A hurricane is a large, rotating storm system that develops over tropical or subtropical waters, characterized by a low-pressure center, strong winds, and heavy rain. A tornado, by contrast, is a violently rotating column of air that extends from a thunderstorm to the ground. Despite their difference in size and origin, the answer to whether hurricanes produce tornadoes is yes. These massive tropical systems frequently generate smaller, highly localized tornadoes, especially as they make landfall.
The Driving Force Behind Tornado Formation
The primary atmospheric condition that allows a hurricane to spawn a tornado is vertical wind shear—the change in wind speed and direction that occurs with increasing altitude in the lower atmosphere. While hurricanes form in environments with low wind shear, their structure creates localized regions of extreme shear within their rainbands.
As the hurricane moves over land, increased friction from the rougher terrain causes the surface winds to slow down significantly. However, the winds just a few thousand feet above the ground maintain their high speed, dramatically increasing the vertical wind shear. This difference creates a horizontal, tube-like rolling motion in the air, known as horizontal vorticity.
When a thunderstorm’s updraft draws this horizontally spinning air upward, the rotation is tilted from a horizontal to a vertical plane. This process, combined with the instability and moisture present in the hurricane’s rainbands, concentrates the spin into the narrow column that becomes a tornado. The tornado often forms and dissipates quickly.
Where Hurricane-Spun Tornadoes Occur
Tornadoes associated with a tropical cyclone are most likely to form in the right-front quadrant. This quadrant is defined relative to the storm’s direction of motion and represents the area where the hurricane’s forward speed and its rotational wind are added together. The resulting wind maximum creates the greatest low-level wind shear and convergence, making it the most favorable zone for tornadogenesis.
Most of these tornadoes occur within the hurricane’s outer spiral rainbands. While the right-front quadrant carries the highest risk, tornadoes can occasionally be observed in the eyewall of a strong hurricane. The threat is not limited to the coast, as tornadoes can continue to form for up to 48 hours after a storm makes landfall and moves hundreds of miles inland.
Distinctive Features of Hurricane Tornadoes
Tornadoes generated by hurricanes possess several features that distinguish them from the strong supercell tornadoes commonly seen in the Great Plains. The vast majority of tropical cyclone tornadoes are relatively weak, typically registering as EF0 or EF1 on the Enhanced Fujita Scale. This means they cause light to moderate damage, such as peeling off roof surfaces or damaging shallow-rooted trees.
They are generally short-lived, often lasting only a few minutes and traveling short distances. Many of these vortices are spawned by “miniature” or low-topped supercells within the rainbands. These are considerably smaller and shallower than the classic supercells that produce the most violent tornadoes. This rapid development and short lifespan make them challenging for forecasters and the public to detect and react to.
Monitoring and Safety Measures
The National Weather Service issues Tornado Warnings for these events, which are often embedded within the broader Hurricane or Tropical Storm Advisories. It is important to treat every Tornado Warning seriously, even if the severe weather is part of a larger hurricane event. These warnings signal that a tornado has been spotted or indicated by radar and that immediate protective action is necessary.
Since hurricane-spawned tornadoes can form and strike with little advance notice, the most effective safety measure is to have a shelter plan ready. Upon receiving a warning, you should immediately move to an interior room on the lowest floor of a sturdy building, such as a closet, bathroom, or hallway, staying away from all windows. Utilizing a NOAA Weather Radio or reliable local alert system is crucial, as the heavy rain and noise of a hurricane can easily mask the visual and audible signs of an approaching tornado.