NWS: Tornado popped up without warning


GRAND RAPIDS, Mich. (WOOD) – The National Weather Service Grand Rapids says the sudden nature of the tornado that touched down in Kent County Sunday night and the way the radar reads such tornadoes was the reason a tornado warning wasn’t issued to the public.

NWS Grand Rapids Meteorologist in Charge Dan Cobb said Monday afternoon the tornado, which he called a “spin-up,” popped up suddenly without any warning signs on the radar, which sweeps around every four minutes.

National Weather Service Grand Rapids Meteorologist in Charge Dan Cobb explains the path and rotation of the tornado. (July 7, 2014)
(National Weather Service Grand Rapids Meteorologist in Charge Dan Cobb explains the path and rotation of the tornado)

Cobb said the tornado, which the NWS categorized as a “high-end EF-1,” touched down about a minute after one pass of the radar and was weakening on the next pass.

“The next volume scan comes in and now you’re halfway down the damage path before we even see the signature, and then it takes a couple of minutes to issue a warning,” he said.

By the time the NWS was able to identify the tornado, Cobb said it was halfway through it’s six-mile, 10-minute-long path.

“They saw evidence on the second scan but it was already weakening, so they chose to go with a severe thunderstorm warning instead of a tornado warning,” he said.

Cobb said big storms usually start several miles above the ground and take time to touch down.

“The one thing we know is when it’s the larger tornado, the kind that would blow your house over, we’re very successful at detecting those and detecting those with fifteen minutes lead time,” Cobb said.

But spin-ups, Cobb said, start on the ground without any warning.

Cobb said the tornado, with winds reaching 100 miles per hour, appeared at about 10:20 p.m. just southwest of the M-6/US-131 interchange in Byron Township. The tornado then moved northeast through Kentwood and lifted off the ground around 10:30 p.m. south of 28th Street.

>>Photos: Kentwood tornado damage

While the NWS received no injury reports from the tornado, Cobb said many trees were down and the wind speed in the tornado was strong enough to peel shingles and siding off buildings, topple trailers and blow over sheds.

(A home damaged by a tornado that hit Kentwood. (July 7, 2014)
A home damaged by a tornado that hit Kentwood. (July 7, 2014)

Homes and buildings in some parts of the tornado’s path also saw heavy damage.

>>WATCH: Aerial view of Kentwood damage

Cobb estimated roughly 25,000 people were in the path of the tornado. However, he said if those people were inside a “structurally sound home,” they most likely were not in any danger.

The National Weather Service Grand Rapids will be upgrading its radar later in July, which will give its meteorologists an edge on seeing small, spin-up twisters.

 

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