Friday, August 7, 2015

Trouble With Unwarned Storm In Alabama, And Ignoring A Warned Storm In New Hampshire

Inside a Troy, Alabama Walmart after a suspected
tornado heavily damaged the store.  
UPDATE: The National Weather Service in Birmingham confirms that it WAS a tornado that trashed that Walmart.

In their defense, as noted in an update in Dennis Mersereau's Vane blog, the rotation in this storm as depicted by radar last night appeared to be fairly weak.

These weakly rotating storms rarely end up producing a tornado, so the National Weather Service usually doesn't issue tornado warnings for such storms.

Weakly rotating storms often pass over Alabama, and the National Weather Service is reluctant to issue tornado warnings for storms that are highly unlikely to actually produce a twister.

If you issue too many warnings with nothing materializing, you get accused of crying "Wolf!" too many times, which would lead people to ignore warnings for more dangerous storms in the future.

In rare cases, and this looks like it might be one of those weird cases, the rotation appeared weak, but the tornado was there, and fairly strong.

To my relatively untrained eye, the rotation signals looked pretty obvious. But obvious does not mean strong, and obviously doesn't always mean a tornado is there, especially if the rotation isn't violently strong.

It all goes to prove that we still have quite a bit more to learn about tornadoes and other severe weather hazards.

I'd bet my next paycheck that a lot of meteorologists will be studying this event in detail to see what could be learned from this situation. It'll also be a topic of seminars and conversations at future meteorological conferences.


Despite a National Weather Service apparatus that can usually detect potential tornadoes, one apparently hit without warning last night in Troy, Alabama.

The storms hit a Walmart and a sports equipment store while people were inside, caving in roofs. Miraculously, nobody died, but at least five people were hurt.

Dennis Mersereau, who writes Gawker's The Vane weather blog, broke some disturbing news about the lack of warnings for this tornado.

Sometimes, tornadoes aren't easily visible in radar and wind velocity detecting equipment, and so warnings don't get issued.

In this case, Mersereau shows radar images that had can't miss signs of a tornado associated with its parent thunderstorm  at least as early as 10:24 p.m. last night. A tornado warning was not issued until 10:39 p.m., after the stores had been hit.

Forecasters sometimes miss tornadoes because there's no clear sign of them on radar. But this one had a pronounced hook echo, and other images on radar called base velocity showed a very tight rotation, indicating a tornado.
Overall, the area where the tornado hit in Alabama was not considered at high risk of a tornado on Thursday, but obviously, one likely did hit. Goes to show these things can happen even when conditions are only marginally ripe for severe weather.

Mersereau said he has reached out to the National Weather Service office in Birmingham, Alabama, which is responsible for weather warnings in that area, to get an explanation.
Sporting goods store heavily damaged by
 a likely tornado in Troy, Alabama last night. 

As Mersereau notes, the Birmingham NWS office is in tornado country and usually does an excellent job with tornado warnings.

I don't know if there really was a slip up last night with the Troy, Alabama tornado warning. It'll be interesting to see what Mersereau finds out from the National Weather Service.

However, nobody's perfect. There could have been a mistake, or somebody might have been asleep at the switch. We'll find out.

If Mersereau is right with the timing of the events, the National Weather Service in Birmingham has some explaining to do. Not because heads should roll, but because this could be a learning opportunity for monitoring, forecasting and warning people during future storms.

Meanwhile, we have news of the risk of NOT responding to weather warnings. The National Weather Service in Gray, Maine on Monday issued a severe thunderstorm warning for the Lancaster, New Hampshire area, where a local fair was going on alerting people to oncoming wind gusts of at least 60 mph.

That's enough to rip a circus tent up.

The warning was issued about 20 minutes before a circus tent collapsed, killing a father and young daughter and injuring several others.

The warning was issued just before the start of the evening's show. Also, forecasters had been saying since at least the day before the storm that there was the possibility of severe weather. 

Plus, severe weather had been reported in neighboring Vermont and further south in New Hampshire earlier that afternoon. That activity was heading north, so it would have been worth it to watch things, with or without official warnings from the National Weather Service.

It's the responsibility of an outdoor venue operator to monitor weather and evacuate people to sturdier shelters when storm warnings are issued. It's still unclear why this circus did not postpone the show and move people to stronger buildings when the warning was issued.

I don't even know yet if somebody was monitoring the National Weather Service for warnings and updates.

It is a bummer when an outdoor event is canceled due to the threat of severe weather, but that disappointment pales in comparison to lives lost.

I've seen how this type of thing is done right. On a sunny Saturday in early June, I was at the annual Rockin' Rib Fest outdoor festival in Yankton, South Dakota.

While I was there, a tornado watch was issued for the area. A watch is a step down from a warning. A watch means a tornado is possible, a warning means a tornado is imminent or at least very likely.

The Rib Fest organizers announced the tornado watch to the crowd less than 10 minutes after it had been issued.   The announcer just told people to keep an eye to the sky and listen for later updates, but the festival continued, which was proper, since there was no severe weather nearby at the time.

Ultimately, there was no tornado that day in or near Yankton, but a lot of lightning developed later that evening. The lightning prompted organizers to shut the whole event down and everyone was urged to leave and get out of harms way as thunderstorms rattled over Yankton for hours that Saturday night. 

Organizers surely lost a lot of money in cancelling the annual event. But imagine how horrible it would have been if lightning or strong winds hit the event with hundreds or thousands of people there.

To me, better safe than sorry. 

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