, or making some tropical storms form in weird places or weird times.  But the world will always have busy hurricane episodes, and quiet ones, too. Raise a glass to the quiet times, right?