This week started with two very active days within the OUN CWA which allowed EWP forecasters to incorporate pseudo-GLM products into their warning operations.  Despite the dense radar coverage, forecasters used the total lightning products and provided some interesting insights.

Day One – Monday 23 May

Two storms developed in Northwest Oklahoma and exhibited very different lightning and radar signatures.  The northern storm formed in Major County, exhibited very large IC flash rates, and produced large hail.  Conversely, the flash densities were much smaller in the southern storm which produced a brief tornado.  This observation illustrated the variability between two storms that occurred in a similar environment and emphasizes the importance of continued research on the relationships between lightning and radar within individual storms.

The greatest pseudo-GLM densities (> 30 flashes min^{-1}) accompanied a large storm cluster which followed the merger of two strong storms.  The 3D-Var products indicated a strong updraft throughout the length of this storm cluster which helps explain the high flash rates.

Day Two – Tuesday 24 May

The high risk forecast and model-derived products all indicated a very active day was in store.  The CI products identified the initial convection 15-20 minutes prior to the first pseudo-GLM signatures.  Flash rates increased rapidly in the earliest convection, and the first tornadic storm occurred as two isolated storms merged near Weatherford, OK.  Flash rates spiked as the two storms merged, coincident with an increase in mid-level rotation.  These combined observations increased forecaster confidence as they issued the first tornado warning of the day.

The EWP forecasters observed that the greatest pseudo-GLM flash densities consistently tracked ahead of the main updraft and actually helped to identify changes in storm motion.  On several occasions the pseudo-GLM densities also indicated that the main center of rotation was shifting prior to the identification of new rotation tracks by the multi-radar multi-sensor algorithms.

Although lightning jumps preceded many of the tornados, forecasters commented that they would have liked to examine time trends for individual storms.  This has been a common theme during previous spring experiments, and was not fully accounted for by plotting swaths of the pseudo-GLM products.

-Scott Rudlosky (pGLM scientist week 3)