Former Hurricane Debbie stalls, causing heavy rains and floods on East Coast

Tropical Storm Debby It’s moving very slowlyA tropical storm moving across the Southeast in early August 2024 could have caught up with the Olympians, bringing rains that would have flooded cities and farms across a wide swath of Florida, Georgia and the Carolinas. 1 Foot of Rain By the early morning of August 7, 2024, precipitation had decreased in some areas, More rainy days It’s forecast there and in the Northeast.

Matthew BarlowClimate scientist David Schneider of the University of Massachusetts Lowell explains how storms like Debby pick up so much moisture, what causes them to slow down or stall, and what climate change has to do with it.

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What causes a hurricane to stall?

Hurricanes are directed by interacting weather systems, such as other storms moving across the United States or the Bermuda High in the Atlantic Ocean.

A hurricane may move slowly because there is no weather system close enough to pull it along, or because there is a high pressure system to the north of the hurricane that is blocking its progress.

In this case, high pressure over the western US was slowing Debby’s progress, and the Bermuda High (a large clockwise wind circulation that normally moves north up the East Coast) was not close enough to have any effect.

This is similar to what happened to the remains of 2017’s Hurricane Harvey, one of the best-known examples of a stalled hurricane: High pressure over the U.S. blocked Harvey’s progress, dumping more than 50 inches of rain on parts of Texas.

Slow-moving storms can dump rain over the same area for a long period of time, dramatically increasing the risk of flooding, as the southeast is experiencing with Debbie.

How is Debbie carrying so much rain?

Surface temperatures in the Atlantic Ocean and Gulf of Mexico have been significantly warmer than average over the past year. A very large area is currently experiencing abnormally warm sea surface temperatures, which is causing high evaporation.

The air is also warmer than average, and warmer air can hold more moisture.

So when you have more evaporation from the warming oceans, it pumps more moisture into the warming air, and the air can hold more moisture. So what happens is this increase, this increase, brings a lot of moisture into the air over this wide area from the Gulf of Mexico up the East Coast, which is where Debby is moving through. This storm is pulling very high moisture from all directions, which is the perfect environment for very heavy rain.

This warm, moist air is also expected to spread along the East Coast, causing heavy rainfall and flooding in the Mid-Atlantic and possibly the Northeast as the storm moves north and interacts with other weather systems.

Debby is also moving closer to the coast. There’s more water in the air over the ocean, which means more fuel reserves and the storm could last longer and be stronger. If Debby had been stronger and moved further inland, the storm would have dissipated sooner.

How is climate change affecting tropical cyclones?

Human-induced climate change is warming the oceans and atmosphere, caused primarily by the burning of fossil fuels, which emit greenhouse gases that trap heat near the Earth’s surface.

The combination of warmer oceans and a warmer atmosphere can lead to increased rainfall and storms intensifying more quickly.

There is also evidence that hurricanes hitting the United States are moving slower, which may be linked to climate change, although the link is not yet fully understood.

Unless we rapidly reduce fossil fuel emissions, these storms and the precipitation they produce will continue to get more intense. The good news is that humanity knows how to reduce emissions, and efforts are underway to move the world in that direction.

What does Debbie expect to bring to the North East?

Tropical Storm Debby is forecast to continue moving slowly over or off the coast of the southern United States over the next few days, putting parts of the Carolinas at high risk for excessive rainfall and devastating flooding.

Parts of the Mid-Atlantic and Northeast are also expected to get significant rain, and flood warnings have already been issued ahead of the storm from Philadelphia to New York City, where a front bringing tropical moisture is expected to bring heavy rainfall.

As Debbie passes through and interacts with other systems, it is predicted to speed up and head toward Atlantic Canada, leaving flood damage over large areas in its wake.

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