The stagnation of tropical storm Debby brought days of heavy rain and flooding – a climate scientist explains what happened

Tropical Storm Debby was move so slowlyThe Olympic athletes could have escaped it when it moved across the Southeast in early August 2024. This gave the rain time to flood towns and farms in large parts of Florida, Georgia and the Carolinas. More than a foot of rain had fallen in some areas by early August 7, 2024, with more rainy days There and within the northeast there’s a risk of flooding.

Matthew Barlowa climate scientist at UMass Lowell, explains how storms like Debby pick up a lot moisture, what could cause them to slow or stop, and what climate change has to do with it.

What causes hurricanes to stop?

Hurricanes are controlled by the weather systems they interact with, including other storms moving across the United States and the Bermuda High over the Atlantic.

A hurricane may crawl because there are not any weather systems close enough to drag the hurricane along, or because there’s a high pressure system north of the hurricane that blocks its forward movement.

In this case High pressure area over the western USA slowed Debby's progress, and the Bermuda High – a big, clockwise wind circulation that normally moves up the East Coast – was not close enough to matter.

Something similar happened with the remnants of Hurricane Harvey in 2017, one in every of the best-known examples of a stalled hurricane. High pressure over the USA blocked his forward movement and made him fall greater than 50 inches of rain in parts of Texas.

Slower-moving storms have more time to dump rain over the identical area, which may dramatically increase the chance of flooding, because the Southeast is currently experiencing with Debby.

How can Debby carry a lot rain?

The surface temperatures of the Atlantic Ocean and the Gulf of Mexico were much warmer than average for the past 12 months. At the moment there’s a very wide area with exceptionally warm There, sea surface temperatures are very high, which suggests strong evaporation.

In addition, the air is warmer than average and warm air can hold far more moisture.

So more evaporation from a hotter ocean pumps more moisture into warmer air, which may hold more. This “more and more” has led to a whole lot of moisture within the air over this massive area, from the Gulf of Mexico to the East Coast, and that's the realm Debby is moving through. The storm is pulling in a unprecedented amount of moisture from all directions – it's the right environment for very heavy rainfall.

The warm, moist air can also be spreading to the East Coast, so heavy rains and flooding are forecast for the Mid-Atlantic region and possibly the Northeast because the storm moves north and interacts with other weather systems.

Debby can also be move near the coast. Because there’s more water within the air over the ocean, the storm can last more since it has a reservoir of fuel. Had Debby moved further inland, the storm would have died down more quickly.

What impact does climate change have on tropical cyclones?

Human-induced climate change is Warming of the ocean and atmosphere. This warming is essentially resulting from the Combustion of fossil fuelswhich Emit greenhouse gases that trap heat near the Earth’s surface.

The combination of warmer ocean and warmer atmosphere can lead to higher rainfall amounts and more rapidly intensifying storms.

There can also be evidence that hurricanes within the USA Slowing down their forward movement and that this may increasingly be related to climate change, but this connection is just not yet sufficiently understood.

Without a rapid reduction in fossil fuel emissions, these storms and their rainfall will proceed to extend. The excellent news is that humanity knows methods to reduce emissionsand there are initial efforts to maneuver the world on this direction.

What does Debby have in store for the Northeast?

Tropical Storm Debby is predicted will proceed to maneuver slowly over the southern United States or simply off the coast for several days, with a high risk of excessive rainfall and parts of the Carolinas specifically are vulnerable to catastrophic flooding.

Significant rainfall can also be expected in parts of the Mid-Atlantic and the Northeast. The area from Philadelphia to New York City is already under flood warnings ahead of the storm, partly resulting from a frontal boundary where tropical moisture can accumulate.

Once Debby moves through and interacts with other systems, its motion is forecast to speed up and move toward Atlantic Canada, leaving massive flood damage in its wake.