The Illinois-Indiana-Ohio Tornado Outbreak – 5 June 2010

Eight years ago today, a large tornado outbreak affected portions of Iowa, Illinois, Indiana, Michigan, Ohio, and Pennsylvania.


Tornado near Yates City, Illinois. Photo credit: Jarrod Cook

My memories of that day are foggy.  I do remember the day, though, as it happened during VORTEX-2, the massive tornado field project.  That day, as with many days in 2010, we chose poorly.  If I remember correctly, we decided to play Nebraska the day before, which put us out of position for eastern Iowa / Illinois.  Thus, some time around midday on June 5th, we decided to call the day “down.”  I distinctly remember eating an Omaha steakhouse that evening with Justin Walker and Herb Stein.  When images of the Yates City, Illinois tornado appeared, I sank my head in misery.

It had been a tough season.  We had already screwed up May 22nd, the day of the infamous Bowdle, South Dakota EF4.   We called that day “down,” too.  (I must sheepishly admit that I was the stand-in Day 1 forecaster for that day.  So I probably share some  of the blame for that mistake.)  I don’t know why, but we picked some very bad times to sit out.  I think we also sat out Campo Day, too.  (Though, to be fair, that day was *much* less obvious.)  So when the June 5th outbreak happened, it was insult to injury, to say the least.

Interestingly, prior to the outbreak, June 5 did not seem like it would be a big day.  Many of the models, including the NAM, forecasted that a cold front would drive the moisture / potential instability far away from the stronger flow to the north.

About 24 hours before the outbreak, the modeled position of the front began to trend northward.  This raised confidence in the potential for tornadoes.  Thus, the Storm Prediction Center upgradedd from slight to moderate, with a 10% risk of tornadoes along the boundary.

Storms formed the morning of the 5th, along and north of the boundary.  However, the storms were not strong.  Thus, the cooling effects of the rain were outweighed by the strength of the return flow.  So the front stayed closer to the strong upper flow.

As with most big days involving boundaries, the air north of the boundary cooked under the late spring sun.


This resulted in warm surface temperatures north of the boundary.  With high-octane Gulf moisture in place, the surface component for explosive storm development was in place.


A sounding from central Illinois (ILX) at 00Z showed an strong-tornado-supporting environment.  Surface-based CAPE was near 3000 j/kg.  Deep-layer shear was above 50 kts.  And the all-important 0-1 km storm relative helicity was greater than 200 m**2/s**2.


Around 2300Z, powerful thunderstorms developed in eastern Iowa and northern Illinois.


By 0130Z, a full-fledged tornado outbreak was underway.


In all, 43 tornadoes struck that day.  I suppose that one could reasonably describe it as a “regional tornado outbreak.”


June 5, 2010 Tornado Outbreak. Source: Storm Prediction Center, SeverePlot

Granted, most of the tornadoes were on the weak end of significant.  But it was still a fairly impressive outbreak.

The most significant tornado struck the small town of Millbury, Ohio — just outside of Toledo.  The late-night tornado was not large: only 100 yards at its widest.  However, it was fierce, producing EF4 winds.  In all, five people were killed.

Midwest Storms

Damage in Millbury, Ohio. Copyright:


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Rare Fall Tornadoes Possible Tomorrow

The ingredients are coming together for a rare fall-season outbreak of severe weather weather in the Plains on Monday.  The primary driver for this threat is a powerful upper-level trough entering the Plains from the western U.S. The flow at 500 mb will range from 40 kts, to a blistering 90 kts at the center of the jet streak.


500 mb
6 pm, November 16th

Air will move down the Rocky Mountains, creating relatively low pressure east of the mountains.  As a result, a very strong pressure gradient will develop.  This will lead to the development of a powerful low-level jet, as can be seen in the NAM 850 mb forecast.


850 mb
6 pm, November 16th

The resulting strong southerly low-level winds will transport unseasonably high moisture northward toward the Plains.  Dewpoints will be rather high for November, with the 60 F dewpoint line far into the Texas Panhandle.

