Saturday, April 16, 2011

More on Tushka, OK Tornado of 4-14-11

The NWS in Norman is finalizing its survey of the tornado that struck the Tushka area in southeast Oklahoma on Thursday evening.  Based on the survey results thus far, they have assigned an EF-3 intensity rating to the tornado.  Tragically, 2 people lost their lives as a result of this tornado.

Several impressive videos of this massive, wedge tornado are coming forth on YouTube and other media.  Below are a couple that have allowed us to embed the video into this post:

This video has excellent images of the multi-vortex structure of the tornado:

Below are some images of the damage from the Tushka area:

In a "post-storm" post like this, I typically like to show detailed images of what the rotating storm looked like on radar.  Unfortunately, Tushka (as well as most of this portion of southeast Oklahoma) lies within an area that I like to call "radar no-mans land".  While there are 5 radars that cover this region (Oklahoma City, Tulsa, Ft. Smith, Shreveport and Ft. Worth), they are all at a distance from the area such that the radar beam is usually slicing through higher levels of the storms, rather than the lower several thousand feet (where we get the best picture of what the low-level structure looks like).

This happens because as the earth curves, the radar beam (initially shooting into the lower levels of a storm closer to the radar site), shoots into increasingly higher levels of a storm further away from the radar site.  See the illustration below to see what I'm talking about:

The Oklahoma City area radar is the closest to Tushka (82 miles away).  At that distance, the lowest-level radar scan is slicing through the storm at an elevation of about 12,000 feet above ground level.  Ideally, we'd like to see the lower 6,000 feet to get the best idea as to the low-level rotational structure of a severe storm.

This is why, even in today's highly technological era, ground truth severe weather reports from trained storm spotters in threatened areas are still a critical part of the warning process.

With that said, this storm was a very well organized supercell, and even though the radar was examining a higher level of the storm than we'd normally like to see, the rotational signatures were still very impressive indeed (particularly on the reflectivity side).

In each of the radar images below, the left half of the image shows the reflectivity display (rain, hail, etc.) from the Oklahoma City radar, while the right half of the image shows the velocity (wind speed & direction) display.  Times are noted below each image (click to enlarge):

00:16 GMT (7:16 PM CDT)

00:20 GMT (7:20 PM CDT)

00:24 GMT (7:24 PM CDT)

00:29 GMT (7:29 PM CDT)

00:38 GMT (7:38 PM CDT)

00:43 GMT (7:43 PM CDT)

Remember, when looking at the velocity images, green shows wind blowing toward the radar, while red shows wind blowing away from the radar.  In this particular case, the radar site is located off of the upper left corner of the images.

I'll post a detailed ground-level track map once the survey is complete.

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