24 May 2008 Archived Lightning Case

With no lightning in any of our total lightning domains during operations Monday and Tuesday, the forecasters focused on the archived case from 24 May 2008 near Enid, Oklahoma. This case has served as a good introduction to the pseudo-GLM flash extent density product ahead of the real-time operations that have been taking place Wednesday afternoon. This event was interesting to go through, with a northern cell in Garfield County and a later, southern cell in Kingfisher County. The scenario starts with the northern cell already active. Both cells showed strong lightning jumps ahead of intensification.

For the northern cell, the jump preceded the formation of a strong rotation couplet. However, storm reports did not indicate an observed tornado or severe weather. I had remarked after the event that this was one of the stronger jumps I had seen without a severe weather report. Most of the forecasters warned on this storm due to the radar velocity signature, but the lightning jump helped add confidence. Potentially, severe weather occurred, but due to the location of the storm nothing was observed.

The southern cell demonstrated the utility of total lightning for both lightning safety and severe weather operations. As the southern cell began to develop, the pseudo-GLM indicated lightning activity 5 minutes before the first cloud-to-ground strike. Initially the pseudo-GLM was showing a flash density of 6 flashes at 1902 UTC. This gradually increased for the next 8 minutes and then demonstrated a rapid jump to 86 flashes by 1919 UTC. This occurred 8 minutes ahead of the first reported tornado just west of Lacey, Oklahoma at 1927 UTC. During the post analysis, this lead time was significant for the event as the radar velocity signature was weak at 1921 and was just showing signs of a couplet at 1926 UTC. The reflectivity was showing some signs of a hook at 1921.

I feel the discussions from going through this event with four forecasters were the best results. I will follow-up with this in a subsequent post.