Surface - Valid: 00Z 17 November Source:

6 pm, November 16th

The colder temperatures high in the atmosphere and moist air at the surface will combine to produce substantial instability over the Southern Plains.


Surface Based CAPE
6 pm, November 16th

Though surface-based convective available potential energy (SBCAPE) values will be somewhat low, large values of shear should compensate.  Deep-layer shear (0-6 km) should be more-than-sufficient for the development of strong supercells. And the all-important low-level shear values should be nothing short of incredible.  According to the 4 km NAM, values will exceed 200 m2/s2 in most places.

0-1km Storm Relative Helicity Valid: 00Z 17 November Source: pivotal

NAM 4 km
0-1km Storm Relative Helicity
6 pm, November 16th

Generally speaking, tornadoes are possible when values exceed a 100 m2/s2.  So, with values well over 200 – and in some cases, over 400 – you get the idea that we could be in for a rather bumpy Monday evening.

The full effect can be quantified by the significant tornado parameter.  Values greater than 1 indicate the potential for tornadoes.  In this 4 km NAM forecast, local modifications of the storm environment result in values over 5!


NAM 4 km
Significant Tornado Parameter
6 pm, November 16th

Based on the aforementioned ingredients, the Storm Prediction Center has issued an enhanced risk for severe weather for most of the Southern Plains.


Day 2 Outlook
Storm Prediction Center
November 16th

As far as timing is concerned, most higher resolution models are calling for isolated development to begin between 3 and 6 pm.  The NAM 4 km (featured here) is producing a couple of robust-looking supercells over west Texas into western Oklahoma by 6 pm.


NAM 4 km
Simulated Reflectivity
6 pm, November 16th

These storms are forecast to move into western Oklahoma and western north Texas after dark. This forecast sounding in southwestern Oklahoma shows a deep moisture layer, significant CAPE, and extremely strong low-level shear.


NAM 4 km
Forecast Sounding
Near Gotebo, OK

Given the relatively cool surface temperatures and moist air, the cloud bases forecast to be a low 500 m.  So, no surprise: the forecast analogs favor tornadoes.

More importantly, the capping inversion will remain relatively weak throughout the evening.  So it is quite possible that storms will produce tornadoes after dark.  This reflectivity forecast gives the idea that small line segments may form, but semi-discrete storms could persist toward 9 pm.


NAM 4 km
Simulated Reflectivity
6 pm, November 16th

In summary, there is a good chance of significant severe weather across west Texas into western Oklahoma, with the threat of large hail, damaging hail, and tornadoes.  There is definitely no guarantee of an outbreak of tornadoes, but it would be good to start reviewing your tornado safety plan – especially if you live in western Oklahoma or west Texas.

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An Unforgettable Chase – The EF5 Moore Tornado (5/20/13)

Two years ago today, I observed an EF5 tornado ripping through Moore, Oklahoma.  Before the tornado, I had always wondered what it would have been like to see an F5 hit Moore (thinking of 5/3/99).  I never thought that I would actually find out.

That morning, I woke up late, in anticipation of a late start to my work day at the National Weather Center. Since it was a weekday, I wasn’t planning on chasing. Out of curiosity, though, I thought I would check out the forecast. While waiting for my computer to boot, I went outside to get a feel for the weather. It was sunny – but cool – and stratocumulus clouds were racing northward with the low-level jet. It just had the “feel” of a big day (most folks who have spent significant time in Tornado Alley know what I mean).

I went back inside to check out the forecast. After going through the usual parameter checking, I perused a few convection-allowing models (weather models that predict actual thunderstorms). An ominous forecast was projected: supercell thunderstorms would develop in central Oklahoma by mid-afternoon. I became increasingly concerned about the possibility of a significant tornado not far from Norman.

OUN WRF - May 20

8 hour forecast of updraft helicity and reflectivity from the OUN WRF on 5/20/13.

About an hour later, I arrived at work. Realizing that storms were already firing, I started to become antsy.  I checked the SPC mesoanalysis, and realized a very potent atmosphere was already taking shape. Dewpoints were close to 70 F, instability was extreme, and low-level shear was strong enough to promote strong tornadoes – long before the usual increase of strong winds near sunset.

