Update on the Minneapolis tornado

A Meteorologist’s worst nightmare? Did a tornado really hit south Minneapolis Wednesday afternoon around 2 pm? Based on the evidence (video captured by WeatherNation meteorologist Kristin Clark and Doppler radar imagery) it sure looks like a small EF0 or EF1 tornado formed over south Minneapolis and then dissipated as it swept north, towards the downtown skyline. Today NWS meteorologists will walk through damaged neighborhoods in South MCanon Falls, inneapolis, examining tree damage and how debris was carried through the air, trying to determine if it was straight-line, or tornadic. My hunch is that it was the latter.

What the heck happened? This was uncomfortably close to being “out of the blue”. The metro area was in a slight risk of severe storms from SPC, the Storm Prediction Center, but the general perception is that the local weather community was caught with its Doppler down. An upper-level disturbance, a counterclockwise-rotating swirl of unusually cold air 4-8 miles aloft sparked a widespread surge of rain, almost resembling an MCS, a meso-convective system, which tends to form at night, not during the day. Even though it was cool (upper 60s) there was enough instability, wind shear, and pure spin (vorticity) in the atmosphere to whip up brief, strong, “mesocyclones”, rotating thunderstorms capable of hail and tornadoes. The cell that formed over South Minneapolis developed VERY quickly, by the time warnings were formally issued and the sirens were sounding the threat (from the S. Minneapolis tornado) was probably long gone. It was a signal that the atmosphere was explosively/dangerously unstable, minutes later there was another touchdown near Cottage Grove, then later more tornadoes near Canon Falls, Mankato and North Branch. In all there may have been as many as 4-5 separate tornado touch downs on Wednesday

What the…? The Minneapolis tornado is making a lot of people very, very uncomfortable. It’s one thing if a tornado forms over fields with little/no warning, but within 1 mile of the MSP International Airport and 1-2 miles from downtown Minneapolis? That’s an entirely different scenario, the definition of an “OH CRAP” moment. No watches or warnings were in effect at the time of the apparent touchdown. To the best of my knowledge no local TV station was on the air warning of dangerous conditions bearing down on the Minneapolis skyline. Worst case? No, the IDS would not have tipped over. But outer glass walls could have been stripped, shattered – raining deadly debris on pedestrians below, severing the Skyway system, turning cars (and buses) on the Nicollet Mall into projectiles. A few years ago a study focused on Chicago, what might happen if a major, F3-F5 tornado struck during rush hour. The projections sounded like something out of a horror movie: 3,000 to 5,000 people dead, 20,000-50,000 locals injured, damage running into the BILLIONS of dollars. The report shook a lot of people up, myself included. A major tornado hitting a major city, especially at rush hour, with hundreds of thousands of commuters trapped in their cars, would be a catastrophe that would make Hurricane Katrina look like a proverbial walk in the park…

Major Urban Tornadoes. A recent study in the Dallas – Fort Worth area predicted that a major (EF3-EF5) tornado, hitting during rush hour, could claim thousands of lives, injuries running into the tens of thousands with a damage toll topping 2-3 billion. The report echoed a similar study focusing on Chicago, underscoring two things: a). in spite of a handful of tornadoes hitting downtowns in recent years we’ve been relatively lucky, and b). a worst-case, long-lasting, violent tornado would leave behind a trail of damage and death that could dwarf the aftermath of a major hurricane.

Thumbprint of a Tornado. Doppler radar captured by WeatherNation at www.weathernation.net. The spectacular video of the EF0 or EF1 tornado that hit south Minneapolis around 2 pm (no watches or warnings at the time) corresponded with this SRV, Storm Relative Velocity image from the Twin Cities, MPX Doppler. Note the vivid “couplet” just east of St. Louis Park, over south Minneapolis. The bright green is air moving toward the radar site (in Chanhassen), while the bright red air is moving away from the site, suggesting very strong rotation in this particular T-storm cell. The Doppler signature is a strong hint that this was, in fact, a small tornado, and not straight-line winds.



