LightningCast – EWP Blog

Day 4- Large Hail in Texas

Posted in DSS, GREMLIN, LightningCast, SPG2025 on June 5, 2025 by Kevin Thiel.

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

Supercells in Southwest Kansas

Posted in DSS, GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2025 on June 5, 2025 by Kevin Thiel.

Convection crossing into Hamilton County

Pretty much right at the start of operations, convection over southeast Colorado began pushing east into Hamilton County, KS. Looking at the first gif below (Figure 1 with the Octane 4-panel), you can really see a persistent divergence signal as the storm continued into the county. Additionally, probsevere (located in the top left panel) was pretty high, maxing out above 90%. Next, looking at the LightningCast panels in Figure 2, you can see the lightning jump occurring right as it crosses over the county line. Utilizing these products together and noting radar showing a mid-level meso with 50 dBZ over 35kft, we felt confident to go ahead and issue a Severe Thunderstorm Warning for this cell (shown in Figure 3).

Figure 1: Octane 4-panel with ProbSevere overlaid in the top left panel

Figure 2: LightningCast v1(left) and v2(right) with GLM

Figure 3: Radar Reflectivity with the Severe Thunderstorm Warning

GREMLIN (top left panel in Figure 4 below) did a pretty good job showcasing this cell, as well as another strong cell just to the southwest, however compared to MRMS (top right panel), it didn’t capture the stronger reflectivities as well, and was approximately 5-10+ dBZ off. So if I didn’t have radar access and could only rely on GREMLIN, I may not have felt as strongly about issuing a SVR.

Figure 4: GREMLIN 4-panel

I didn’t grab images of this, however later on, there was a clear decrease in the lightning activity, with noticeably lower divergence and cloud top cooling. This gave me the confidence to cancel my warning early.

Octane and ProbSevere

Later on, the same cell over Hamilton County began slightly cooling again, with ProbSevere noting 59% probabilities (top left panel in Figure 5). Additionally, there was a very clear mesocyclone noted in Figure 6. Using just these two products, I may have been inclined to issue at least a SVR warning. However Octane wasn’t noting much, if any, cloud top divergence or cloud top cooling. Lightning also didn’t look very impressive either. Noting this, I strayed away from any warning issuance (especially considering radar was sampling this storm at 12.5kft), which I think was a good call, at least for this time.

Figure 5: Octane 4-panel with ProbSevere overlaid in the top left panel

Figure 6: Storm Relative Velocity

LightningCast Dashboard for the DSS Event in Dodge City

Closer to the end of operations, the LightningCast dashboard (Figure 7) started showing higher probabilities of lightning, with the Max prob for a 10-mile radius showing 77%, v1 at 45%, and v2 at 30%. There were two supercells several counties west of the event that were expected to track southeast, missing the venue, however with the dashboard and CAMs showcasing the potential for lightning to reach the event, we were confident enough to fill out a DSS form and graphic (shown in Figure 8) with this information.

Figure 7: LightningCast Dashboard

Figure 8: DSS Graphic

It should be noted that v2 only highlights a 30% probability, and later on was ~44% lower than v1 (v1 was at 76%, with v2 at 32%. With this being at the end of operations, we couldn’t see if lightning actually occurred at the event, but I’d be interested to see if v2 actually had a better grasp on the convection tracking southeast and missing the event altogether, or if v1 showcasing the higher probabilities was the better option.

Final Thoughts from Day 4:

The Octane product really shined today, both in increasing my confidence to issue a SVR warning, and in talking me down from issuing a separate warning. I’ve been sold on the Stoplight colorcurve, with no smoothing (top right panel) coming out on top.

– Fropa

Nowcasting Convective Initiation and Evolution with OCTANE, GREMLIN, and LightningCast

Posted in GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2025 on June 5, 2025 by Kevin Thiel.

SYNOPSIS – A remnant outflow boundary from previous convection was laid out across portions of west Texas. Heating and destabilization occurred along this boundary, setting the stage for scattered supercell development where convergence was maximized. Below are some observations and notes regarding data seen in OCTANE, GREMLIN, and LightningCast.

OPERATIONAL NOTES AND FEEDBACK – Nowcasting Convective Initiation with OCTANE and LightningCast.

As is so often the case in setups like this, there was a fairly large area of towering cumulus clouds and occasional attempts at convective initiation (CI) along the outflow boundary. For today’s operational period, I tried a 4-panel combination that included OCTANE products, LightningCast, and traditional satellite imagery (Figure 1).

