Tornadoes are one of nature’s most violent and destructive forces. These violently rotating columns of air extend from thunderstorms down to the ground, capable of causing catastrophic damage along their path. A key aspect of tornadoes is that they are always in motion, traveling along the ground at speeds typically between 30 to 125 mph. However, very rarely, a tornado can form without any horizontal movement, remaining stationary over one area. But what exactly happens when a tornado just stays put in one place rather than traveling? Let’s take a closer look at stationary tornadoes and the impacts they can have.
What is a stationary tornado?
A stationary tornado, also sometimes called a stalled tornado, is a tornado that exhibits little to no horizontal motion. While most tornadoes travel forward as they swirl, a stationary tornado spins vertically over one fixed spot. Meteorologists define a stationary tornado as a tornado that moves less than 5 mph horizontally. This is an unusual phenomenon, as tornadoes are synonymous with destructive forward motion. Less than 1% of observed tornadoes are considered stationary.
Causes
Stationary tornadoes form under very specific atmospheric circumstances. There are two key ingredients that can lead to the development of a non-moving tornado:
- Weak steering winds – Tornadoes are pushed along by the prevailing winds in the atmosphere around them. Weaker steering winds prevent the tornado from being driven horizontally across the landscape.
- Boundaries – Stationary tornadoes often form along persistent boundaries between areas of contrasting temperatures and moisture. This includes fronts, drylines, and outflow boundaries from prior convection. These boundaries provide continuous horizontal vorticity that keeps feeding the vertically oriented vortex.
When steering winds are diminished and/or persistent boundaries are present, there is nothing to physically relocate the tornado away from its initial point of formation. With a continuous source of rotation along the boundary and an absence of steering, the tornado remains anchored in place.
Famous Examples
Some notorious historical examples of quasi-stationary tornadoes include:
- The Tinker Air Force Base tornado – On March 26, 1948, a tornado formed over Tinker Air Force Base near Oklahoma City, Oklahoma where it remained nearly stationary for 37 minutes. It was the longest-duration tornado on record at the time.
- The Windsor Locks tornado – An F4 tornado struck the town of Windsor Locks, Connecticut on October 3, 1979. It moved less than a mile over 38 minutes, doing tremendous damage to the Bradley Air National Guard Base.
- The Hesston-Goessel tornado – On March 13, 1990, an F5 tornado remained nearly stationary for 18 minutes over the neighboring farming communities of Hesston and Goessel, Kansas. It killed 2 and injured 200.
These slow-moving to stationary tornadoes produced incredible damage because they stayed focused over one area for an extended period of time.
Impacts on Severity
The lack of forward motion is a major factor in making stationary tornadoes particularly dangerous and destructive. The primary impacts include:
- Focused damage – Since the vortex stays centered over one area, damage becomes extremely concentrated. The same structures take a direct hit for an extended time, leading to extreme localized destruction.
- Duration – Stationary tornadoes typically last longer than moving ones, inflicting damage over a greater period of time. The record for longest lasting tornado is held by a stationary tornado.
- Intensity – The focused nature of stationary tornadoes can allow them to gain strength over time. Wind speeds often intensify the longer the vortex remains in place.
The combination of these factors allows stationary tornadoes to inflict severe damage typical of only the strongest and largest moving tornadoes. Areas suffering direct hits can be almost completely obliterated by these persistent, concentrated vortices.
Records
Here are some record extremes related to stationary tornadoes:
- Longest duration: Tinker AFB tornado, March 26, 1948 – 37 minutes
- Highest wind speed: Bridge Creek-Moore, OK tornado, May 3, 1999 – 301 mph
- Greatest damage: Jarrell, TX tornado, May 27, 1997 – F5 damage inflicted
The Bridge Creek-Moore tornado actually slowly cycled between stationary and very slow movement, allowing it to become the most intense tornado on record when it struck Moore, Oklahoma.
Predicting and Preparing
Forecasting stationary tornadoes presents challenges, but increased radar ability has improved detection of potential precursors:
- Boundary detection – High-resolution Doppler radar can now spot small-scale boundaries for possible vortex initiation.
- Storm relative velocity – This identifies areas where inflow into a thunderstorm opposes the mean wind, signaling possible low-ground-relative winds.
- Debris detection – Identifying lofted debris indicates tornado formation and lack of motion.
Once a stationary tornado is identified, effective emergency communication is critical, as motion cannot be used to determine the storm’s path. Residents must seek shelter immediately, preferably a tornado-rated safe room, to protect themselves from the localized threat.
Conclusion
Stationary tornadoes represent an especially dangerous tornado hazard. Their lack of motion concentrates damage over one area for an extended time period, which can have catastrophic impacts on any structures and lives in their path. While rare, knowledge of the threat posed by these unmoving vortices can help guide preparedness and protective actions to save lives when they do sporadically occur. Advanced forecasting methods and urgent communication of tornado behavior remain key to mitigating potential harm. Although all tornadoes warrant vigilance, it is wise to be particularly wary of any warning for a tornado at risk of stalling over a community.