I was able to get off work, but I started my chase a little late (around 2 pm).  I called a friend of mine to see if her chase group had left town yet. I was very relieved to find out that I had caught them in time (I didn’t want to chase alone). So I quickly met them on the southeast side of Norman, where we began our chase.  A major supercell had already developed near Duncan, Okahoma, so we took off on Highway 77 to go toward it.

Near Purcell, we learned that a storm near Newcastle had already become tornado-warned.  A quick check of radar showed a very poweful-looking supercell with a large hook echo.  We immediately decided to go north toward it. While were driving into Purcell, we heard a report of a tornado with this storm.  That was quick!  One of my chase partners pulled up the KWTV live feed on her phone and saw that a photogenic stovepipe tornado had formed.  By the time we entered I-35 north of Purcell, the tornado had already become a wedge (a period of about 3 minutes). We zoomed north as quickly as possible.  As we went along, the rock-hard flanking line becoming visible – some of the most powerful convection I’ve ever seen. In Norman, we scanned the sky to the northwest, looking for the tornado.  It was too hazy.

At Tecumseh Road, we exited I-35.  It was about 3:05 pm.  While crossing the bridge near the Healthplex, we caught our first glimpse of the tornado to the west-northwest. Though it was still hazy, we could easily make out the massive wedge against the pale orange sky behind it.  I couldn’t believe my eyes: it was happening again.  A violent tornado was moving into Moore.  To say it was “surreal” is a vast understatement.

We continued west until we arrived at Santa Fe, where we turned north.  Trees and houses obscured our view for a while, and during this stretch the funnel transitioned to a stovepipe.  Near the intersection of Indian Hills on Santa Fe, we saw the tornado again.  There, I was stunned to see the violence of the motion at the base of the funnel.  Other than the El Reno tornado of May 24, 2011, it was the most violent tornado I’d seen.  I began to pray incessantly as I realized it wasn’t going to stop before Moore.


Moore EF5 tornado as viewed from Indian Hills and 36th. 3:15 pm on 5/20/13

Fearing a right turn by the tornado, we turned onto Indian Hills – just south of due east from the tornado.  We stopped at a church parking lot along the road to film the tornado.  As the tornado drew closer, I began to see large chunks of debris encircling the tornado.  I looked above the funnel and saw shimmering pieces of metal – roughly 3 or 4 times taller than the funnel.  The updrafts in the tornado were incredibly powerful: at this time, the tornado moved a large water tank (10 tons empty) over a half mile and deposited it in someone’s backyard.


10-ton tank tossed 0.5 mi by the Moore tornado.

Around the same time, an unmistakable roar became audible.  I would liken it to the sound of a thousand waterfalls.  No straining was necessary to hear it, even from a distance of two miles.  I can’t convey the horror of realizing that people are probably dying right in front of you. The usual excitement of seeing a major tornado was nowhere to be found.  All I felt was anxiety and fear: this wasn’t happening to strangers, this was happening to my friends.  It was sickening.

The tornado became increasingly rain-wrapped as it approached I-35.  I thought, mistakenly, that the tornado was widening into a large wedge. The reality was that a combination of rain and debris created the illusion of a larger tornado.  Around that time, I remember looking north and seeing Andy Alligator’s / HeyDay with the dark mass behind them; it was such a strange contrast!

As we were crossing I-35 on Indian Hills, it was pure chaos. A traffic jam had developed south of the tornado on Telephone Road, and a cop was yelling at us to keep it moving. We continued east as we lost sight of the tornado, now wrapped in rain and hidden by buildings. About 5 minutes later, the tornado came out of the rain as a much-smaller stovepipe. Even though it was smaller, video that I saw later revealed it to be quite violent near the base. Just as we were driving north for a close approach on Sooner Road, the tornado began to rope out – and quite spectacularly. The funnel writhed chaotically for about 30 seconds, debris centrifuging outwards and falling downward.  Forty minutes after it began, the tornado dissipated.