Figure 1 – OCTANE Speed (top left); OCTANE Cloud Top Cooling/Divergence-no smoothing (top right); OCTANE Cloud Top Cooling/Divergence-medium smoothing (bottom left); VIS/IR Sandwich + LightningCast (bottom right)

As was seen in previous days of this experiment, OCTANE products helped to identify areas of towering cumulus that had the most vertical growth and, consequently, the greatest near-term potential for CI. This is evidenced by the green shading in both the OCTANE Speed and OCTANE Divergence products in Figure 1. One of the potential enhancements to nowcasting CI is LightningCast. While OCTANE appears to excel at depicting where towing cumulus has the most vertical development, LightningCast appears to excel at pinpointing which of those areas of more developed cumulus have a better chance at producing lightning. This essentially provides additional probabilistic information for trying to determine where CI may soon occur, which trickles down to knowing where to focus pre-CI IDSS.

In Figure 1, for example, an increase in lightning probabilities was observed just west of the WFO Lubbock forecast area, where OCTANE was highlighting increased vertical development of towering cumulus clouds. The increase in probabilities, plus consistently high probabilities, provided lead time on where CI would eventually occur. Note the consistently high probability of lightning in that area, as well as increasing probabilities to the south. Two separate supercells eventually developed in this area, and later went on to produce severe weather.

OPERATIONAL NOTES AND FEEDBACK – Nowcasting Convective Evolution and Intensity with GREMLIN.

For today’s operations, radar coverage was not a challenge, but GREMLIN data was still analyzed to determine if there is utility even in cases where radar coverage is sufficient. Today’s event highlighted several important observations about GREMLIN.

1) This is the first event during this week’s experiment in which 60+ dBZ echoes showed up on GREMLIN. This closely matched the 60+ dBZ cores seen on MRMS (as shown in Figure 2 below). It was noted by the developers that 60+ dBZ echoes offer a high likelihood of severe thunderstorms and this was, indeed, the case in today’s event. This suggests that GREMLIN may offer increased confidence in the occurrence of severe weather regardless of good or poor radar coverage.

Figure 2 – GREMLIN Emulated Reflectivity (top left); MRMS Reflectivity (top right)

2) For sustained, deep convection with cold cloud top temperatures and lightning in the anvil, GREMLIN may sometimes erroneously equate this to precipitation occurring at the surface. Note in Figure 3 below the area of 40+ dBZ echoes depicted by GREMLIN over the northwestern part of the Lubbock CWA. This area corresponds to nearby GLM lightning, but note that no precipitation is depicted by MRMS reflectivity or WSR-88D reflectivity (not shown).

3) When thunderstorms are close together with merging anvils, be aware that GREMLIN may treat this as one thunderstorm, instead of multiple thunderstorms, as seen in Figure 3. Note the one cell seen in GREMLIN data near the far western edge of the Lubbock CWA, then compare that with the two cells that actually existed (as seen in MRMS data). It should be noted, though, that GREMLIN did well to capture the most dominant of the two thunderstorms.

Figure 3 – GREMLIN Emulated Reflectivity (top left); MRMS Reflectivity (top right); GLM Lightning (bottom right)

OPERATIONAL NOTES AND FEEDBACK – Nowcasting Updraft Strength with OCTANE

Today’s event provided an interesting opportunity to nowcast two strong updrafts in close proximity to each other. In Figure 4 below, the OCTANE Speed product reveals a strong updraft developing within the divergent area of a nearby thunderstorm’s updraft. The developers noted that this is impressive because essentially the former updraft is strong enough to oppose the already enhanced, and modified, flow around the latter updraft, suggesting an increased risk of severe weather. The OCTANE Speed product appears to better depict what is happening to the flow aloft around both updrafts when compared to the VIS/IR sandwich product alone. I suggest using OCTANE and the VIS/IR sandwich product in tandem with each other when nowcasting convective updraft evolution.

Figure 4 – OCTANE Speed (top left); OCTANE Cloud Top Cooling/Divergence-no smoothing (top right); OCTANE Cloud Top Cooling/Divergence-medium smoothing (bottom left); VIS/IR Sandwich (bottom right)

– NW Flow

Southwest Texas Lightning Product Performance

Posted in DSS, GLM, LightningCast, SPG2025 on June 5, 2025 by Kevin Thiel.

