On Monday, several large, dangerous tornadoes ripped through southwest Oklahoma. Two of Oklahoma’s 120 automated weather stations in its “Mesonet” stood in the way and were taken out. But they recorded valuable data in the process demonstrating jaw-dropping pressure drops and wind accelerations.
Shortly after the tornadoes toppled the instrument sets mounted on 10 meter towers, the Mesonet blog known as the Ticker dispatched this report:
Never in Mesonet history has a site been leveled by a tornado, but it appears to have happened twice [Monday]. We have eyewitness reports from the OSU Caddo Research Station that our Fort Cobb Mesonet station is laying on the ground, covered by debris. That debris includes an irrigation pivot from a nearby field.
Our Mesonet station at Tipton, located on the OSU Agronomy Research Station, appears to have also been leveled. The site is usually visible from the roadway, but eyewitnesses report they can no longer see it.
Although these stations were knocked out, scientists were hopeful data would be recovered and wasted no time in an effort to fetch them.
The Ticker explained:
We have Mesonet technicians en route to both sites this morning to attempt a data retrieval and see if the tornadic winds were recorded.
Tuesday evening, the Mesonet Facebook page reported the retrieval mission was successful. And the data recovered were amazing, as summarized:
Tipton recorded a wind gust of 86.4 mph before it was destroyed. The anemometer has yet to be found. The site experienced a pressure drop of 47.16 mb in 1 minute, recording a low of 913.47 mb!
Fort Cobb recorded a wind gust of 91.4 mph before it was driven into the ground. It had a more gradual pressure drop of 14 mb, recording a low of 944.81 mb.
For perspective, when a large storm like the Alaska “Snowicane” deepens 30 mb or more in 24 hours, it is considered a “meteorological bomb”. In the Tipton tornado, the pressure dropped practically 50 mb in a minute!!!
(Note, coincidentally, the 944 mb pressure measured in Ft. Cobb is about the same as the minimum pressure observed in the Alaska Snowicane)
Today, the Mesonet Facebook page offered additional data, showing an incredible burst of wind in Tipton, before the station collapsed:
...the tornado hit fast and furious. Wind gusts went from 30 mph at 2:55 PM to 54 mph at 2:56 PM to 86 mph at 2:57 PM. Large debris took the tower down before we were able to capture the next observation of wind data.
From the YouTube caption: “Intercept of a strong tornado near Tipton, OK on November 7, 2011 in the Dominator 2! Storm chasing Andy Gabrielson rolls his vehicle in the outer circulation of the tornado. Thankfully he was okay and resumed the chase, and there was no loss of life from this tornado.” Posted by TornadoVideos.net
While it was the first time Mesonet stations had been leveled by tornadoes, it was not the first intercept. On May 24 of this year, a Mesonet site northwest of El Reno, Ok. recorded a wind gusts of 151 mph from a tornado but most instruments “remained operational.” The 151 mph gust was the highest on record for the state, and just one of many weather (and natural event) records set in Oklahoma in 2011.