Conditions were favorable for severe thunderstorms across west Texas on Thursday, June 5, 2025. High instability and shear led to rapid development thunderstorms across the high plains. Initially, a cluster of thunderstorms congealed into one which then split into two. The right mover went on to produce at least 3” in diameter hail and wind gusts in excess of 72mph. Due to the poor radar coverage in west Texas, GREMLIN was useful in supplementing radar and MRMS data. GREMLIN showed features I hadn’t seen in the start of the week, including bean-shaped storms and double updrafts that later split into two storms.

GREMLIN had some odd things occur too. ECONUS GLM did not represent the lightning that was occurring with these storms and it is believed that this may have degraded GREMLIN.  In the loop below, ECONUS GREMLIN produced a fictitious cell northeast of the left and right movers. It also lagged a bit before it showed two strong cells, especially the southern storm.

Four Panel-GREMLIN EMESO-1 (top left,) MRMS -10c (top right,) GREMLIN ECONUS (bottom right,) and CH07 (bottom left.) In this example you can see the stronger storm to the south

Here is a single image of the bean shaped cell that produced at least 3” hail.

LightningCast was useful for situational awareness and messaging our partners for the DSS event. We noticed V2 was a little better at maintaining the high probability of lightning (greater than 90%) than V1 in mature convection.

LightningCast proved to be useful for our fictitious DSS event in west Texas. V2 was faster to increase the probability of lightning prior to lighting occurring at the event (below.) It was also faster to show lightning cessation. There was a brief lull in lightning mid-way through the operational period and both V1 and V2 showed about a 20 min lead time of the probability of lightning decreasing in the next hour. V2 stayed slightly elevated compared to V1, but both highlighted that there was still a high probability of lightning in the next hour.

Lastly, OCTANE (below) proved to be useful again in warning operations. Robust, mature convection was ongoing and while it was “off to the races” in west Texas, the speed and divergence products continued to the tight gradient of speed divergence. We noticed that the compressed color scale was more “eye catching” to show the tight gradient. Below is a picture of the speed/direction divergence product with sampling turned on. The overshooting top was at an impressive -85C with winds out of the west at 50 mph. In this example, the gradient on the west side of the storm helped maintain our confidence of a powerful storm.

– Eagle

LightningCast

For this first day, I started out looking at Lightning Cast to gain familiarity with version 2 and see how it compares to version 1. The first thing I noticed was in southwest Pueblo County, where there seemed to be fairly frequent lightning. Version 1 in the top left panel (Figure 1 below) actually decreased in probability from 70% to 50%, whereas Version 2 in the top right panel remained at 70%. With both GLM and ENTLN depicting ongoing lightning, I think both versions should be showing higher probabilities. I’m wondering if it’s because both versions are so focused on the convection moving into southeast Pueblo County that they’re less focused on the stratiform lightning/less mature convection?

Figure 1: Four panel comparing LightningCast v1 (left panels) and LightningCast v2 (right panels)

Additionally, I tested out using the LightningCast dashboard for Fowler, CO beginning at 3PM MDT. One interesting thing to note was that it seemed to match better with the version 2 LightningCast in AWIPS versus with version 1, however both versions weren’t too far off. In the Figure 2 below, the left panel (version 1) shows between 30-50% probability of lightning, whereas the right panel (version 2) shows Fowler (purple dot in the image)  right on the border of the 70% probability. Comparing that to the dashboard (Figure 3) for the same time, the yellow line (version 1) depicts a 54% probability, with the green line (version 2) showing an 84% probability for 21:18Z. With MRMS reflectivity at the -10C level showing a cell up to 42 dBz just southeast of Fowler, I would tend to lean towards utilizing version 2.

Figure 2: LightningCast v1 (left panel) and LightningCast v2 (right panel)

Figure 3: LightningCast Dashboard

One final note on the LightningCast Dashboard – I thought it was interesting to see that version 1 in Figure 4 below, the yellow line (version 1) shows two separate upticks in lightning probability versus the green line (version 2) showing a steady decline in probability.

Figure 4: LightningCast Dashboard

GREMLIN

I was also able to look at GREMLIN, which was my first time assessing this product. Figure 5 below shows a four-panel, with GREMLIN (top left), MRMS Reflectivity (top right), Satellite IR sandwich (bottom left), and GLM Flash Extent Density (bottom right). Just looking at MRMS and IR, the first cell that draws my attention is the cell in southeast Pueblo County as it has higher reflectivities and cooler cloud tops. The cell in southern Otero county looks like the cloud tops are slightly warming with time. However once we start looking at GREMLIN, those two cells look to go back and forth in reflectivity, leading to less confidence in overall intensity. If I were located in an area with poor radar coverage, or if a radar was down and I had to rely on GREMLIN, it may not be straightforward as to which cell could eventually warrant a warning.

Figure 5: Four Panel comparing GREMLIN (top left), MRMS Reflectivity (top right), Satellite IR Sandwich (bottom left), and GLM (bottom right).

That being said, Figure 6 below shows a screenshot of the same four-panel at 21:41Z, which shows GREMLIN having a pretty good grasp on the convection in Stanton and Morton counties (just outside of the PUB CWA). So in this instance, confidence in the GREMLIN product would at least be higher than the previous example shown.

Figure 6: Four Panel comparing GREMLIN (top left), MRMS Reflectivity (top right), Satellite IR Sandwich (bottom left), and GLM (bottom right).

Final Thoughts for Day 1

Overall I enjoyed testing out both of these products. I definitely want to get more hands-on experience with GREMLIN as well as the LightningCast dashboard in order to see these in different scenarios/environments.

– Fropa