I'm not sure what to say on this day of national tragedy. The damage from the Moore, Okla., tornado of May 20, 2013, is incredible. Our thoughts go out to the victims and their families. As meteorologists, what can we add? The tragedy probably couldn't be avoided, and if you're thinking it could have, stop. The best I can do is to provide some incredible radar animations of this record storm.
The first two images are GIF animations (click to animate), for your Google+ or Tumblr pleasure; feel free to share:
In the reflectivity image, the circular purple area shows the intense, large targets in the radar beam that form the "debris ball" (more information below). In the velocity image, you can track the tornado via the intersection of bright red and green (high winds).
How did we know for sure that the "debris ball" was present in the reflectivity image? A couple of years ago, we wouldn't have known for sure, but now there are different radar products that you can help us confirm a debris ball. First, a 3-D slice of the radar shows that the high reflectivity values are short - only extending up around 1,000 feet or so, while the intense core of the storm (similar reflectivity values) goes up to beyond 20,000 feet (which was the limit of the radar beam at this distance).
Next, we can also check the Hydrometeor Classification image from the Dual-Pol radar, which shows "unknown" (purple) in the area of the debris (red is hail, green is rain). This is a chilling classification by the radar, saying it doesn't understand what it's seeing: It's not rain, hail, or even biological targets (birds or insects). That's because it's dirt, buildings, cars and other debris.
Here are some additional radar loops. The first one features the reflectivity and velocity from the Oklahoma NEXRAD radar (as above) but starts out with a reflectivity loop from the TDWR (Terminal Doppler Weather Radar) at the airport, which is higher resolution.
And finally, a general regional look at all of the storms, including pressure, radar, warnings and local storm reports, with two zoom levels.
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