We couldn’t believe what we had just seen. We listened to horrifying reports on the radio of complete devastation, somewhere near the Warren Theater. We realized that we had just seen a historical tornado, but there was no celebration in our vehicle. I guess the best way to describe it is “numbness.” We contemplated returning to Moore to help, but we realized our ignorance of how to help could put us in the way at best, or get us killed at worse (downed powerlines, glass shards, nails, etc.). So, we decided to chase on.

The remains of the Briarwood Elementary School.

The remains of the Briarwood Elementary School.

We saw another tornado near Pauls Valley. It was a 30-second multiple-vortex tornado. Normally, I would’ve been thrilled to see it. But I can honestly say that I’ve never been less enthused to see a tornado. It seemed as if the rest of the chase was simply out of obligation, because I didn’t want to regret it in the future. Mercifully, the rest of the event was lackluster, as storms lined out in southern Oklahoma. It is a day I will never forget.

Video of the chase.

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One Year Later: Reflections on the Loss of Tim, Paul, and Carl


It’s been a year.  In one way, that’s very easy to believe, because so much has happened.  Some of it has been negative, but most of it has been positive.  I’ve made new friendships and deepened others.  The numbing fog of loss has given way to hopeful – but sober – clarity.  Yet, in many ways, there is still a certain unreality about what happened.

Did we really lose Tim, Paul, and Carl?  It all feels a bit illusory still.  I replay the events over and over in my mind.  But, for some reason, it becomes less real – not more.  I know the story through and through, but full acceptance remains elusive.  I suppose that’s true for almost any traumatic loss.

And, I’m certain there are other impacts that I can’t quite see, because I’m in the thick of them.  I don’t chase storms the same way anymore.  I don’t think about tornado victims the same way anymore.  I don’t think of friendship the same way anymore.  So much has changed.  And yet, I feel that the changing isn’t near done.

But I think that this is good.  The smelling salts of tragedy are not pleasant, but they can be beneficial.  Feeling the impact of extreme loss can afford the sobriety that causes one to treasure the gifts that remain.  I know, for my part, that I cherish my relationships with my family and friends more than ever.  It’s a direct result of experiencing the loss of Tim, Paul, and Carl.  And while I would – as my friend Marc Austin puts it – trade all the tornadoes I’ve seen if it would bring them back, I know that my life is all the better because of what happened.

And yet, I still miss them.  I can still hear Carl trying to talk me into chasing the next setup, his cheery voice almost convincing me to join him.  I can still hear Paul talking hopefully about his ambition to become a movie maker, and me not doubting for a minute that he would succeed.  And I can still hear Tim talking about tornadoes of antiquity, and feeling that I had found a kindred spirit.  I wish I’d had more time with them.  But I thank God for the time I was able to spend with them.

“There is nothing that can replace the absence of someone dear to us, and one should not even attempt to do so. One must simply hold out and endure it. At first that sounds very hard, but at the same time it is also a great comfort. For to the extent the emptiness truly remains unfilled one remains connected to the other person through it. It is wrong to say that God fills the emptiness. God in no way fills it but much more leaves it precisely unfilled and thus helps us preserve — even in pain — the authentic relationship. Furthermore, the more beautiful and full the remembrances, the more difficult the separation. But gratitude transforms the torment of memory into silent joy. One bears what was lovely in the past not as a thorn but as a precious gift deep within, a hidden treasure of which one can always be certain.” –Dietrich Bonhoeffer

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Clarification of El Reno Tornado Width Claim

It has come to my attention that the tornado width ascribed to the El Reno tornado in my previous post is not quite accurate.  On the topic, Josh Wurman writes,

“That is a ridiculous interpretation, out of context, of the observation that the width of 30 m/s winds at >100 m AGL sometimes extended for about 7 km and that the equivalent 50 m/s width was as wide as 5 km.  How those correlate to expected surface damage is unknown.  The paper has a long footnote saying that using these definitions as ‘width’ is very subjective.  The diameter of the large circulation was about 2 km, very large, but similar to other Multiple Vortex Mesocyclones (MVMC) that we’ve documented before.”

