The Science Behind Long-Track Tornadoes: Lessons from the 2024 Houston-Port Arthur EF3

Long-track tornadoes, like the extraordinary December 28th, 2024 event in Southeast Texas, are among nature’s most incredible phenomena. Understanding what drives these rare storms isn’t just fascinating—it’s useful for storm chasers, meteorologists, and public safety.  However, most people don’t realize the complex relationship between storm dynamics and tornado longevity.

In this post, you’ll discover:

• The key atmospheric conditions that enable tornadoes to travel long distances.
• The role of storm propagation in shaping the behavior of the Houston-Port Arthur storm.
• Practical strategies for intercepting tornadoes safely and effectively.

By the end, you’ll have practical insights into the mechanics of long-track tornadoes and how to apply them to real-world forecasting and storm chasing. Let’s dive into a summary of this rare atmospheric event.

Event Overview

On December 28th, 2024, an exceptionally long-lived tornado carved a path of destruction across Southeast Texas. Starting just northeast of Smith Point, Texas, the tornado traveled an astonishing 48 miles to the south side of Port Arthur. With a width of up to half a mile and producing EF3-level damage, this tornado stood out as one of the most significant long-track events in recent memory, officially lasting at least 78 minutes.

The story might be even more remarkable. Evidence suggests the tornado may have started earlier, possibly west of Galveston Bay. The National Weather Service in Houston surveyed tornado damage near Dickinson, but the track was lost over Galveston Bay due to the water crossing. As a result, it’s unclear whether this tornado was continuous with the official start near Smith Point. If this connection holds, the tornado’s total path length increases to 64 miles, with a duration of 136 minutes.

There’s also speculation that the tornado may have continued beyond its official endpoint near Port Arthur. After crossing this area, the circulation moved over Sabine Lake and into the Sabine National Wildlife Refuge. With much of this region covered by water, it is not hard to imagine why the debris signature was lost. If the tornado is considered continuous from Dickinson to the wildlife refuge, the total path would extend to 77 miles, with an incredible duration of 169 minutes.

Though it falls short of the legendary Tri-State Tornado of 1925, which traveled 219 miles over 210 minutes, the December 28th tornado rivals it in terms of longevity. With less than 1% of tornadoes exceeding a 30-mile path, this event stands out as a rare and extraordinary display of nature’s power.

What Conditions Support Long-Track Tornadoes—and How Did Houston Measure Up?

Long-track tornadoes, like the one that struck Houston to Port Arthur on December 28th, 2024, present a fascinating meteorological puzzle. What allows some tornadoes to last so long and travel so far? While scientists have identified several contributing factors, the underlying physical mechanisms remain only partially understood (Straka et al., 2024).

Common Factors in Long-Track Tornadoes

According to Garner et al. (2021), specific atmospheric conditions are frequently associated with long-track tornadoes:

• Eastward-moving upper troughs
• Strong southwesterly winds throughout the vertical profile
• High effective bulk shear (deep-layer shear)
• Elevated storm-relative helicity
• Low buoyancy
• Fast storm motion

A BUFKIT model forecast near Houston at 3 PM showed that the storm largely met the conditions commonly associated with long-track tornadoes. The only exception was buoyancy, as its MLCAPE was relatively high (~2400 J/kg). However, Straka et al. (2024) noted that buoyancy is a poor predictor of tornado path length.

One promising predictor identified by Straka et al. (2024) is Bunkers right mover motion, which shows a strong correlation with tornado path length. The BUFKIT forecast estimated the storm's Bunkers motion at approximately 45 knots (52 mph) to the northeast, consistent with the typical motion for tornadoes with similar path lengths.

However, the actual storm speed differed significantly. The tornado officially traveled 41 miles in 78 minutes, translating to an average speed of 31 mph. If the extended path of 75 miles is considered, the speed drops further to just 27 mph.

Why Was the Real Storm Speed Slower?

The discrepancy lies in a process called propagation. While the storm’s upper-level winds carried it northeastward at a high speed, a phenomenon known as “back-building” slowed the overall system.

Back-building occurs when new storm cells form on the southwest edge of a supercell, along the same confluence boundary that initiated the original storm. This process effectively reduces the forward speed of the supercell. In the Houston storm, back-building slowed the storm’s motion by nearly 50%.

A similar scenario occurred during the May 27, 1997, event in central Texas, where a supercell propagated along a slow-moving cold front, producing multiple tornadoes, including the infamous F5 at Jarrell.

Why Did the Tornado Track So Far?

Scientists have long theorized that tornado longevity depends on maintaining a delicate balance between a storm’s inflow and outflow (Brooks et al., 1993, 1994a; Dowell and Bluestein 2002; Marquis et al., 2012).

Fast-moving storms typically help maintain this balance because higher tropospheric winds may generate a stronger rear-flank downdraft (outflow) that remains in equilibrium with inflow.

Slower storms, like the Houston-Port Arthur tornado, risk losing this balance due to stronger inflow and less intense outflow, leading to occlusion—a process that disrupts the tornado’s low-level circulation.

However, in this case, the back-building storms southwest of the supercell created a unique dynamic. These storms likely slowed the supercell’s forward motion, reducing storm-relative inflow. Simultaneously, they intensified the rear-flank downdraft via evaporational cooling, creating stronger outflows. The net effect was a sustained balance between inflow and outflow, which helped maintain the tornado’s longevity for at least 78 minutes—and likely longer.

The Houston-Port Arthur tornado serves as a vivid example of how complex interactions between storm dynamics and environmental conditions can produce rare and extraordinary long-track tornadoes.

Applying Storm Dynamics to Chasing

Understanding storm dynamics can improve storm chasing strategies and safety.

Adjust Your Intercept Strategy Based on Storm Speed

• For slower storms (<20 mph), you may want to intercept quickly, as their tornadoes are typically short-lived.
• For faster storms (>40 mph), you may want to position further downstream, as these storms are more likely to produce long-track tornadoes.

Account for Storm Propagation

• Propagation, where new storms develop on the rear or flank, can significantly alter storm motion. In the Houston-Port Arthur tornado, propagation caused the storm to slow and shift slightly. Unexpected propagation can deviate the storm from forecasts, potentially placing you in harm's way.

Use Radar Trends and Updraft Motion to Assess Tornado Longevity

• Real-time radar monitoring helps track storm behavior and identify changes in tornado path.
• Tornadoes moving with the main updraft are more likely to persist, while deviations may signal weakening or occlusion.

By applying these strategies, chasers and forecasters can make safer, more effective decisions when chasing tornadoes.

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Well, that's all for now.  Hope you enjoyed it!

- Gabe Garfield

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