Category: GLM

LightningCast V1 vs V2

Posted in GLM, LightningCast, SPG2026 on by Kevin Thiel.

With an ongoing storm, LightningCast version one featured a “lobe” of higher probabilities extending to the south/southeast. Version 2 didn’t have as pronounced of a “lobe” at the same time (Figure 1). Later on, GLM did pick up on flashes extending down to the south/southeast (Figure 2). To me, the signal for the lightning potential was clearer in the version 1 of lightning cast.

Figure 1. Conus Day Cloud distinction, GLM Flash Extent Density, NLDN CG Flashes, ENTLN Cloud Flashes, Lightning cast V1 (left contours), and lightning cast V2 (right/contours) at 1901z.

Figure 2. Conus Day Cloud distinction, GLM Flash Extent Density, NLDN CG Flashes, ENTLN Cloud Flashes, Lightning cast V1 (left contours), and lightning cast V2 (right/contours) at 1911z.

-wxboi

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HWT day 3

Posted in GLM, LightningCast, SPG2026 on by Kevin Thiel.

Realtime blogging today….(taking notes on the fly vs waiting until the end of the day)

IDSS begins….

Ltg occurring in PA but not being detected by Ltgcast without MRMS over over central PA at 1852  Apr 29

MRMS ltgcast with MRMS is clearly superior to ltgcast without MRMS as the MRMS version clearly showed the ltg occurring  over central PA at 18:52

Use the planview ltg data on awips to verify ltgcast as it shows up quicker then on the dashboards.

Something is not correct…lots of ltg data showing up over our circle(KCRW) point, but it is NOT showing up on our ltgcast display board!?!? (See AWIPS plot below and match that up with the LTG cast board)

 

Lena gets another star as she is very good at picking active weather points for IDSS locations for this HWT.
2053 UTC – ltgcasat seems to be once again “cheating on itself” as AWIPS GLM is showing lots of ltg occurring over our IDSS site, but th eltg data is NOT plotting in the ltgcast board. Screenshots below: (note the GLM is ramping up again)

White Circle above is our IDSS point (KCRW airport)

In summary,

The MRMS version of lightningcast is superior to the non MRMS version. MRMS picked up the ltg in PA while the non MRMS version failed to pick up lightning (i.e., zero probs indicated and GLM flashes were occurring.

HOWEVER….GLM data was showing over our IDSS site as seen in the AWIPS imagery, but th eltg data was NOT plotting in the lght cast ltg boards. Something is not right and this needs to be looked at (Another way to say this is ltg cast is cheating itself….the ltg is occurring but it is not plotting the data on the ltbg boards.

I need to add that I used multiple boards at once

I wish it wasn’t so time consuming to set up things when we go into ops

Lena is very good at picking IDSS points.

Thanks to Dr Apke for going over the OCTANE in a bit more detail with me (and my group, I learned more today).

-Mesovortex

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Southwest Texas Lightning Product Performance

Posted in DSS, GLM, LightningCast, SPG2025 on 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

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High Confidence in Progressive/Weak MCS

Posted in GLM, LightningCast, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

KSHV radar trends illustrate a cold-pool dominated, weak MCS approaching the NW corner of the CWA. Many satellite products illustrated a consistent mainly sub-severe weather episode unfolding giving increasing confidence in the near-term forecast and expected impacts. Focus would be on any stronger individual updrafts for potential isolated severe thunderstorm warnings.

Overall, there was high confidence in approaching thunderstorms per radar and LightningCast data pinpointed the ongoing widespread nature of the convection, given several embedded impulses of GLM spikes behind the leading southeastward surging outflow boundary:

East Octane SpeedDirCTD-CTD_4Pan procedure provides more calculated parameters on top of RGB and ABI products to quickly diagnose convective strength/intensity.

The top 3 panels below (OCTANE speed, direction and Cloud-top Cooling and Divergence) identify a large-scale cirrus canopy with embedded updraft impulses.

Situational awareness was enhanced by adding on local KSHV and KLZK radar which helped to identify a SSW to NNE boundary and associated CI ahead of the main line, which OCTANE products began to illustrate (see center of each product, identifying increasing speed/directional divergence colocated to the convection along the boundary)

Given the environmental parameters, this would have been a location to examine for the potential of a severe thunderstorm warning, especially if associated radar trends (RIJ via radial velocity) indicate increasing downdraft wind potential.