I believe the confusion lies in the definitions contained within the conference paper.  In the paper, Wurman seems to equate the multiple-vortex mesocyclone (MVMC) with the tornado itself, noting that an interior sub-vortex was “nearly concentric with the larger tornado / MVMC”  (Wurman et al. 2013, AMS Radar Conference).  The slash would seem to indicate the interchangeability of the terms “tornado” and “MVMC”.  However, this is not the case.  In an early online release of the BAMS article of this work, it is clear that the 7 km (4.3 mi) width is ascribed to the parent circulation, not the tornado.  My previous post has been edited to reflect this understanding.

Regardless, the 2.6 mile width will remain in the record books, according to the National Weather Service.

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10 Amazing Facts about the El Reno Tornado!

The El Reno tornado, shortly after development. Photo credit: Gabe Garfield

Video capture of the El Reno tornado
 (Gabe Garfield)

The weather radar conference is ongoing in Colorado this week, and one of the conference papers features some eye-popping statistics regarding the 31 May El Reno tornado.  This paper, authored by Josh Wurman and others, is titled “Preliminary Results from the ROTATE-2013 Season”.  Now,  for the facts …

  • Near Highway 81, the El Reno tornado achieved a peak forward motion of 55 mph!  This is comparable to the highest translational velocities of tornadoes ever observed by the Doppler on Wheels (DOWs).
  • After the tornado crossed Highway 81, the sub-vortices (smaller tornadoes) within the larger circulation grew to mammoth proportions.  The largest were bigger than the size of 3 football fields combined!  (Most parent tornadoes do not reach this size!)
  • As the tornado approached Highway 81, small vortices developed on the northwest side of the circulation and “fed” the circulation.  Similar vortex behavior was noted with the gigantic Seward, Kansas tornado (23 May 08).
  • The tornado displayed vortices on multiple scales, similar to matryoshka dolls.  This “tornado within a tornado” behavior was noted shortly before the tornado crossed 81.   At that time, the tornado had two prominent vortices: an inner vortex, about 150 yards in width; and an outer vortex, about 1.25 miles in diameter.  Wurman notes this behavior in other large tornadoes, including the Kellerville, Texas (8 June 95) and Harper, Kansas (12 May 04) tornadoes.
  • One of the most intense sub-vortices during the El Reno tornado translated at an incredible 180 mph!  Curiously, this sub-vortex was also stationary at times during its 2 minute life-span.
  • At 6:26 p.m., the DOWs measured a 255 mph gust in a sub-vortex just south of Interstate 40.  This exceeds the EF5 threshold by over 50 mph.
  • Given the fast translation of this sub-vortex, a stationary observer would have only experienced these maximum winds for 0.5 seconds.  Talk about acceleration!
  • Applying a theoretical model (Rankine vortex) to the tornado yields velocities between 290 and 330 mph!  Of course, this assumes the theory is a good model of the real atmosphere (among other caveats) – but still, it’s very impressive.
  • Officially listed at 2.6 miles in diameter, the El Reno tornado is the largest tornado on record.  But it might also be the largest tornado ever documented.  Using the 30 m/s wind threshold (and excluding the rear-flank downdraft winds), the tornado was an unbelievable 4.3 miles wide!!  (Even using a 50 m/s threshold yields a 3.1 mile wide tornado … unbelievable!)  For comparison, this is larger than the Mulhall tornado (3 May 99), which was the previous standard-bearer for behemoth tornadoes (2.8 miles in diameter using the 30 m/s threshold).

    EDIT: The 4.3 mile width in the paper refers to the parent circulation of the tornado, not necessarily the tornado itself.  It should also be noted that the 4.3 mile width was > 300 feet above ground level, not necessarily corresponding to the size of the tornado.

  • In addition to the gigantic cyclonic tornado, the El Reno storm simultaneously produced a strong anti-cyclonic tornado.  This tornado featured powerful sub-vortices (potentially, the first ever documented) with winds peaking around 145 mph!

(Here is my video of the El Reno tornado.)

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