Every Cloud Has a Silver Lining - Satellite-Based Mesoanalysis

Satellite-based observations have become a larger part of an operational forecaster’s toolshed with each passing decade. Over the past 10 or so years since the launch of the GOES satellites over North America, forecasters now have access to extremely high-resolution, high-quality data. That data can be used for a wide array of potential benefits, and this satellite HWT is designed in large part to show us how we can widen out that repertoire even more.

With that in mind, I’d like to start out this Hump Day blog post by discussing one of the products that has not been featured as prominently in my previous blogs - GXI water vapor data. In essence, the next generation of weather satellites (GEO-XO) will have the kind of sensitivity that lets us really drill down into the absorption bands to see some neat stuff. That kind of capability won’t arrive until the 2030s, so for this week we are taking a look at what the data could look like via HRRR simulated satellite data.

Figure 1: WVT Ratio from the HRRR (left) compared to Split Window Moisture on GOES-East (right).

As you can see above, there are limitations to this analysis. For one thing, even perfectly initialized models are going to struggle to carry cloud cover forward given its sensitivity. And for another, models are not going to perfectly initialize.

Still, if you squint and look across the eastern portions of NWS Aberdeen's CWA, there is an area of somewhat lighter grey feeding into the cloud band on the HRRR. This is suggestive of a potential moist pool in the region. Actual observations of this would help forecasters dominate the mesoanalysis space like never before.

Perhaps one of the most powerful uses of mesoanalysis tools came from the OCTANE speed-direction tools today. I have spoken at length about those tools, so won’t spend too much time on them. This gif just does a great job of summarizing what we might be able to do:

Figure 2: OCTANE Speed (top left), Direction (top right), Cloud Top Cooling (bottom left), and Day Cloud Phase (bottom right)

Here we have a storm on the north end of the cluster (yellow OCTANE speed, purple OCTANE cloud tops) and developing updrafts to its south-southwest. Those updrafts are occurring in an area of boundary-layer cumulus (shown well by their northeast or yellow motion in the Direction panel). Further to the east, there are clouds oriented along two axes: an area of HCRS (red in the Direction tool), and an area of stable billow clouds (yellow in the Direction tool). Knowing your mesoanalysis, this provides a tell that the northern updraft is likely to wither as it enters a stable boundary layer, which it did. It’s also a tell that further south, updrafts won’t have the same issue. As of the time of this writing, a supercell has developed out of that southern cluster.

This author would be remiss if they didn’t mention the in-person IDSS potential offered by the Lightning Stoplight tool. This has also been discussed previously, so I won’t belabor the details too much. But the ability to display a dashboard from your browser with basically a color-coded area showing how long it has been since the last lightning strike will go a long way toward helping partners understand when DSS activities may restart.

Figure 3: Lightning Stoplight in its web-browser-based glory.

Sabrina Carpenter

FGF CTC CTD Testing

Today's DSS event brought us to the wonderful state of North Dakota in the FGF CWA. Unfortunately with no lightning at either DSS event today, I did not get to use the GOES Stoplight product, so I used Octane again. I continue to be highly impressed by the utility of the OCTANE products. You know the saying “A picture is worth a thousand words”? Well, to me, that is exactly what the cloud top cooling and divergence product embodies. There are so many features that can be picked out from this. Near the bottom left, there are multiple updraft attempts that try but most fail. It shows multiple storms developing in McPherson and Dickey Counties with cooling cloud tops and increasing cloud top divergence. Further to the west in Emmons county it shows a cloud top cooling signal but it ends up disappearing and subsequently the cloud top divergence decreases. Pairing all of the imagery with a visible band really gives some nice textures to the picture where you can easily point out quickly developing features. I find myself continually migrating back to the Octane products for situational awareness as storms approach the DSS event.

Figure 1: East Meso1 Cloud Top Cooling and Cloud Top Divergence with ENTLN lightning data overlaid.

Dry Thunderstorms

LTG DSS with LTG Cast and Stoplight

 Upon starting the shift we had a supercell that was about 1 hr out from our first event. In operations our DSS forecaster would have immediately informed our partner that the cell (which had 1” hail report) is barreling in from the southwest.

Both versions of the LTG cast were providing a 70% chance of LTG within the next hour as well, with convection out ahead of the main supercell the heads up notification would also have included this information.

45minutes later we had our first lightning strike onsite ahead of the main supercell.

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Activity began to wind down by 2030Z

An all clear call would have been made at 2100Z with the stoplight product largely vacant of any lightning detection. MRMS-10C was also outside of the 8mile range ring with little build up expected upstream. Lightning cast had also dropped to around 10%.

IsthataTOR

GEOXO storm development and LightningCast DSS

 The GEOXO Sim 5.15um band and WVT ratio showed supercell or at least thunderstorm development near Gettysburg by 21Z. However the initialization of the upper level cirrus was underdeveloped and the main severe warned thunderstorm was farther north than observed. The lower level cumulus also appeared to be underdeveloped. There is a clear region in the sims where higher moisture is present and dryer air exists on either side, with the thunderstorms developing on the western boundary line.