Lightning, and GOES-East vs. GOES-West

Observation 1: GLM discrepancies between satellites

Left: GOES-East LightningCast v1 & GLM FED Right: GOES-East LightningCast v2 & GLM FED 1836 UTC – 1931 UTC 5 June 2025 in southwest Texas

GOES-West GLM 1911 UTC – 1933 UTC 5 June 2025 in southwest Texas (LightningCast outside the domain)

The Midland-Odessa (MAF) forecast area (and nearby upstream areas in Mexico) sits in a weird position where it is well within the GOES-East CONUS domain, but on the edge of the GOES-West CONUS domain (and thus outside the CONUS LightningCast domain), yet within the GOES-West full disk domain. The above images show GLM observations in southwest Texas from both satellites, where GOES-East shows far less lightning (and a downward trend) while GOES-West showed significantly more lightning at the same time (also with a downward trend, but still indicating a stronger storm).

Observation 2: GOES-East LightningCast performance within areas where GLM FED is underestimating

While LightningCast data is not available from GOES-West in this portion of southwest Texas to compare GOES-West v1 vs. v2 as well as East vs. West, the quality of the GOES-East LightningCast product in areas with potentially degraded GLM observations raises an interesting question about how the models perform in this situation.

In the first GOES-East LightningCast loop shown above, version 1 and version 2 generally seem to perform very similarly, likely because of poor radar coverage and data availability. (See RQI image for the area below). Version 1 picks up on a contour of 70% ProbLightning for a developing storm to the northwest of our main cell at 1856 UTC, roughly the same time as Version 2, giving roughly a 20 minute lead time, with the first strike via GLM around 1916 UTC. Version 1’s 70% contour is larger and remains larger than version 2 for the first 10 minutes or so, before both products begin matching closely around the time of first lightning detection. Version 2 then quickly begins downtrending on that cell, seeming to pick up on lightning cessation prior to version 1 does.

Observation 2.5: GOES-East LightningCast DSS Dashboard

This storm impacted our DSS event. At 1955 UTC, DSS was provided to the partner that “lightning will be within 10 miles of the event within the next 30 minutes (by 2030Z) from a storm roughly 30 miles south-southwest of the location (the larger, southernmost storm in the GOES-East loop), a Severe Thunderstorm Warning has been issued for that storm just south of them but the warning doesn’t encompass the event, and that additional convection is going up north of the event, which may also bring lightning within the 10 mile range of the event.”

GOES-East LightningCast DSS Dashboard.

The decision to contact the partner about the DSS event at 1955 UTC was made with the help of the LightningCast DSS Dashboard, which had a max probability of lightning within the 10 mile radius of the event at 90% at the time of the contact. They were told they had less than 30 minutes before lightning was within 10 miles, and 20 minutes after that call, the first GLM strike was observed in that radius. Negating the time it took to fill out the DSS form online in comparison to picking up the phone, the DSS provided to the partner based on the dashboard output was 10 minutes late on onset, but could have been spot-on if the DSS call was provided immediately after the 10-mile radius probability reached 90% instead of waiting to see persistence before calling the partner.

Back to observation 2: GOES-East LightningCast performance within areas where GLM FED is underestimating

Also in the GOES-East LightningCast loop, there is a lower probability contour in the farthest northwest corner of the image at the beginning of the loop. Both versions pick up on it, and both versions go back and forth between characterizing this small bullseye area as continuous/connected to the two storms to its southeast and discrete. Version 2 indicates 50% probabilities briefly, while Version 1 does not. Both have probabilities dropping <10% at the same time, and lightning was never observed.

MRMS radar quality index

– prob30

Lightning Dashboard IDSS

Posted in DSS, LightningCast, SPG2025 on June 5, 2025 by Kevin Thiel.

For Day 4, we were DDC. There was an outdoor event ahead of the convection, and prob lightning did a great job 1) detecting some convection ahead of it and 2) showing that it would be east of our IDSS event.

The animated GIF above shows both versions of the lightning cast, with the outdoor event marked by the “Home”. In this case, both versions accurately predicted lighting (white dashes), and also showed it staying east of the event.

– Updraft

MAF Isolated Convection with LightningCast, Octane, and GREMLIN

Posted in GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2025 on June 4, 2025 by Kevin Thiel.

