Expect the Unexpected - a severe weather safety case study

Special Update

Not all tornadoes are created equal, making some hard to predict. For example
this funnel cloud, along with two others, spun over the city of  Dalhart in
2004. Possibly a tropical funnel, it had little chance of becoming a tornado.
Had it touched down, its winds might have been in the EF-0 range.
The Amarillo NWS radar did not pick up any organized rotation in the
associated thunderstorm. The city sirens were sounded after the funnels
had been spotted by local law enforcement.  

If tornado alley has a bull's eye - it's central Oklahoma. The city of Moore, OK was surprised by a tornado towards the end of March, with all the drama caught on live TV. It was a weak tornado and no one was killed. Still, it provided an excellent case study in the need to take every warning serious and to expect the unexpected when severe weather comes to town.

The National Weather Service office in Norman saw the storm coming and issued a severe thunderstorm warning. The office sent out alerts over Twitter: "Storms west of OKC producing 60-70 mph winds. These winds will cause damage and produce power flashes." "Very damaging winds moving into SW OKC. Move away from windows. Expect wind damage and power outages!"

However, no tornadoes were expected in that area of the state - the atmospheric ingredients were not right. Still, Oklahoma understands severe weather. At least two of the Oklahoma City TV stations had their helicopters up, broadcasting live video of the approaching storm. Mike Morgan, on KFOR, noted some rotation on the station's radar. He switched to a view from the helicopter, spotted rotation in the cloud base and then, BAM! power flashes were seen on the ground.

A power flash is a bright, visible arc of electricity caused by power lines shorting out. It does not take a tornado to cause power flashes - strong straight-line winds rushing out of a thunderstorm can do it. However, rotating swirls of dirt could be seen on the ground, and Morgan called it a tornado.

The NWS office initially did not see it that way. According to the Norman office Twitter feed, tornado sirens were sounding at Tinker Air Force base, but they were insisting that damage was being done by straight line winds.

After a couple of minutes, the tornado's swirl could be seen on radar, and an official tornado warning was issued by the NWS.  It came six minutes after the tornado had developed.

Keep in mind, this was a not a classic supercell type tornado - the kind you can seen on radar 20 minutes out. This was a hard-to-predict, weak tornado embedded in the storm's gust front. The NWS was operating within the same warning guidelines they had used successfully year after year. Being the only agency in the U.S. that can issue a tornado warning, the NWS was not going to cry "tornado" unless they were reasonably sure it was.

Either way, both the NWS and the Oklahoma TV stations were after the same thing - keeping people safe. The NWS did so by issuing a severe thunderstorm warning due to the damaging straight-line winds. Mike Morgan spotted the tornado a few minutes before the NWS did and did not hold back telling his viewers what he thought it was.

And that is the nature of severe weather - it can, and does, surprise people. That is why every warning should be taken seriously. We might have a tendency to think a severe thunderstorm warning is not as bad as a tornado warning and just brush it off. But a severe thunderstorm, as was proven in Moore, can produce a tornado anytime it wants to. And even if a tornado never develops, strong winds created by the storm can still topple trees, as one did right here in Dalhart last year.

In short, not every instance of damaging weather can be foreseen. It is up to each one of us individually to keep an eye on the sky when storms are on the horizon, and use common sense. If something doesn't look right, or feel right, trust your instincts and take shelter until the storm passes.