– RED11248

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Tracking Storm Strength With GLM and OCTANE

Posted in GLM, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.
The GLM RGB, combining flash extent density and minimum flash area, highlighted the intensity trend of a cell in the northeast corner of the FWD CWA. The yellows of the RGB also corresponded with the uptick of cloud top cooling signatures shown from the OCTANE product. Using these products together I was able to track the intensity of thunderstorm, which took another uptick towards the eastern border of the CWA. The GLM RGB is definitely a useful tool in reading both the characteristics of the flash length and the flash density.
The OCTANE cloud top divergence product here is overlaid atop the visible satellite imagery with the cloud top cooling product, which may look a little messy to look at at first glance. After some practice with the product I was able to learn to pick out both the cooling and the divergence in a strong convective cell. In the third image I did remove the divergence product to have a good look at the cloud top cooling and visible satelitte signatures. After going back to the combination of the two however I found it easy to read what was happening among both the divergence and cloud top cooling with both displayed. I did like having cloud top cooling displayed on top of the divergence product as the divergence product was broader spacially and it made more sense to have the smaller scale cooling signals pop up above the divergence display.

 

 

-Joaq

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Developing and Splitting Cells in Sterling County TX

Posted in GLM, GREMLIN, SPG2024 on by Kevin Thiel.

This lengthy post will cover a number of interesting observations with developing and splitting cells near Sterling County TX. This post will mainly focus on GREMLIN, but also a few other products.

Initially, we were focused on new updraft development Glasscock County TX. GOES-E GREMLIN (left panel) depicted Z values of about 57dBZ. KMAF comp reflectivity (right panel) was also picking up some 50+ dBZ. The 0.5 slice on KMAF (middle panel) was yet to really show anything of interest. This is evidence that GREMLIN is picking up on situations where echoes aloft have not yet started reaching near the ground. This has a degree of predictive value.

 

The loop from here shows that this storm then proceeds to split as it moves into Sterling County TX. The storm split is apparent on the KMAF lowest slice and comp reflectivity, as early as 2020Z. On GOES-E GREMLIN, the split does not start to show up until 2040Z, and is not readily apparent and clear until 2100Z.

 

So, let’s look a little closer into why GOES-E GREMLIN may have struggled with picking up the split. The loop below compares GOES-W satellite imagery (left panel) with GOES-E satellite imagery (right panel). While GOES-E data masks the updraft of the left-mover under the anvil from the right-mover, GOES-W has a better view of the left-mover updraft.

 

 

 

 

Comparing GOES-W GREMLIN and GOES-E GREMLIN, it’s clear that GOES-W had the better view of the left-mover updraft, and picked up on the split much more accurately (though it was low on dBZ values). On the contrary, GOES-W GREMLIN did a much less consistent job in handling the right-mover.

–Insolation

From a GLM perspective, it’s clear that GOES-West GLM sensor had a better view of the left split updraft and lightning activity than GOES-East. The flash extent density product shown below detected an increase in activity much quicker on GOES-West than its east counterpart. This may be due to the less inhibited view GOES-West had of the updraft looking at it from an angle compared to a more top-down view GOES-East had, which may have been blocked by water droplets or hail near the top of the thunderstorm.
-Joaq
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GLM Trends In A Warning Decision

Posted in GLM, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

Severe thunderstorm and tornado warnings were issued partially driven by the increasing intensity of GLM FED. With the indication of a strengthening updraft due to increasing lightning activity atop the convergence signature on radar, a warning decision was made for both damaging winds and a tornado threat.

OCTANE cloud top divergence also highlights the strongest thunderstorms in our CWA below.

 

-Joaq

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Warning vs DSS – “WFO DMX”

Posted in DSS, GLM, GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

It was interesting when comparing the Warning side of the house today versus the DSS side. When we (Cumulus and Kadic) were discussing this and picked two of the tools we used the most, there were similarities and differences:

For Warning Ops: OCTANE and LightningCast

OCTANE proved very useful in interrogating convection. LightningCast was also a helpful diagnostic tool in highlighting the potential for and track of intense convection when used with ProbSevere.

OCTANE:

Here’s a look at 2 particular instances from OCTANE:

A combination of cloud top cooling in OCTANE and subsequent divergence aloft was a helpful clue in assessing the potential of a storm that was distant from the radar. It was caught a little later in analysis, but OCTANE proved helpful in diagnosing the storm and deciding to pull the trigger.

 

 

This next instance was a warning that was issued solely using OCTANE and seeing how well it lined up with radar. The warning targeted the center of where the maximum storm top divergence was taking place, and then stretched down towards the south to account for parallax. The warning decision was made for the impressive cloud top cooling and pronounced divergence that appeared in the scans leading up to the warning. The panel on the top left shows the OCTANE speed, and it transitioned to a blue color leading up to the event.

