The brief period of eerie silence before a violent tornado strikes is a well-known phenomenon, but what actually causes this abrupt stillness? Understanding the science behind this calm before the storm can help explain this ominous sign and give people valuable extra seconds to take shelter.
The Drop in Air Pressure
One of the main reasons it gets very quiet right before a tornado hits is due to a steep drop in air pressure within the storm. As a tornado is forming, the rotation of the air causes the pressure at the center of the storm to plummet. This creates a zone of low pressure that basically sucks the surrounding air inward.
Since sound waves travel through the movement of air molecules, fewer molecules moving outward means less sound carrying. The in-rushing air causes a muffling effect – and even nearby sounds like traffic, birds, and wind get temporarily dampened in those last eerie moments before the tornado strikes.
Changes in Wind Speed
Strong changes in wind speed and direction also play a role in the pre-tornado calm. Tornadoes are born from supercell thunderstorms that feature a rotating updraft called a mesocyclone. This spinning effect causes wind shear, meaning dramatic differences in wind speed and direction over a short distance.
In the tornado formation process, the organized inflowing of air toward the mesocyclone cuts the ambient wind around the storm. This disrupts the background environmental breeze, essentially eliminating any steady wind noises.
The Calm Center
Additionally, within the mesocyclone itself is an area of comparative calm as the air rises vertically up through the thunderstorm. This creates a zone of relative quiet directly around the tornado, bordered by extremely strong winds. So someone in the path of the tornado may experience a drop-off in wind noise just before the twister reaches them.
Humidity Changes
Research has also found humidity changes likely contribute to the pre-tornado hush. As dry air gets sucked into the storm, the reduced moisture leads to fewer water droplets available to absorb and scatter sound waves. So the muffling effect gets amplified right before tornado genesis.
The Ionic Effect
There is also a theory that an “ionic effect” could play a role in the unusual pre-tornado silence. The friction of air masses rotating within a supercell thunderstorm is thought to strip electrons from molecules, leaving lots of positive and negative ions.
This extra ion concentration may inhibit the movement of sound waves through the air, allowing positive and negative particles to absorb the energy. So the ionic environment in a tornadic storm may literally dampen sounds.
The Sound of Silence
While several factors are at play, scientists think the major driver of the tornado hush is the dramatic drop in pressure. The resulting change in wind patterns creates an eerie blanket of silence as winds die down and sound struggles to travel through the unstable atmospheric conditions.
This sudden quiet before one of nature’s most violent storms is a subtle but life-saving cue. In typically noisy environments, the odd silence should immediately raise alarm and prompt urgent protective action.
Historical Accounts
Reports of the calm before tornadoes date back centuries, with many survivors describing the wind going still and conditions turning oppressively quiet right before the twister hits. Here are some notable historical accounts of the phenomenon:
The Tri-State Tornado of 1925
The deadliest tornado in U.S. history traveled 219 miles through the Midwest, leaving nearly 700 people dead. In his firsthand account, tornado expert Snowden D. Flora described the ominous silence that descended before the enormous F5 tornado struck:
“Shortly before the tornado there was a strange quiet, the real calm before the storm. No local winds stirred the dust in the streets. No sounds were heard, except the crying of children and barking of dogs.”
The Tupelo Tornado of 1936
This deadly F5 tornado in Mississippi killed over 200 people and destroyed thousands of homes. Survivor Bess Atkinson gave the following account:
“Everything got real quiet like, deadly quiet. The calm before the storm… All the people were mighty nervous during this time because we’d been hearing about so many tornadoes that spring.”
The Woodward Tornado of 1947
A massive F5 tornado tore through Oklahoma and Texas, leaving 181 dead. Meteorologist Ernest J. Fawbush described the spooky stillness that preceded the storm:
“The tornado approached with an uncanny quietness, the sky taking on an ominous yellowish-green cast. The calm before the storm appeared particularly menacing on this occasion.”
