DETROIT – There are a lot of lessons learned from Saturday’s tornado event across western Michigan. I’ll get to those lessons in a moment but, first, my colleagues at the National Weather Service in Grand Rapids have released some additional information about what actually happened.
The weakest tornado, an EF-0 rated twister (winds in the range of 65-85 mph) is noteworthy because it hit in the Grand Rapids city limits. This particular tornado was very brief, and touched down near Perkins Avenue NE between Leonard and Knapp street NE. Property damage was mostly from fallen trees.
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An EF-0 tornado touched down near 44th Street and Ivanrest Ave. SW in Grandville and continued on the ground along a varying path through Grandville and Wyoming, before lifting near the intersection of Nagel Avenue SW and Chicago Drive SW.
Though the tornado remained west of US-131, it did zigzag across a number of major roads/intersections in the Grand Rapids metro area. Winds in this tornado are estimated to be 80-85 mph. Along the path, hundreds of trees were damaged or knocked over resulting in tens of thousands of power outages. Many homes and a number of vehicles were damaged from fallen trees.
Below are some images of tornado damage in Ionia and Montcalm Counties from the National Weather Service Grand Rapids.
A couple of notable locations the tornado moved through include the Wyoming Middle School football field where a set of football field goal posts were bent by soccer goals...and Battjes Park and Prairie Park where a number of trees were damaged or uprooted. Straight line winds also occurred in Kent County to the east of the path of the tornado.
These straight line winds (which may have approached 100 mph at times) occurred mainly from near the intersection of M6 and Wilson Avenue SW through East Grand Rapids. Notable locations that were impacted by straight line winds include Ironwood Golf Course, Maple Hill Golf Course and Pinery Park.
The NWS damage survey confirmed an EF-1 tornado in Ionia and Montcalm Counties. Tornado damage began just east of the small town of Orleans, and moved northeast where it crossed M-44, bringing down several large trees. One of the trees fell on a house. The tornado then crossed West Long Lake Road, where the concrete block wall of a garage was blown out and shingles were peeled off the roof of a house. Peak winds were estimated at 90 mph. The twister was on the ground for eight miles, with a path width of around 100 yards.
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The final tornado could end up being multiple tornadoes, depending upon if the National Weather Service can determine if the debris path stops at any point and then resumes, and they won’t be able to do this until Tuesday. Here is what we know thus far about this twister that impacted Van Buren, Allegan and Ottawa counties:
Van Buren County: A 50 to 150 yard-wide path of EF-1 tornado damage extended from Bangor northeast to Grand Junction, continuing into Allegan County. Winds of 90 to 110 mph were estimated from damage along its path.
Allegan County: A 50 to 100 yard-wide path of EF-1 tornado damage extended from 118th Avenue southeast of Fennville northeast to the Ottawa County border, continuing into Ottawa County. Winds of 90 to 100 mph were estimated from damage along its path.
Ottawa County: A 50 to 100 yard-wide and 3.5 mile long path of EF-1 tornado damage extended from the Allegan County border to 8th Avenue north of Perry Street. Winds of around 90 mph were estimated from damage along this path.
Lessons learned:
This was not a classic tornado situation. In fact, although western Michigan was originally in the slight severe weather risk area, the Storm Prediction Center actually downgraded the area to a marginal risk. And the weather we saw developing on radar initially didn’t look all that imposing.
However, some very small scale dynamics developed that, combined with some low-level storm wind interaction, spun up these twisters. No, we meteorologists did not begin the day on Saturday thinking that we’d get tornadoes anywhere in Michigan.
However, there was still a marginal risk, and that doesn’t mean no chance of severe weather. Rather, it means very sparse coverage of any severe storms that do develop. Please respect ALL storms – even those that don’t appear severe – as lightning can be deadly, and we just had our state’s first lightning fatality this past Friday, when a 21-year old woman standing outside next to her cabin on Presque Isle was struck. She’s the twenty-ninth person nationally killed by lightning this year.
This further emphasizes why you should have a NOAA Weather Radio. I’ve said it before and I’ll say it again: a weather radio is like a smoke detector for severe weather. It sits silently in the corner of your room, until a piercing siren tells you that something important is going on that you need to know about.
Finally, Saturday’s weather situation once again shows how Doppler Radar can sometimes confirm a tornado before we even get any ground truth from spotters or the public. Take a look at this image that I tweeted (@PGLocal4) Saturday afternoon during the event.
This radar product is called Correlation Coefficient (“CC”) and, to keep this simple, it tells us about the uniformity of whatever targets the radar is detecting. Raindrops and snowflakes are pretty uniform targets.
However, tornado debris in the air – branches and leaves, shingles, boards, etc. – have very different shapes, and the radar detects that. I saw the sudden development of a much lower CC value and, knowing where this was in relation to where I was seeing rotation in the velocity data (not pictured), was a strong indication to me that a tornado was on the ground and lifting debris into the air.
In my next tweet a few seconds later (also not pictured), I said: "Here’s a closer look…likely a Tornado Debris Signature…showing debris in the air."
This shows you how we meteorologists with dual polarization radar training can, in some situations, detect a tornado before we even get visual confirmation. Of course, radar won’t show us every tornado…the very small, weak ones frequently slip through the cracks.
However, those aren’t the ones that cause most fatalities…the stronger and more violent tornadoes do that, and we normally see their developing circulations well before they even touch down.