LSU-Led Team Researches the Impacts of Stalling Tropical Cyclones on the Gulf Coast and Atlantic Coastal Communities

October 14, 2024

Figure 3 is a photo showing the track history for stalling tropical cyclones with colors based on wind intensity according to the Saffir-Simpson Scale and coded at each hourly segment.

Figure 3: Stalling Tropical Cyclone Tracks. The track history for stalling tropical cyclones with colors based on wind intensity (kts) according to the Saffir-Simpson Scale and coded at each hourly segment (1900-2020).

Photo Credit: AMS Journal of Applied Meteorology and Climatology

BATON ROUGE – Jill Trepanier, PhD, professor and chair of the Department of Geography & Anthropology in the LSU College of Humanities & Social Sciences, recently authored an article about stalling North Atlantic tropical cyclones in the Journal of Applied Meteorology and Climatology. The work is a product of a joint effort between LSU and Texas A&M.

The article titled, “Stalling North Atlantic Tropical Cyclones,” discusses the impact of stalling storms throughout the North Atlantic tropical cyclone season and how findings will aid emergency mangers in affected regions by providing information that can be used to better prepare for future storms.

“Stalling tropical cyclones are those that sit over one spot for a long period of time,” said Trepanier. The speed of a tropical cyclone includes rainfall accumulation, storm surge, and exposure to high winds. When a storm stalls, these effects are even greater. This slowing prolongs exposure to intense conditions and can increase total damage. “Major concerns include continuous, unrelenting rainfall and inland flooding,” she added. As of mid-2022, tropical cyclones or their remnants have produced the seven costliest billion-dollar disasters in the United States.

The study found that stalls tend to occur in similar places over time and happen more frequently later in the hurricane season, around October, when compared to the middle of the season, in August. The risks from slow-moving storms are impacting growing communities along the United States Gulf Coast, which is the fastest-growing coastal region in the country, and Atlantic coastal zones. The population of these areas has increased by 7.7 million since 2000 to 59.6 million in 2016.

“All landfalling hurricanes are dangerous in their own way. Fast-moving storms like Beryl, Helene, and Milton carry their intensity and damage potential far inland, while stalling storms compound the damage in a more concentrated location,” Dr. John Nielsen-Gammon, Regents Professor at the Texas A&M Department of Atmospheric Science.

Figure 6 is a photo of stalling tropical cyclones and the intensity and location of stalls, color-coded by distance from the coasts of North and Central America and the islands defining the margin of the Caribbean Sea.

Figure 6: Stalling Coastal Tropical Cyclones. Intensity and location of stalls, color-coded by distance from the coasts of North and Central America and the islands defining the margin of the Caribbean Sea. Symbol sizes vary continuously with intensity. Sizes shown in the legend are examples.

Photo Credit: AMS Journal of Applied Meteorology and Climatology

Stalling storms that rapidly intensify are more dangerous that non-stalling storms that rapidly intensify because this leads to nearly stationary storms at higher and possibly unexpected intensities, extending exposure times and making evacuations more difficult. “Our biggest concern was about coastal stalls, such as Hurricane Harvey, because they can inundate communities with more rain than they can handle, which only further exacerbates additional issues like evacuation and medical transport,” Trepanier added.

In addition, tropical cyclones are expected to produce more intense precipitation due to the increased atmospheric water vapor as a response to climate warming and stronger upward motion in storms. Storm tracks that recurve or loop over a region can cause multiple landfalls and increase rainfall totals. The potential risk will increase with continued sea-level rise, population migration, and increasing sea surface temperatures in a warmer climate.

Tropical cyclones that stall reach Category 3+ strength (111 mph+) more frequently than tropical cyclones that do not stall because they tend to have longer life cycles. Trepanier and her team also suggest the number of stalls is increasing over time near coastal zones, indicating a heightened risk for those within coastal communities.

If stalling storms become more frequent throughout the basin, the risk of devastating conditions in areas impacted by tropical cyclones will increase. Trepanier and her research team noted the importance of continued research to attempt to further explain the discrepancies and geographic differences. Future research will focus on the mechanisms for stalling storms, as well as the accumulated rainfall to better
understand the risk faced by coastal communities.

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Contact Sarah Gaar Keller

LSU College of Humanities & Social Sciences

sarahg@lsu.edu

Abbi Rocha Laymoun

LSU Media Relations

abbirocha@lsu.edu