28 April 2010

Albertville Was Luckier Than Most- Here is why.

Posted by Dan Satterfield

Dan's photo.

The EF 3 tornado that hit Albertville developed very rapidly. It first touched down just west of the city. It was on the ground for about 30 minutes and lifted near Geraldine in Dekalb County. We were able to give nearly 30 minutes warning for the folks in Geraldine. Albertville had 7 to 8 minutes.

That may not sound like much, but for a town at the beginning of the track, that is actually very good. Especially in this case.

Look at the radar images.

Velocity data shows a weak and ragged circulation, at 10:07 PM, as the storm enters Marshall County.

At 10:07 PM the velocity data showed a ragged circulation in the storm as it entered Marshall County Alabama. It takes the radar about 6 minutes to do a complete scan at several elevations. This is called a volume scan.

One volume scan later at 10:14 PM a strong circulation has developed. The NWS office in Huntsville issues a Tornado Warning. We had been keeping a weary eye on this cell.  I was doing the 10 PM  weather and we immediately urged the folks in Albertville to “take cover right now!”.

One volume scan of the radar later- a strong circulation is present. Tornado Warning being issued.

At 10:22 pm the radar data shows a very intense circulation with winds over 100 knots. The circulation is very near Albertville.

10:21 PM: An intense rotation is near Albertville. The tornado struck at 10:22 PM. (Pink is high winds away from the radar, and cyan is strong wind toward the radar. Radar located at top of image.

I talked with an Albertville city councilman who is also a state trooper.  He was off duty, but looked at his watch as he saw the tornado lift a giant tree out of the ground.

It was 10:22pm.

Albertville had around 7-8 minutes of warning.

Much more than most cities right at the beginning of a track will usually get.

This is why you should have a NOAA weather radio. Even if you have the TV on, you may be in another room or preoccupied. That warning siren might give you enough time to get to shelter. If you are very close to where the tornado is developing, you may only have seconds.

When it comes to tornado warnings, 7 minutes is a lifetime to a severe weather nowcaster.