December 10 is a day Kentuckyans will not soon forget after a destructive, long-track tornado ripped through our state. Experts met recently to discuss a measured gust of wind that occurred that night and how it compares to state records. On the night of December 10, two Kentucky Mesonet weather stations were in the path of a tornado. This means that the wind speed around this tornado was measure instead of valued, an important distinction when keeping official records. Very often, in severe weather, trained observers send reports of estimated wind speeds. This is why storm spotter training through the National Weather Service is so important, because it tells us that the spotter’s estimate is close to accuracy and helps the spotter estimate correctly.
But back to the story – the old record for the strongest wind gust in Kentucky was 100.8 mph, also measured by a Kentucky Mesonet station in Calloway County. This happened on April 26, 2011. Fast forward to December 10, 2021 and, “the storm struck at least two Kentucky Mesonet sites, producing measured wind gust speeds greater than any previously experienced in Kentucky” , according to the report published at the end of this meeting. of experts.
The first Mesonet station is in Graves County, 5.7 miles southwest of Mayfield. The white dot above represents that station, the color shading is the tornado’s track and the wind strength. Blue corresponds to winds of magnitude EF-0, green to EF-1 and yellow to EF-2. This station measured a wind gust of 107.1 mph at 9:24 p.m. central time on the night of December 10. This wind sensor is 10 meters above the ground, or almost 33 feet. You can see this data in the graph below, but keep in mind that wind speed is measured in meters per second and then converted to miles per hour. The station actually recorded a gust of 47.89 m/s for at least three seconds.
The report adds that this gust of wind could be from the tornado itself or “perhaps a downdraft from the rear flank, based on analysis by NWS Paducah.” This gust was strong enough to break the old record, but the storm continued.
The next station in the tornado’s path was in Caldwell County, 1.5 miles southeast of Princeton. The storm arrived there at 10:25 p.m. central time, about an hour later. This station gives even more interesting data because there was a wind sensor at 10 meters (like the first one), but there was a second wind sensor only 2 meters from the ground (closer to 6 feet) where we feel really the wind here on the ground. The upper sensor registered a 75 mph gust of wind before it stopped reporting. The lower anemometer continued to report and measured a wind gust of 120.1 mph as the storm passed.
Since it was such a strong gust, all equipment was checked after the storm passed and appeared to be functioning properly. In fact, the tower containing this equipment was damaged during the storm, necessitating additional checks on the accuracy of the sensor which continued to report. Again, this measurement was taken in meters per second, so the official measurement is 53.7 m/s. These data demonstrate the importance of the Kentucky Mesonet program and the importance of placing measurement sites across the Commonwealth.
It’s hard enough to dispute the data when it’s been recorded so well, but there is a question about the difference between gusts of wind and tornado wind. During this meeting, “the team discussed whether a wind speed measured in a tornadic circulation was appropriate to be counted as a record gust of wind. Although the term ‘wind gust’ may initially conjuring up the thought of straight-line winds, she felt that a measured wind speed, regardless of weather cause, was appropriate for this class of record wind.” All that to say, we have a new record for strongest wind gusts in Kentucky: 120.1 mph on December 10, 2021; a day (or night) we won’t soon forget.
Image credits: State Climate Extremes Committee and National Oceanic and Atmospheric Administration