Were There Really 5 Separate Tornadoes in Massachusetts on Saturday?

On Monday afternoon, the National Weather Service confirmed that two tornadoes touched down in Massachusetts on Saturday, September 6th in Paxton and Holden. They noted that the survey team was also in the process of investigating damage in Berlin and that the final report would be issued by Monday evening. When Monday evening rolled around, the service updated the total number of tornadoes to four, confirming twisters in Berlin and Stow.

At that time, the final report was delayed to Tuesday morning. When the final report was issued at 9:47am Tuesday, the final tornado count had jumped to five. After the report went final, there was some debate about if these were really five separate tornadoes. The debate focused on the fact that the tornadoes seemingly came out of the same supercell thunderstorm. Here's a deep dive into how this final number came to be.

Below: Damage points that were investigated by the National Weather Service. These points are marked by the small green triangles:

To begin to answer the question in the title, the basic timeline of events needs to be established. At 4:02pm, a tornado touched down in Paxton. This tornado reached wind speeds of 100mph, making it a mid-range EF-1. The tornado was likely on the ground for less than one minute, lifting by 4:03pm. At 4:06pm, the same thunderstorm dropped a tornado while it was still in Paxton. This time, it wasn't quite as strong, topping out with winds at 94mph. The tornado was again on the ground for no more than a minute, lifting at 4:07pm.

Just one minute later, 4:08pm, the storm dropped a tornado in neighboring Holden. The tornado was once again on the ground for a very short period of time, lifting by 4:09pm. Sixteen minutes later, a tornado along the same trajectory as the Paxton and Holden line touched down in Berlin. The tornado was on the ground for 2 minutes. The storm dropped a final tornado in nearby Stow three minutes after the Berlin tornado lifted, at 4:30pm. The twister was on the ground for three minutes. The Holden, Berlin and Stow tornadoes were all estimated to have winds at 104mph.

Below: Tree damage from Saturday's tornadoes:

The two Paxton tornadoes and the Holden tornado came from the same thunderstorm and were only spaced one minute apart. This means the initial tornado touched down, quickly lifted off the ground and touched back down. This occurred one more time before lifting for a longer period of time. This could have potentially been considered one "skipping or jumping tornado". A skipping tornado is often seen as a tornado that sees rotation weaken to the point that the tornado can't cause sustained damage before re-strengthening, or the tornado briefly lifts off the ground before touching down again.

Given the timeline described above, the three tornadoes in Paxton and Holden could be argued to be one skipping tornado given the extremely short time span between touch downs. With that said, when there's a distinct gap in the damage path, the tornado likely weakened and lifted off the ground before touching down again. Roger Edwards of the Storm Prediction Center once wrote in a tornado FAQ:

"Do tornadoes really skip? Not in a literal sense, despite what you may have read in many older references, news stories, or even damage survey reports. By definition, a tornado must be in contact with the ground. There is disagreement in meteorology over whether or not multiple touchdowns of the same vortex or funnel cloud mean different tornadoes (a strict interpretation)."

Below: Damage in Stow, Massachusetts on Saturday:

Mr. Edwards specially mentions older references and news stories. This is because, historically, skipping tornadoes were seen as one continuous tornado with a discontinuous damage path. However, with time and research, this thought process was put aside as the definition of a tornado was strictly about the tornado remaining in contact with the ground. This change in thinking has been considered for decades. In 1988, Charles Doswell wrote the following when discussing the issues of United States tornado climatology:

"The path length problem is another example of how our changing perceptions of tornadoes have resulted in a dilemma. Research constantly is increasing our awareness of how tornadoes behave and we no longer regard even the rather rare VLT tornado events with the same scientific credibility we once did. The National Weather Service procedure for determining path length states that tornado damage tracks with gaps of less than five statute miles should be combined into a single, "skipping" path. It should be noted that this procedure, until recently, accepted up to 10 mi gaps in a "continuous, but skipping" tornado.

The problem is that it is quite difficult to distinguish between long damage tracks resulting from a single tornado and those caused by a series of short-track tornadoes. Research has suggested that supercell thunderstorms commonly produce more than one tornado and that the tornadoes can be produced in rapid succession, with one still dissipating as the next in the series develops. Of course, gaps in the damage path well may be caused by intensity fluctuations (leading to the dubious notion of tornado "skipping") as well as by successive tornadoes."

Remember the above was written nearly 40 years ago. In current times, it is generally considered that gaps in tornadic damage are due to a "cyclic" thunderstorm. The official National Weather Service definition of a cyclic storm reads "A thunderstorm that undergoes cycles of intensification and weakening (pulses) while maintaining its individuality.

Cyclic supercells are capable of producing multiple tornadoes and/or several bursts of severe weather. When a cyclic storm produces multiple tornadoes, it's known as cyclic tornadogenesis. This creates what's known as a tornado family. The definition of a tornado family is "a series of tornadoes produced by a single supercell, resulting in damage path segments along the same general line."

When looking at the modern definition of what a tornado is, along with the phenomenon of tornado families, it becomes clear that is what occurred in central Massachusetts on Saturday. The same severe thunderstorm spawned all the tornadoes in rapid succession, within 30 minutes.

While questions remain about the three Paxton/Holden twisters, the Berlin and Stow tornadoes that formed afterward clearly paint a picture of a tornado family. With gaps in the three damage paths in Paxton and Holden, it's logical to see these as part of the cyclic storm process and tornado family. That would mean all three, despite occurring so close together, should be considered each their own tornado. This brings the total tornadoes to five individuals rather than one, two or three "skippers".