Last year I was studying Atmospheric Science at the University of Wisconsin – Madison in the US. One of the teaching assistants in my department was a Leeds alumni doing his PhD in tornado genesis. The weekend of the 8th – 9th May 2016 a tornado outbreak was predicted in Oklahoma. Never having experienced any extreme weather before, I thought I couldn’t turn down an opportunity to go chasing with an experienced storm chaser! We hired a car and a group of us drove 1000 miles south to Oklahoma.
In the car we had a couple of radars showing variables like the winds and reflectivity. This let us monitor several supercells and decide which were most likely to drop a tornado. Once we had chosen a storm cell and were chasing it everyone had to be doing their separate jobs. The first of my jobs was monitoring the reflectivity radar to keep an eye on the ‘hail hole’. In the core of the storm precipitation is extremely heavy and hail is produced that can be the size of a tennis ball. This would be very dangerous to be caught in as it would completely wreck the car. Precipitation that heavy is also very challenging to drive in as visibility is so low. There’s an image below showing the radar image for one of the storms we chased, and the tornado would be in the yellow band directly in line with the leftmost pink spot. The reds and pinks are the heaviest precipitation.
Radar Reflectivity Image of a Supercell Thunderstorm over Garvin County, Oklahoma. 3:50pm May 9th 2016. (from https://www.weather.gov/oun/events-20160509-ef4tornado)
The second of my tasks was helping with the road maps. We were in rural Oklahoma and roads were few and far between, once you’ve committed to a road you’re going to be on it for several miles before there’s a turning off. It’s not too difficult to predict the track of a tornado but they are moving at around 30 miles per hour. Therefore in the Northern hemisphere it’s safest to be to the north or the east of the tornado. Driving in heavy rain on poorly maintained roads it can be difficult to go much faster than this.
The first day of chasing was slightly disappointing. The supercell we selected did drop a tornado to chase but the tornado itself was rain-wrapped. This meant we could barely see it! The second day was much more successful. Late afternoon/early evening several supercells produced a dozen tornadoes, some long-lived and damaging. One of the tornadoes we chased was an EF4 (the scale runs 1-5). The path length was 9 miles long and I was shocked at some of the damage. Trees were uprooted, several homes were destroyed and 1 person died. I was too busy to get any decent pictures of the tornado, except of the hail on the ground afterwards and some cool mammatus clouds, but I’ve included here some of the videos and photos other chasers took.
(Tornado photos taken from http://kfor.com/2016/05/10/pictures-videos-of-tornadoes-that-tore-through-oklahoma-may-9th/)
I’d got slightly bored of all the maths and computer modelling we did in class and was losing interest in atmospheric science. But storm chasing was a real adrenaline rush and reminded me how exciting I find extreme weather. It played a big part in my coming back to Leeds to study a Masters in Meteorology and Climate Science.
Written by Hannah Thorpe – University of Wisconsin – Madison