LightningCast

Towards the beginning of operations, there wasn’t much to look at in the MAF CWA, however just to our south, LightningCast was able to pick up on the cell shown in Figure 1 below pretty well before the first lightning strike. It was interesting to see that v2 increased the probabilities to 50% before v1, however v1 increased to 70-90% before v2 a couple frames before GLM depicted the first lightning flash. So in this case, both versions did well in detecting this cell’s lightning potential, with version 1 taking the lead in the higher probabilities right before the lightning occurred.

Figure 1: LightningCast v1 (left) and v2(right)

Another example of version 1 taking the lead is in a different cell just south of Redford, TX shown below in Figure 2. Both versions caught on to the cell at the same time with the 10% probabilities, however as the cell continued growing, version 1 seemed to hold on to the higher probabilities more so than version 2 before GLM showed the first lightning flash.

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

Octane & GREMLIN

I really liked assessing the cloud top cooling in the Octane 4-panel in the image below. You can really parse out that cell just south of Redford, which ended up also upticking in LightningCast probabilities (not shown). This was a great way to keep up the situational awareness and determine which cells needed more focus, especially being without radar to assist.

Figure 3: Octane 4 Panel

GREMLIN also picked up on this cell, which I thought did a pretty good job. It’s hard to assess whether or not it matched up with radar since we weren’t using radar today, however I think with the lack of lightning, and a newer cell, the GREMLIN imagery looked fairly good.

Figure 4: GREMLIN

This cell later went on to grow fairly tall, with GREMLIN actually depicting a >60 dbZ echo and Octane showing pretty consistent divergence (not shown), so we ended up issuing a warning. I thought GREMLIN did really well, and led to higher confidence in issuing a warning without having actual radar data.

Comparing Octane Color Curves

With little convection in our CWA, I was able to take some time to compare the Octane colorcurves (Stoplight vs. Original). Before today, I tended to gravitate more towards the original colorcurve with Magenta hues as the divergence and the stoplight colors as the cloud top cooling. However the two images below show both color curves at 20:22Z – In this example, the magenta color curve in Figure 6 would lead me to believe the divergence was fairly good in this cell. But the stoplight color curve shows the divergence actually isn’t as good. Comparing this to lightning, GREMLIN, and IR satellite imagery, I like how the stoplight color curve “talked me down” to be more realistic of what was actually going on. So for day 3, the stoplight color curve took the lead.

Figure 5: Octane Stoplight Color Curve (for Divergence)

Figure 6: Octane Magenta Color Curve (for Divergence)

-Fropa

Warning Without Radar Data in Northern New Mexico

Posted in DSS, GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2025 on June 4, 2025 by Kevin Thiel.

Day 3 of the testbed offered a unique opportunity to issue real-time warnings without access to radar data. Having never been in such a situation before, it was an eye-opening experience.

Mesoanalysis showed very steep lapse rates, a long and straight hodograph, high LCLs and a fairly deep mixed layer with relatively low surface dew points. This allowed us to key in on large hail and severe winds being the primary hazards. Additionally, equilibrium levels were only around 9km so hail much larger than 1” was determined to be unlikely.

We issued our first warning upon noticing a rapid uptick in updraft intensity on OCTANE, which showed cooling cloud tops, fast motions, and strong divergence aloft. This storm was located west of Albuquerque in a sparsely populated area so it is difficult to say if the warning verified or not. Gremlin showed a similar uptick in simulated reflectivity which added weight to our decision to warn.

We issued additional warnings as the storm traveled into the Albuquerque area. A second and third cell began to strengthen as well, and two more warnings were issued with the southwest storm looking the most intense on OCTANE. Our mesoanalysis determined that the low-level cumulus field east of the northeastern cell appeared flat and was therefore stable…so weakening was anticipated as it moved off the Raton Mesa.

As expected the northeastern cell began to weaken and dissipate, which was evident on OCTANE and Gremlin. The two cells further southwest continued to look strong, and warnings were maintained into the Albuquerque metro. A hail report of 1” was received at this point on the southern margin of the city.

Lastly, lightningCast showed the northeastern cell begin to weaken before its appearance on satellite degraded significantly. This allowed us to cancel the warning early, in conjunction with noticing the downward trends in OCTANE (weakening cloud top divergence).

