LITTLE ROCK, Ark. – March 1-7, 2020 has been declared Severe Weather Awareness Week by the National Weather Service (NWS) and Arkansas Department of Emergency Management (ADEM). Today’s topic of discussion is tornadoes.
A tornado is a rotating column of air that extends vertically from a cloud base to the ground. If it does not reach the ground, it is called a funnel cloud.
Tornadoes are violent and sometimes unpredicatble in their movement.
Forecasting for tornadoes has come a long way, though brief, weak tornadoes can still form so quickly that radar barely picks up its signature.
Arkansas has two severe weather seasons in which tornadoes most often form – spring and fall. It’s during these seasons when warm and cold air masses collide and have the most prevalent ingredients for tornado formation. Those ingredients include but are not limited to: moisture, wind shear (winds differing in speed and/or direction), instability (energy potential), lifting mechanism (cold fronts).
In 2019, 33 tornadoes occurred in Arkansas, which is the average count for the state. In fact, over 50% of the tornadoes from 2019 were actually reported in the month of May, which totaled 19 confirmed tornadoes.
Most tornadoes in Arkansas have been low-end or considered weak (below EF 2 rating).
According to data from the local NWS office, 772 tornadoes were spawned locally over the past 20 years, and 645 of them (about 80% of the total) were rated EF-1 or EF-1.
The number of confirmed tornadoes in Arkansas from 1950-2019 is up to 1,882. In 2020, there have been 10, so far.
Strong and violent tornadoes, rated EF-4 and EF-5, are pretty rare.
The last EF-4 tornado in the state was on April 27, 2014. It tracked through Pulaski, Faulkner and White counties, leaving a path 41 miles long and killing 16 people. According to data from the local NWS office, only two tornadoes were rated EF-4 other than the one confirmed on April 27, 2014.
When severe weather is in the forecast, it’s important to know the difference between critical weather terminology and what you should do for each scenario. A few terms in particular can cause some confusion when tornadoes are mentioned in the weather forecast.
A Tornado Watch means that conditions are favorable for the development of a tornado, but it does not mean that a tornado is on the ground.
- Preparations: review your severe weather safety plan, and make sure you’re staying weather-aware throughout the day.
A Tornado Warning means that a tornado has been sighted or has been indicated on radar. Danger may be imminent.
- Take action: seek shelter immediately.
The term Tornado Emergency is reserved for rare situations in which a tornado has been spotted visually or radar strongly suggests the ongoing destruction of a tornado (debris ball signature indicating debris being lofted into the air, picked up on radar technology). The NWS uses the term “tornado emergency” when there is a severe threat to human life and catastrophic damage is likely ongoing.
- Take action: seek shelter immediately.
If there is severe weather in the forecast, or if a tornado watch has been issued, follow these guidelines to prepare for a warning:
- Have a reliable way to receive tornado warnings (TV, NOAA Weather Radios, Weather Apps with alerts/notifications turned on, following professional sources on social media).
- Have a map readily available to reference cities and counties to reference where you are
- Charge electronic devices.
- Gather flashlights and batteries in case power goes out.
- Collect blankets, bike helmets, food to place in your safe space.
What to do when a tornado warning is issued?
- Seek shelter in a basement or storm shelter.
- No basement or storm shelter? No problem. Head to the lowest level and innermost room, putting as many walls between you and the outside as you can.
- Stay away from windows and doorways.
- Get low and protect your head using blankets or bicycle helmets if nearby.
- If you’re driving, pull over and seek shelter in the nearest building.
- Do not park under bridges or overpasses. They act as a wind tunnel, increasing the speed of wind underneath the road. Debris can get lodged in the “tunnel”, making it unsafe. Plus, emergency vehicles will need to get by and stopping here leads to traffic.
- If you live in a mobile home, even if it is tied down, you are not safe. Abandaon it immediately and seek shelter in sturdier building.
Many towns and counties have an outdoor tornado siren system that is used to alert the public when a warning has been issued. These sirens are only to alert people who are outdoors. Therefore, it is not a reliable source for tornado warning alerts.
The National Weather Service is the organization responsible for issuing the warnings, however, it has no control over the sirens. City and county officials make the call on sounding the siren.