NASA observes the formation of Tropical Storm Aletta

Friday, 08 Jun, 2018

"Hurricane Harvey a year ago was a great example of what a slow storm can do". The fact that their results show quite similar trends should be a wake-up call.

Scientists expect climate change is going to make tropical cyclones - including hurricanes - more severe.

Although more rainfall is the most direct effect of slower-moving storms, other impacts can be enhanced as well.

"We've kind of hypothesized that this type of behavior may happen, this slowing down of the forward speed of the cyclones", said Colin Zarzycki, a climate scientist at the National Center for Atmospheric Research who has reviewed at Kossin's study.

The western North Pacific basin, where the strongest systems are referred to as typhoons and super typhoons, sees the most storms annually and has seen the most slowing, at 20%.

Gutmann and Kossin took entirely different approaches-one looking at historical data; the other using modeling to see how storms would behave under predicted warming scenarios.

The Atlantic Basin remains inactive and the storm now has a zero threat to life or land.

"Still, it's entirely plausible that local rainfall increases could actually be dominated by this slowdown rather than the expected rain-rate increases due to global warming".

"The storms will stay in your neighbourhoods longer", he said. "I'm finding something that might be considered consistent [with climate change], but, really, no idea what's contributing what to this signal". Indeed, after around 1980, we could observe them by geostationary satellite - before that, storms in the open ocean might have been missed completely and gone unrecorded, at least if they never encountered any vessel.

In a warming world where atmospheric circulations are expected to change, the atmospheric circulation that drives tropical cyclone movement is expected to weaken.

While the new research suggests hurricanes and typhoons are slowing down over time, more work needs to be done to improve prediction models for how hurricanes may behave in the future.

The reduced speed leads to heavier rainfall and an increased risk of flooding. Follow him on Facebook, Twitter and Instagram.