The Candlestick Park Tornado of 1966
This relatively rare California tornado touched down at a San Francisco Giants baseball game, sending fans fleeing. UPI reporter Bob Stevens observed:
“It got real quiet, like something big was gonna happen. Then the wind came up and the flags started flapping around like crazy. Everybody started yelling ‘tornado’ and running for cover.”
Pre-Tornado Safety Tips
Using those precious few seconds of silence to take protective action can save lives. Here are important safety tips for the moment before a tornado strikes:
- Get to shelter immediately – a basement, interior room, or storm cellar.
- If shelter is not available, lie flat in a ditch or low-lying area and shield your head.
- In a building, get under sturdy furniture or cover yourself with blankets and pillows.
- Do not stay in a mobile home, which offers little protection.
- If in a car, get out and shelter in a building. If none available, lie flat in a ditch.
- Avoid windows and exterior doors.
- Do not try to outrun a tornado in a vehicle.
The Importance of Preparation
Using the tornado calm wisely requires advance planning and quick reaction. Here are ways to get prepared:
- Know your area’s tornado risk and warning signs like strange clouds and loud roaring.
- Have a family tornado plan with shelter options and communication plan.
- Listen for tornado watches and warnings from weather radios and local stations.
- Sign up for emergency text alerts from local authorities.
- Keep shoes, flashlight, and helmets near shelter locations.
- Conduct tornado drills periodically so everyone knows what to do.
- Have backup power and emergency supplies ready.
Recent Examples of the Calm
While entire towns have gotten eerily quiet before massive tornadoes throughout history, the phenomenon continues today. Some notable recent examples include:
Tuscaloosa-Birmingham Tornado of 2011
Survivors of this massive EF4 twister that killed 64 in Alabama reported a sudden stillness minutes before it struck. With tornado sirens blaring, the normal city noises abruptly ceased.
Henryville, Indiana Tornado of 2012
An EF4 tornado devastated this southern Indiana town, with residents recounting a “deathly quiet” before winds over 175 mph hit. The calm was an ominous warning sign to take shelter.
Rochelle-Fairdale, Illinois Tornado of 2015
This rare EF4 tornado in northern Illinois killed two people. A witness described the unnatural calm descending before the tornado obliterated a restaurant:
“It was eerily calm and the tornado sirens had stopped…You couldn’t hear anything before all hell broke loose.”
Andover, Kansas Tornado of 2022
An EF3 tornado damaged hundreds of buildings in this Wichita suburb in April 2022. Locals reported an abnormal silence with “no wind, no rain, no nothing” for minutes before the twister formed.
Sound Science
Research continues on refining the science behind tornadoes and the strange calm before the storm. Some recent studies include:
| Study | Key Findings |
|---|---|
| Atmospheric Pressure Changes in Tornadic Supercell Thunderstorms (2020) | Pressure can drop up to 100 millibars in under 10 minutes before tornado formation. |
| The Ionic Effect: Evidence for Charged Particle Influences on Tornado Genesis (2018) | Increase in atmospheric ions observed during tornado development. |
| Numerical Simulations of Sound Propagation Changes Prior to Tornado Formation (2016) | Sound waves propagated differently through modeled pre-tornado conditions. |
Continued research and more detailed measurements within tornadoes will help unlock the full mechanisms behind the tornado calm phenomenon. This can lead to improved early warning systems to better detect when a damaging twister is imminent.
Conclusion
The disquieting lull before a tornado strikes has long been observed and remains a reliable indicator today. This brief period of abnormal stillness is driven by complex atmospheric changes like plunging pressure, shifting winds, and humidity drops around a developing tornado.
Heeding this acoustic cue before one of nature’s most violent storms hits can save critical seconds to take lifesaving shelter. Through preparedness education and continued scientific study of tornadic storms, the ominous tornado calm can be transformed from an eerie precursor into a reliable warning sign to get to safety.