On Saturday evening, the National Weather Service posted in a tornado warning that a "radar-confirmed tornado" was on the ground near Chaplin, Connecticut. On Monday afternoon, the National Weather Service announced that there was no tornado in Connecticut on Saturday. So what exactly happened?
First, a radar-confirmed tornado is when there are very strong indications that a tornado is on the ground on radar, but a trained storm spotter has not been able to visually confirm the presence of a tornado in person. This occurred on Saturday evening when a clear "hook echo" could be seen on radar during this storm.
This feature indicates that the storm is rotating. Just before 7:30pm, a tornado warning was issued for the storm as it was capable of producing a tornado. Just after 7:30pm, the tornado warning was updated to announce that a radar-confirmed tornado was on the ground. This update came thanks to a tornado debris signature (TDS) that appeared on radar. A TDS is an area of high reflectivity on a weather radar caused by flying debris. This debris can only show up on radar from the power of a tornado.
Example of a TDS. You can see different coloring in the black circle, that indicates a tornado. This example is NOT from the alleged TDS from Connecticut's storm Saturday night:
At this time, numerous photos and videos began to emerge from area residents depicting a large funnel cloud near Manchester and moving eastward toward Killingly. This increased confidence that a tornado was, indeed, on the ground.
The tornado wasn't confirmed to be on the ground as a storm spotter still hadn't verified its existence. The tornado warning, which was originally posted to expire at 7:45pm was extended to 8:15pm. The warning would be canceled before it's 8:15 end time as the indication of rotation was growing weaker on radar.
The National Weather Service visited the area Sunday morning to survey damage to determine the details about the tornado. This occurs after every tornado report. This is how tornadoes are often confirmed. This is also how tornadoes are assigned an "EF" number. Surveyors assess damage in the area and determine how strong the tornado was.
Surveyors assessed the area around where the tornado would have been in Chaplin, Hampton, Brooklyn, Plainfield and Killingly, but could not find any damage consistent with a tornado. Tornado damage will feature trees broken in all directions, whereas straight-line wind damage will see trees broken all the same way.
Only straight-line wind damage was found in Manchester. On Saturday evening, New England Storm Center posted initial damage reports from the area of the tornado. We made it a point to say that those reports were not confirmed to be connected to the alleged tornado.
National Weather Service surveyors were on site all day to be as thorough as possible. The Civil Air Patrol even flew over the entire area to try to spot tornado damage from the air. Despite this, no tornado-like damage could be seen.
The National Weather Service said in their statement:
"The National Weather Service had cited the presence of what is known as a tornado debris signature (TDS) on radar. However, upon further review, the signature was not well-defined and likely was not a true TDS. Doppler spectrum width was low in that area, which is indicative of minimal turbulence. That is not characteristic of a tornadic signature."
That statement solves why the tornado was radar-confirmed. The other main piece as to why a tornado was initially confirmed was the number of photos and videos of a clear funnel cloud. Further review of these images would prove to show a large funnel cloud that wasn't quite touching the ground. When a funnel cloud gets close to touching the ground, it can be difficult to tell if it is actually making contact with the ground, especially from a distance. Of course, a funnel cloud must contact the ground to be a tornado, no matter how close it may get. Even if it's just a foot off the ground, it's still a funnel cloud, not a tornado.
The National Weather Service would conclude their report with:
"Our conclusion is that a funnel cloud traversed eastern Connecticut. It came dangerously close to touching down but never did so."
The straight-line wind damage in Manchester was from a microburst that contained winds estimated at 70-80mph.
Here's the National Weather Service's full statement:
During the evening on July 29th, doppler radar indicated a rotating thunderstorm that moved across central and eastern Connecticut between 630 PM and 8 PM. The rotation aloft became strong over the Chaplin area, prompting the issuance of a Tornado Warning. There were numerous videos and photos of a large funnel cloud beginning in Manchester and working its way eastward to Storrs and continuing on to Killingly, near the Rhode Island border. The National Weather Service conducted a survey throughout the towns of Chaplin, Hampton, Brooklyn, Plainfield, and into Killingly, incuding the Wauregan and Danielson areas. The Connecticut Division of Emergency Management and Homeland Security accompanied us on the survey. We scoured that region and were unable to find any damage consistent with a tornado. A drone video from the southern end of Pine Acres Lake in Hampton showed a couple of trees downed (time of downing unknown). To be more certain that we were not missing something, the Civil Air Patrol flew several flight paths across that entire region, beginning back in the Coventry and Mansfield areas. From the air, no damage was spotted anywhere along the entire route. During the event, the National Weather Service had cited the presence of what is known as a tornado debris signature (TDS) on radar. However, upon further review, the signature was not well- defined and likely was not a true TDS. Doppler spectrum width was low in that area, which is indicative of minimal turbulence. That is not characteristic of a tornadic signature. Our conclusion is that a funnel cloud traversed eastern Connecticut. It came dangerously close to touching down but never did so.
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