No Advance Warning for Fatal Clarksville Tornado

Investigative Report  

© 2023 Mike Smith Enterprises, LLC

Update: December 20....

https://twitter.com/katymorganwx/status/1737602283494396379
Fox Weather, Nashville

The tornado's length turned out to be nearly 48 miles. Tragically, four people were killed by this storm. The NWS warning of this tornado left a lot to be desired. That story is told below. 

--- original posting ---

If I was a resident of Tennessee, I would be writing my congressional delegation demanding a congressional investigation into the National Weather Service's increasingly serious tornado warning issues -- and, that Congress create a Natural Disaster Review Board modeled after the National Transportation Safety Board.

Yesterday, I wrote about the tornado near Sharon, TN Saturday that was on the ground 13 minutes before a tornado warning was issued – even though it was an obvious warning situation. 

 

Today, I want to inform you that the fatal tornado that struck Clarksville, TN was not properly warned. Three people were killed and 62 injured. There was no tornado warning for Clarksville until after the storm was on the ground doing damage in spite of it being an obvious warning situation.  As tornado situations go, this was an easy one. 

 

I invite you to watch this heartrending interview conducted by Charles Peek of The Weather Channel. The man lost his brother-in-law in the storm. He stated there were just “seconds” between the tornado alarm activation and the beginning of the shaking of his building. 

As you'll recall from yesterday's investigative report, there was a tornado watch in effect for the area. There had also been a tornado warning to the west and southwest of Clarksville that did not include the metro area. Clarksville is an unusual metro area in that there is more or less continuous populated area from the word just south of the word "Clarksville" on the radar maps then on northwest to Ft. Campbell, Kentucky. 

The tornado was EF-3. EF-3 intensity is defined as a "strong" tornado by the National Weather Service (NWS). The NWS's published goal is to have a tornado warning out 13 minutes before a tornado develops. In this case, the "lead-time" (interval of time between when a warning is issued to when the tornado touches down) was, at best, negative two minutes as the tornado was on the ground before the warning was issued. A tornado warning for Clarksville should have been out no later than 1:25pm! I explain below. 

Here is the radar data from 1:19pm. Please click to enlarge. 

The left panel shows the reflectivity data -- the type of weather radar you see on television. There had been a hook echo minutes before, but the circulation of the "mesocyclone" (a small area of lower pressure and circular winds) had caused it to wrap around 360°. Note the lighter color in the middle, which was the likely location of the tornado. On the right is the tell-tale "tornado vortex signature" -- a sure indication a tornado is present. Had I been at the warning desk of my company (WeatherData, Inc.) I would have instantly issued a tornado warning for that area and points northeast to Clarksville and, perhaps, beyond.

The Nashville radar, given the tornado watch, should have been operating in the 80-second "tornado SAILS" mode. It was unfortunately operating in 3-minute mode, so we next data we have 1:22pm. 

At this point, a tornado warning is easy and straightforward. At upper left, we have a "hook echo" which has been a known tornado indicator since the 1950's. At upper right, you see the tornado's rotation on the Doppler wind display. This type of tornado signature has been known since it was discovered by NOAA's National Severe Storms Laboratory in the 1970's. At lower right, lofted debris from the tornado being detected by the dual-polarization feature of the radar. We've known about this signature for a decade. Given 2-3 minutes to prepare it, there should have been a tornado warning for Clarksville by 1:25pm at the latest.

That no tornado warning was issued until 1:45pm is utterly shocking. Words do not readily come to mind as to how bad a meteorological performance this was.

Note: The intermediate radar data between 1:22 and 1:41pm has been placed in a supplement below.

At 1:41pm, when the NWS said the tornado touched down just north of Sabre Airfield, there is a hook echo present (I enhanced it with a thin, dark line) which looks like an upside-down candy cane. On the right is the rotation from the tornado. At this point, the tornado is on the ground in the Clarksville area. Again, there is no tornado warning!

I saw this and did what I could to warn the people of Clarksville. But, it isn't my job to issue tornado warnings. It is the job of the NWS.

The NWS  tornado warning appeared on Twitter moments after I posted the above. While the 

warning says it was issued at 1:43, the times I can find on a couple of the communication channels say it didn't become available until 1:45pm. 

By 1:43, the radar again showed a hook echo (upper left), rotation (upper right) and considerable lofted debris (lower right). 

The Director of the NWS in October flippantly disregarded these concerns in a television interview last month -- calling them, "Monday morning quarterbacking." There are three more people dead and others in hospitals because his agency often cannot issue tornado warnings in a timely and accurate manner even when the evidence is overwhelming a tornado is present. 

From 2000 to 2011, the people of the United States could count on the National Weather Service for high-quality tornado warnings. It met its self-imposed goals of 13 minutes of lead-time (average) and accurately warned of 73% of tornadoes. This is no longer true. Since 2011,  average lead time has dropped to just over 8 minutes and the percent of tornadoes warned in advance has dropped to 59% -- in other words, the NWS has regressed to pre-Doppler quality warnings (statistically).

The non-political National Transportation Safety Board (NTSB) revolutionized safety in aviation. I believe a Natural Disaster Review Board (NDRB), if by law, was:

1. Non-political
2. Had to focus on natural disasters only and could not delve into side issues like climate change (the U.S. already has the National Climate Assessment and others for that),
3. Was located outside of Washington to minimize political interference, 
4. Was staffed with appropriate subject matter scientists and social scientists,
5. Had the power to subpoena all involved parties (including local and state emergency managers and private sector entities)
6. Was not an enforcement agency just as the NTSB is not. It would recommend best practices in the field of disaster forecasting and recovery. 

... could revolutionize the way we handle disasters in the United States, save billions, and, most importantly, save lives! Please write your congressional delegation....today. Otherwise, major unwarned tornadoes will keep recurring. I fear another Joplin (May, 2011, when the NWS and local emergency management made a number of mistakes) -- with 161 tornado deaths--  is inevitable. 

Supplemental Radar Data 

The software I use is called "RadarScope" and it displays professional-quality radar data. The data below are all of the frames between 1:22 and 1:41pm Saturday.