 

 

LightningCast and Radar:

As the line shifted east into the area, ProbSevere stood out, while the LightningCast steadily increased. The left hand panel depicts GREMLIN, and it properly highlights the southernmost storm as being the most intense. Unfortunately, not every storm that we issued warnings for got a specific screenshot, but when looking at LightningCast, areas that were likely to experience 10 or more flashes with a 70% probability seemed to correspond well with ProbSevere values would support issuing warnings.

Below is the example of what MRMS looked like the moment DMXSVR005 was issued solely based on OCTANE. Much of the SVR encompassed the highest LightningCast values with a probability of 10 flashes of 70% in yellow and the various ProbSevere contours. Again, this highlights how useful these tools can be in performing storm interrogation. However, when thunderstorms are numerous, this may be a lot to run through. They are definitely useful tools in the tool belt, though.

For DSS: LightingCast (especially the Dashboard) and GREMLIN/GLM.

– LightingCast: I REALLY like the form and Dashboard. It helps focus on the DSS site specifically and organizes the data really well to where I would feel comfortable explaining/showing an EM the graph of   lightning probabilities. Honestly, I could bring this back to my home WFO right now and use this for DSS events this summer. A couple things that could be added to make it even more awesome: adding more options for ranges (right now there is only 10 miles, perhaps adding 15 and/or 20 miles). Folks could then choose which to display in the graph. The other thing (fairly minor), perhaps reversing the size of the bubbles for the GLM data (smaller range, smaller bubble). But, this is personal preference – maybe if this could be customized by the user like the colors?

– GREMLIN/GLM: GREMLIN followed the storms a lot better today (seems to do better with more intense storms versus run of the mill/sub-severe ones). I used a two panel display with GREMLIN on the left and MRMS on the right with GLM and LightningCast and compared the two. I used time of arrival for the storms to 10 miles outside the DSS event and also at the site itself. GREMLIN was able to keep up with MRMS really well! I am becoming more and more convinced that this could be a really great product to help if a radar goes down or there is a radar hole (in data).

Overall, it seems as though OCTANE was used more for warning ops versus DSS, but LightningCast was used by both the warning operator and DSS forecaster.

Forecasters Cumulus and Kadic

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HGX Convection impacting the Car and Truck Show in Burton, TX

Posted in DSS, GLM, LightningCast, NUCAPS, OCTANE Speed Sandwich, PHSnMWnABI, ProbSevere, SPG2023 on by Kevin Thiel.

Initial setup for the HGX vicinity showed several cells to the north and east of the DSS site, propagating southeastward. The strongest cell, pictured below, had a PSv3 of 73%, while PSv2 remained as 56%.

We issued a warning for a northern cell moving into the CWA into Madison county, based on a -70C cloud top brightness temp and PSv3 total prob over 70% (had been climbing from the 50s fairly steadily). But the cloud top shear noted by Octane was not strong (~20-25 kts), so the warning was very borderline. Just a couple scans later, it lost most of its texture on the vis imagery and lost its shear in the Octane direction product. Cloud tops warmed a bit as well.

00H NUCAPS-Forecast (NF) is showing moderate CAPE now (1st image below), which may help explain the messy sub-severe multicell clusters, but the forecast valid at 02z this evening shows a resurgence in the CWA (2nd image below).

Looking to our NW, one of the stronger cells is outside our CWA, but the Octane direction is showing good cloud top diffluence.

The PHS SCP forecast valid at 20z looks to be around 2-4 over our area, although this doesn’t match well with the SPC meso page SCP, which focuses high values W of our CWA.

The 21z PHS MUCAPE (15z run) looks like it has insane values of 6000-7000 J/kg near the coast and just offshore. This is much higher than the SPC meso page, showing 3000-4000 J/kg at most.

Looking at the optimal application of LightningCast, it seems that the point-based meteogram would work best for CI and in situ developing convection, versus storms propagating into the area. In our case here, at the DSS site, the point-based LC probs are low, suggesting little concern. But we can see from the GLM FED data that there are mature cells with lightning just to the NE that will probably move near the site in the next hour, which certainly poses a safety concern.

The NUCAPS sounding near Victoria (far SW CWA) showed a lot of CAPE and DCAPE, but a rather dry profile. This is confirmed by WV imagery over much of far S TX.

22z PHS Composite Reflectivity (above image) compared to 22z MRMS Composite Reflectivity (below image ) depicting PHS struggling on timing as the cluster of thunderstorms propagate from northwest to southeast.

Late in the event, this cell is showing slow strengthening on PS — currently both v3 and v2 have 40% total.

– Edgar and Harvey Specter

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