Analyzing Radar Data from Sunday Night’s Storm

Posted at 7:46 AM, Jul 07, 2014
and last updated 2014-07-07 10:09:50-04

KENTWOOD, Mich. (July 7, 2014) — As residents, officials, and on-lookers continue to learn more about the damage from Sunday night’s severe weather, one of the most interesting questions after an event like this one is always whether or not the storm contained a tornado.

To be clear, the final answer to that question is of little importance — the damage has been done, tornado or not.  But analyzing some of the radar images from the storm can help us to recognize what may have occurred, in order to better forecast it the next time we find ourselves in a similar situation.

From a meteorological standpoint, this is some of the best data we could ask for, as the area of damage is located very close to the radar site at the Gerald R. Ford International Airport.  That means the radar beam is able to see the very lowest levels of the storm.

Here is the area of focus, where a large majority of the wind damage has been reported so far:

The most heavily damaged area, 7/6/14

It’s bounded roughly by Burlingame Ave. on the west, 64th St./M-6 on the south, Kalamazoo Ave. on the east, and 44th St. on the north.

From that same perspective, check out the Doppler radar storm-relative velocity image at 10:22 P.M.:

Storm-relative velocity, 10:22 P.M. 7/6/14

The velocity data gives us information about the movement of air/raindrops within a storm.  Green indicates movement toward the radar, red is away from the radar.  The above image shows that right around U.S. 131 and M-6, there was a tight circulation that developed very quickly.  The estimated winds here are already in excess of 65 mph.

The next radar scan at 10:27 P.M. shows that circulation continuing northeastward, to around 52nd & Eastern Ave.:

Storm-relative velocity, 10:27 P.M. 7/6/14

Note that much of the most intense damage correlates very closely to the track of that circulation.  Not only that, but in the reflectivity image taken in the same sweep, you see a big “ball” of something near that same location:

Base reflectivity, 10:27 P.M. 7/6/14

The National Weather Service suggests that this indicates the radar beam picking up debris blown into the air by the high winds.

However, this damage was extremely localized, and you can see that by 10:31, the circulation with the storm had become much less organized:

Storm-relative velocity, 10:31 P.M. 7/6/14

The National Weather Service issued its own brief analysis of the storms on its website early Monday morning.  Survey crews will be out to check out the damage and make an official determination of its cause; FOX 17 will have that information later in the day.  First glances at the damage and radar data suggest that it very easily could have been a tornado around the Kentwood area Sunday night.