Friday, July 30, 2021

Bensalem Tornado: Another Dangerous National Weather Service Warning Miss


As many of you know, The Washington Post on May 21 published an essay of mine that documented the deterioration in the National Weather Service's tornado warning program. Subsequent events, some documented in this blog, have confirmed this dangerous trend of the past ten years. 

Last night was one of the worst -- and most dangerous -- misses yet. It occurred with the Bensalem Tornado which struck a northeast suburb of Philadelphia with little warning. There were five injuries (severity unknown) and the damage was at least F-2 intensity (addition: NWS rated the tornado EF-3). Here is the sequence of events (all times EDT):

At 6:49pm, there was rotation in the supercell's appendage in the north Philadelphia suburbs. I was shocked a tornado warning had not been issued.
So, I outlined the rotation and advised people from there to Bensalem and beyond to keep an eye on the storm. Remember: it is the core mission of the National Weather Service to issue tornado warnings to the public, not individual citizens'.

At 7:03pm, the Doppler wind data shows a classic tornado signature (circled). Yet, there was no tornado warning at this time. [Note, the time on the image is Central time because I live in Wichita.]

At 7:07pm, the National Weather Service finally issued a tornado warning for Bensalem (see list of cities at the bottom). 
The National Weather Service's tornado warning was issued 18 precious minutes after the tornado's signatures first appeared on their radar. And, the warning was not issued until 3 minutes after the tornado was on the ground, doing damage. 

An experimental program (below) estimates this tornado was in the EF-2 to EF-3 intensity range. That seems consistent with the damage photos I have seen. I'm sure the NWS will do a damage survey and make a final determination. 

Other evidence says the tornado was a surprise. This tweet contains a video of the tornado as it moves in front of the driver at a toll booth. In the video, you do not hear the Wireless Emergency Alert (WEA) tones, meaning a tornado warning was just issued, until after you see high winds and a large electric highway sign blown about by the tornado. 

At a car dealership (see photo at top), this video shows the employees are having fun until the tornado strikes. With the intensity of the flying debris, it is a miracle no one was killed.

What is so perplexing about the lack of advance warning is that this tornado warning was straightforward, even easy. It presented itself as the type of tornado we learn about in college. Ten years ago, the National Weather Service would have issued a timely warning. 
ABC6, Philadelphia
As I said in my Washington Post piece, I don't know why the tornado warning program of the National Weather Service has deteriorated to the extent that it has during the last decade. It could be lack of training, retirements causing valuable experience to be lost, or any number of causes.

So, far the NWS has shown little interest in attacking or even acknowledging the problem. This is why the United States desperately needs a National Disaster Review Board. If you are so inclined, please forward this to your congressional delegation. Thank you. 

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