With both discrete and cluster/multicell/linear storm modes, the cloud top cooling, speed, and divergence products proved fruitful in identifying convective intensity trends.

(Sorry, the gif got messed up a little bit)

Top right: OCTANE Speed

Others: OCTANE Cloud Top Cooling (stoplight) and OCTANE Divergence (blues/purples)

The speed product showed not only the motion of the storm tops and the acceleration tendencies of the storm top features, but also highlighted (through the texture and color curves) the presence of other storm scale features like the overshooting tops and above anvil cirrus plumes. The color curve had been modified for this product to be the “compressed” color curve, which made gradients stand out. Additionally, this provided information about the environment the storms were tapping into, in this case showing that storms had ample shear to tap into and use to persist.

The divergence and cloud top cooling products were beneficial at different stages of life. The cloud top cooling products were a bit more useful in the initiation stage of storms, showing strong intensification of new updrafts, but became less useful as the updrafts became better established because the cooling was not the same magnitude you would expect from the initiation stage and it stood out less.

The divergence product felt useful in both of these stages of life, but especially once the storm had matured, since the relative strength of signals were about the same during both (i.e. same pink/red hues). While the re-intensification of the updrafts that cycled was signaled by the re-appearance of the green colors, the persistent signals of strong divergence gave better insight into the intensity trends over the storm’s lifespan compared to the cooling product, which was more instantaneous in nature. Once storms reached the mature phase, the channel 13 IR imagery became a better way of assessing storm top temperatures (not shown).

On the DSS front, the Cloud Top Cooling was more beneficial when used in tandem with LightningCast (not shown) during the initiation stage to assess the storm/updraft motions and decide whether DSS calls needed to be made. The early indication of convective cloud top cooling was a signal to forecasters that the clouds would likely become strong enough in the near future and would begin posing a lightning threat to Rudy’s event.

– prob30