First Marco, then Laura. This week the Caribbean and US Gulf coast have been battered by two tropical storms that arrived just a couple of days apart.
Mid-August to mid-September is peak Atlantic hurricane season, but having two storms in such close succession is unusual and demonstrates just how active this season has been.
When one storm follows another, the second storm is often weaker than it might otherwise have been. That’s because the ocean churn created by the first tropical cyclone cools the surface waters, lessening the heat available to feed and fuel the second.
Previous research, published in Geophysical Research Letters, showed the cooling influence of a tropical storm could last for more than 30 days, suggesting between one in 10 and one in three tropical cyclones is dampened down by the storm that preceded it.
Karthik Balaguru, from the Pacific Northwest National Laboratory, and colleagues calculate this process reduces the mean intensity of tropical cyclones by 3-6% during average years, and by up to 15% during active years such as this one.
But in this case, it appears that Laura has veered off on her own course and gathered strength, neatly avoiding any potential damping influence from Storm Marco.
