LightningCast in the Rockies and Appalachians

Forecasters are working in the Amarillo, TX and Columbia, SC county warning areas today. One tool they are evaluating is ProbSevere LightningCast, which helps forecasters by providing objective guidance on lightning potential in the next 60 minutes. 

Afternoon thunderstorms on high terrain are a common occurrence in warm weather. Upslope flow can provide lift for convective initiation. It's difficult to monitor all of the convection developing across a region at once, but LightningCast can help forecasters quickly see which clouds are glaciating and quantify the near-term lightning potential. 

Lead time to the first GLM flash varies widely, but we've found that on average you can expect about 20 minutes of lead time to lightning initiation, measured from the 25% threshold. We are still trying to skillfully extend the average lead time to initiation.

Out east, a short wave trough is forcing convection today in and around the Appalachian Mountains. One new product that forecasters are looking at is the probability of ≥ 10 flashes in the 60 minutes after a GOES ABI scan. This product is meant to give forecasters a heads up on intensifying convection, specifically the initial intensification from benign thunderstorm to one that could develop into a severe threat. The ≥10-flash probability is also an indicator for an increased chance of a cloud-to-ground strike.

In the animation below, two cells achieved flash rates > 10 flashes. On the eastern cell, LightningCast had 35 min (10 min) of lead time to the first 10-flash obs, measured from the 10% (25%) contour. On the western one, there was about 10 min (5 min) of lead time from the 10% (25%) thresholds. Users should note that we have found the P(≥ 10 flashes) generally produces better lead time in "clearer" or "cleaner" scenes, with little convective debris near the developing cells.  

- John Cintineo