Debris at 30,000 Feet?

Image from NWS Tulsa

Image from NWS Tulsa

Have you ever wondered what the significance of dual-pol radar is and how something like having live ARMOR dual-pol radar can make a difference? One of the “moments” that dual-pol radar creates is the Correlation Coefficient. This one is really useful in determining (to some degree) precipitation type and consistency and detecting non-meteorological things like bugs, dust, or even debris kicked up by a tornado.

Back on April 27th when the EF-5 tornado struck the Wrangler plant in Hackleburg, it carried blue jeans to Soddy-Daisy, Tennessee. How in the world did they get there? Dual-pol’s CC value (correlation coefficient) helps explain how that probably happened – out the top of the thunderstorm and into the air roughly 30,000 feet above the surface.

This image from the NWS Tulsa shows how the CC value is indicating that there is something that might be debris being thrown east of the Moore and Shawnee, Oklahoma tornadoes – in the anvil miles ahead of the thunderstorm:

Image from NWS Tulsa

Image from NWS Tulsa

Correlation Coefficient is a product that measures the correlation of the horizontal and vertical backscatter of power in the radar’s sampling. That’s a big way of saying since dual-pol radar sends out a pulse oriented in the vertical and in the horizontal, we can look at how those different pulses behave to see if precipitation is uniform (like ALL rain or snow) or if it is variable (like debris or a wintry mix).

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If you’re interested in learning more about this, I suggest you look at the online training from the Warning Decision Training Branch of NOAA.

-Jason
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