During the course of the event we had to keep tabs on a fictitious DSS event, and used LightningCast and its associated dashboard to determine when lightning was approaching their critical threshold (10 miles). LighgtningCast did a good job with lead time as it had 70 percent or higher before any lightning was detected nearby.

– WxAnt

ProbLightning Ending Time

Posted in DSS, LightningCast, SPG2025 on June 3, 2025 by Kevin Thiel.

For Day 2, we were the Wichita Office. Our IDSS event had a high probability of lightning. Our group had a discussion about the idea of “lighting ending”, as that is a common question from outdoor events. In this case, ProbLighting did a great job of forecasting the ending time of lightning by using the time of arrival tool on the back gradient of the convection. Of course this would not work for back building storms or new development, but it performed well in this case. We incorporated that time info into our messaging.

The image above shows the ProbLighting (V2, left, V1 right) with ENL pulses on the left. This time of arrival tracker is shown in white on the left. Unfortunately AWIPS locked up toward the end, but this time of arrival gave a fairly accurate forecast that was used in the graphic.

The image above shows the graphic that we created at 346pm that showed the storms ending at 6pm using the time of arrival tracker on the back side of the Prob Lightning gradient. This turned out to be fairly accurate. In a real scenario, we could have probably briefed this information out to the decision maker.

– Updraft

Day 2- Using OCTANE In Warning Process

Posted in LightningCast, OCTANE Speed Sandwich, SPG2025 on June 3, 2025 by Kevin Thiel.

Synopsis: A broken line of thunderstorms formed along a warm front from southern Oklahoma to east-central Kansas Tuesday afternoon. Storms entered a very moist environment with moderate to high MLCAPE and marginal shear. Due to a southwest to northeast storm motion, the largest threat was flash flooding, if storms became strong, damaging winds and large hail were possible.

Most of the activity in the ICT CWA was sub-severe (with the exception of flash flooding,) however there were times when a few storms pulsed-up enough to potentially produce damaging winds and/or large hail. One storm in particular had a lightning jump (GLM and ENTLN) at 2019Z over Greenwood county. This storm was entering an area that was untapped, however isolation was low.

Image 1 Caption: Snapshot of MRMS Reflectivity at -10C, GLM Flash Density, LightningCast ABI+MRMS, 5 Minute CG Flash NLDN and ENTLN 1 Minute Update Lightning

Using the OCTANE Speed and Direction Sandwich product it was evident that the storm of concern in Greenwood county showed changes in local shear coinciding with the lightning jump. The combination of this product with radar and lightning trends increased my confidence to issue a severe thunderstorm warning for damaging winds for 60 minutes.

Image 2 Caption: GOES-19 EMESO-1 and EMESO-2 CH-02 and Octane Speed products

– Eagle

Operational Feedback of Gremlin, Octane, and LightningCast during a Severe Weather Outbreak in Central Oklahoma

Posted in GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2025 on June 3, 2025 by Kevin Thiel.

I tested the OCTANE, GREMLIN, and LightningCast products during an actual severe weather event on 6/3/2025. My role during this testbed was that of the mesoanalyst.

Initial environmental analysis shows weak to moderate shear, which was determined via ARARS soundings and SPC Mesoanalysis, along with OCTANE imagery showing divergent / accelerating speeds within the storm anvils. VAD hodographs were used as convection developed to see rapid changes within the shear profile during the course of the event (as convection altered the broader environment). Shear increased as the event progressed. OCTANE and LightningCast were both useful showing the uptick in storm intensity as shear increased.

LightningCast was very useful picking out developing updrafts and embedded updrafts within broader areas of convection. We used this product to gauge which updrafts had the greatest potential to become severe in the near term. A strong uptick in lightning would indicate a rapidly strengthening updraft which would warrant further interrogation.

Similar to LightningCast, OCTANE was useful in determining which updrafts were trending towards severe. While in the mesoanalyst role, I would check to see which updrafts looked most intense (warmer colors paired with a very bubbly/convective appearance) and showed strong divergence. Radar analysis would then help us determine which individual cells to warn on, especially if the area of convection is multicellular and warning the entire thing isn’t ideal.

I didn’t use GREMLIN as much, since this area had good radar coverage. However, I did use it to keep tabs on its performance. The product seems to do well with picking out the strongest discrete/semi-discrete cells and potentially struggles with smaller/shallower storms and mergers.

Using these products, and working as a team with good communication, we were able to successfully warn a tornado in the Norman area along with various severe wind and hail.