Thursday, March 22, 2012

The Tornado Chronicles: Devine, Natalia, Lytle, Southwest San Antonio Tornado of 3-19-12...

A tornadic supercell produced three tornadoes just to the Southwest of the city of San Antonio, TX on Monday evening, March 19, 2012.

Below are some still photos of the tornado taken by citizens in and near Devine:

There is a home video of the tornado, reportedly when it was near Devine, at this link on KSAT-12's site.  Note the power flashes as transformers explode at several points during the video - always a sure sign of a tornado at night (even if you can't see the tornado).

Here is another video near Devine taken by Roxanne Chevera:

According to the Medina County Sheriff, 20-25 homes were heavily damaged in Devine, with at least 5 injuries reported.  A semi was reportedly overturned on I-35 near mile marker 127, between Lytle and Natalia.

The "BaseHunters" chase team captured this video along I-35 to the Northeast of where the overturned semi report came in.  It is a good illustration of why we always talk about the dangers of a nighttime tornado.  Throughout most of the video you really can't see anything (except briefly during lightning flashes).  If you look closely at about 1 minute and 40 seconds in they slow the frames down and you can clearly see the tornado, as well as power flashes which are always a sure sign of a night time tornado:

The photos below were taken by KSAT-12's helicopter as it flew over the Devine area earlier this morning.  I definitely see EF-2 damage, and depending on the construction type of some of the structures, possibly EF-3 damage:

Further Northeast toward San Antonio, we have reports of damage along both Ted Williams Road and Ladd Road in southwest Bexar County.  This is about 9 miles Southwest of Loop 410, to the North of I-35.  

The National Weather Service (NWS) conducted a storm survey which revealed 3 tornado tracks.  The track map below is based on the starting and ending latitude/longitude points of each track, and then used survey, photos and radar data to construct the general shape of the paths (click to enlarge):

The NWS survey rated the tornadoes as follows:  "Devine" at EF-2 intensity, "Natalia" at EF-1 intensity, and "Southwest Bexar County" at EF-2 intensity:

The following image was put together by the blog disastermapping and shows the path of the radar indicated tornado circulation centers associated with each tornado (the blue-white dots on the image):

As you can see, according to the radar, each tornado developed along or North of I-35 and moved in a general North-Northwest curved fashion (as indicated on the track maps above) before diminishing and reforming back to the Northeast.  

Devine is located in Medina County.  Going back as far as 1950, I can only find one instance of an F-3 tornado, which took place on April 29, 1975.  An F-2 tornado last took place in Medina County on April 7, 2002.

As far as Bexar County (home of San Antonio) is concerned, the last time an F-3 intensity tornado took place was on November 22, 1961.  An F-2 tornado most recently took place oddly enough on the same day, March 19th, back in 2002.  Even more interesting for weather trivia buffs... the March 19, 2002 tornado took place between Lytle and Van Ormy, along I-35 very near where last night's tornado tracked!

For details on the difference between the "old" F-scale and the current EF tornado intensity scale, see this post.

If you have an interest in this tornado, please bookmark this post and check back throughout the day for additional information as it becomes available...

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1 comment:

Mark said...

Nice pics.... I was tracking this exact storm!!!