At approximately 11:16am Wednesday morning, a tornado damaged homes in the city of Sardinia, Ohio (of north central Brown) County. The National Weather Service confirmed the tornado at 3pm this afternoon, but radar actually confirmed the tornado shortly after it occurred.
Here was the snapshot of radar reflectivity (the shower and storm mode) from the National Weather Service radar at 11:16am Wednesday:
The Tornado Warning is outlined in red. Note the weaker echoes between stronger echoes in the image above compared to the radar velocity (the “Doppler” part of Doppler radar) below:
In the highlighted area, the wind on the west side of the storm is moving away from the radar to the north of the storm (the red area), and the wind on the east side of the storms is moving towards the radar to the north of the storm (the green area immediately right of the red area). This is the circulation associated with the tornado.
How was it possible to confirm this tornado in real-time? See the correlation coefficient image from the National Weather Service’s radar at the same time:
That “cool” colored spot in the middle of red colors is a debris signature. It is very close to the rotation on radar and the hook seen in the reflectivity image. Correlation coefficient shows the correlation in shape and size of objects (raindrops, hailstones, etc) in each pixel. A high correlation (red colors) between objects suggests objects the radar samples are relatively the same size and same shape. A low correlation (cooler colors) suggests objects are of different shapes and sizes. In this case, the objects are pieces of trees, someone’s home, or crops being lofted into the air and being sampled by the radar. As a meteorologist, you hope you don’t see this. This signature (really, all three of them) confirmed the damaging tornado shortly after it caused damage.
See the comparison of the products:
The tornado had a damage path that was 1 mile long and up to 100 yards wide. The maximum wind was 75mph. This was the first confirmed tornado in Brown County since March 2, 2012; the 2012 tornado also went through Moscow, one of the deadliest Tri-State tornadoes in recent history.