Use of LMA data “tips the scales” toward a warning

In the late evening of April 24, a strong storm was approaching Marion County in southeast Tennessee. I evaluated the storm to be just below severe levels. In the 4-panel image below, the LMA source density is in the lower left panel. 5 minute lightning and Hail Index are also in that panel. The POSH on this storm at this time was 40%, and source density values were around 80.

A 4-panel display of radar data from KHTX that incorporates LMA source density

At this point, I was on the fence about issuing a warning for Marion County, but leaning against it. Then the next LMA image came in:

LMA source density in the lower left panel showed a big jump from the previous image

Source density values jumped up over 200. Other radar products did not indicate significant intensification – other than the POSH rising to 60%, just about everything else stayed the same. But based on the big jump in source density values and the slight jump in POSH (and the favorable storm environment), I decided to issue a SVR.

The storm produced damaging winds near Jasper around 0410Z (1110 am CDT). The jump in LMA source density values gave about a 20 minute lead time.

As shown in this example, the LMA source density product can be useful along side other radar products and help “tip the scales” on a storm that may be borderline severe.

Doug Schneider

WFO MRX

2 thoughts on “Use of LMA data “tips the scales” toward a warning

  1. Doug —
    Thanks for this post. This is another great example of how the LMA data can provide utility and supplement radar data!

  2. This would be great to see the evolution of the mid levels of the storm added to the post if they are still available. It appears from the one frame at 3:51z that it may be trying to split.

    Great post.

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