Doppler Evidence of a Tornado. Close-up of the SRV Doppler display, showing a developing tornado over south Minneapolis around 2 pm Wednesday afternoon. Check on the complete weather video at Conservation Minnesota to see the tornado that hit south Minneapolis.


By now you may have clicked on the video at Conservation Minnesota (www.mnweathercenter.org) and seen the fairly spectacular footage taken by WeatherNation meteorologist Kristin Clark this afternoon around 2 pm. She was on her Uptown balcony, with a sweeping view of downtown Minneapolis, with her parents, Tom and Noreen Clark (who I went to college with). Tom is a dear friend, the best man at my wedding, and a phenomenal TV meteorologist up in the Twin Cities of northeastern PA, Wilkes/Barre – Scranton. So they’re standing outside, admiring the view, no watches, no warnings, no sirens.

WeatherNation meteorologist Kristin Clark, who captured the tornado that formed over South Minneapolis around 2 pm Wednesday afternoon. The video can be seen at mnweathercenter.org.

Suddenly skies brighten a bit, their eyes focus on a dark, lowering cloud. What the…? It sure looks like a wall cloud, but how could that be? No tornado watches, no warnings…no way! Suddenly, with camera rolling, Kristin, Tom and Noreen are witnessing debris being thrown up into the air, the EF0 or EF1 tornado racing north towards downtown Minneapolis! My friend, Doug Williams, who works as a patent litigator at Fullbright Partners reported seeing flying debris from his high-rise office building around 2:30! What the tornado sucked up over S. Minneapolis it dropped right on the downtown.

What does this prove? It’s good to be lucky, and Kristin was in the right place at the right time. In her words “I’m no longer a tornado virgin.” Amen to that. It also underscores the fact that tornadoes can hit major cities. Just because you live in a metropolitan area does not mean you’re immune from a tornado risk.

Today’s freak-downtown-tornado also underscores the fact that Doppler radar isn’t perfect. It works best on the big tornadoes. Many times the small twisters, the EF0s and EF1s will get “lost in the sauce”, it’s very difficult catching every tornado of this size in advance. The bottom line: there’s still no substitute for common sense. Even if the sirens aren’t sounding, if you see clouds rotating, lowering to the ground, if you’re witnessing debris being tossed up into the air, do the right thing and head for safety!

In Kristin’s defense, she’s a smart gal: she could see – instantly – the tornado was moving away from her, racing north toward the downtown skyline at close to 30 mph. As much as we all liked watching her video, nothing is worth putting your life at risk, no more how dramatic the visuals. I’ll have more on today’s crazy tornado touchdown later this evening (there were other touchdowns near Cottage Grove – so far damage appears to be fairly light, but we don’t have all the information just yet).

Comments (1)

  1. Submitted by David Koski on 08/20/2009 - 12:51 am.

    I am not a meteorologist in any way, but I am having a hard time believing that the corridor of damage from approx. 48th st south all the way to downtown was caused by a tornado itself. My guess is that there were strong winds shearing from the southeast channeling up the Park and Portland north/south roadways feeding the formation of a tornado, which resulted in a funnel near downtown. From what I witnessed in the destruction the trees fell toward the west around 47th st and Park ave The rain could very well have loosened the root structure of large trees. From eyewitness reports that I have heard, there was no signature “freight train” noise of a tornado, but the wind was ferociously bending trees to the north. The time frame is not long enough from the distance in south minneapolis to downtown for it to be a tornado causing all of the damage.
    My best guess is that the tornado was forming very close to the ground.
    The heat energy amassed in the ground being released by the rainfall and supported from a colliding south easterly wind flow ran into the colder front somewhere around 94 and 35W near the Electric Fetus record shop. Thus creating a huge pressure drop and blowing out the windows. I speak of the heat mass since the ambient temperatures were not that high. The area had not really cooled down all that much yet, even with the recent lower temps.
    As good as Doppler radar is, this one was too quick and too low to the ground. WCCO initially reported that the tornado was to the north of Downtown, when I tuned in after hearing the sirens. One of ‘CCO’s own ex-employees had to call in and tell them about the tornado a few block south of them.

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