Figure 1: GEOXO Sim 5.15um band and WVT ratio on top with observed GOES-19 IR an visible imagery on bottom. First frame shows Observations at around 20Z compared to the model and the second frame is in the future on the top an hour later.

While not severe or as intense as the Sim suggested, storms did develop and provided an interesting borderline case where LightningCastv1 showed barely 10% and v2 showed barely 30% chance of lightning in the next hour within 5 miles of the Gettysburg DSS location. A lightning strike occurred roughly miles from Gettysburg that was detected by the ENTLM and the Stoplight tool maybe 2 miles to the east. In this case, the addition of MRMS was clearly helpful in detecting the initial nearby convection.

Figure 2. LightningCast comparison between version 1 and 2 and parallax vs no parallax adjustment.

Cloudius

Overview: Week 3, Day 3

Day 3 started with our debrief from Tuesday, along with a focus group activity for GeoXO lightning mapper capabilities. I showed forecasters SZA imagery near sunrise during a period of glare from the GOES-East perspective near sunset. Overall forecasters felt the cloud tops were more 'washed out' by the brighter visible channels, but mentioned the important feature from the Day Cloud Phase Distinction is often the cloud phase before the overspreading anvil cloud begins. 

Traditional Day Cloud Phase Distinction RGB

SZA Day Cloud Phase Distinction RGB

Wednesday targeted the Northern Plains again, with the cold front being are only source of lift and deep layer shear that we can pull from this week. We decided to localize the forecasters to NWS Grand Forks, ND (FGF) and Aberdeen, SD (ABR), and each had two DSS events so they could leverage the LightningCast SuperDashboards.

1PM

Storms were slow to develop early in the forecaster period with a bit of cloud cover making the Synthetic GXI imagery less usable, so the product developers took both offices on a 'tour of Europe' showing off the Water Vapor Transmittance product from the Meteosat-12 FCI. This led us back to the states where we talked more about colormaps for WVT and what forecasters preferred. I made a display as part of that discussion. Upper left is WVT with 'flipped' colormap, upper right is WVT with the origional colormap, lower left is WVT with a red-green colormap made by a forecaster in the previous week, and the lower right is PWATs from the most recent HRRR run (18Z).

 2 PM

Forecasters in both offices focused mostly on DSS tasks early in the forecast period, along with comparing OCTANE's CONUS and MESO products. Additional discussion centered around the Lightning Stoplight tool and debating the 'optimal' color table to convey the intended actions from those viewing the product.

As thunderstorms approached the mock-IDSS events forecasters interrogated LightningCast data and discussed its applications, along with the desire to have variable ranges for the dashboard web display. We did run into an interesting case where a thunderstorm initiated over a narrow band of cirrus clouds, which may have impacted signals from OCTANE and LightningCast.

To end the day, I spammed AWIPS looking for sunrise imagery to show off SZA (thanks Justin for turning on the feed so early!)

Fog and low clouds from the marine layer along the California coast from the Day Cloud Phase Distinction RGB (SZA left/traditional right)

Valley fog over the Appalachian Mountains in the morning from the Day Snow Fog RGB (SZA left/traditional right).

Kevin

Persistent Severe MCS and Downbursts in Southwestern South Dakota

 1. Convective Initiation & MCS Evolution (1900 UTC)

The early afternoon of 2 June 2026 was marked by the development of a persistent mesoscale convective system (MCS) over Fall River County, SD as shown in Figure 1 below.

Satellite Observations: The 1900 UTC composite satellite image shows the system advecting east-northeastward, exhibiting rapidly increasing ice-phase cloud tops and a significant rise in lightning flash rates.

Structural Signatures: At this stage, the MCS already exhibits a well-defined bow echo complex and a prominent rear-flank dry-air notch. These features indicate
that the system is efficiently processing dry mid-level air to generate strong surface outflows.

Figure 1: Composite SZA cloud phase distinction, MRMS reflectivity, and LightningCast probability product image at 1900 UTC 2 June 2026.

2. System Intensification and Dual Bow Echoes (2030 UTC)

By 2030 UTC, Figure 2 shows the convective complex underwent further intensification and expansion as it tracked across southwestern South Dakota.

Complex Organization: The system evolved into a more formidable MCS consisting of two distinct bow echo complexes.

Severe Potential: Each bow echo was accompanied by its own rear-flank dry-air notch. This dual-notch presentation signaled a marked increase in downburst potential, as the system became increasingly organized and capable of producing widespread damaging winds.

Figure 2: Composite SZA cloud phase distinction, MRMS reflectivity, and LightningCast probability product image at 2030 UTC 2 June 2026.

Figure 3. Comparison between the GOES-19 (G19) sounding retrieval 90 km SSE of Rapid City, SD (left) and the Rapid City (UNR) RAOB sounding at 1800 UTC 2 June 2026 (right).

3. Thermodynamic Environment: Rapid City (1800 UTC)

An analysis of the 1800 UTC environment in Figure 3 explains the high-end wind potential observed.

Sounding Profile: A comparison between the GOES-19 sounding retrieval and the Radiosonde observation (KUNR) at Rapid City, SD, reveals a textbook "hourglass-inverted-V" profile.

Instability & Wind Potential: The environment was characterized by large CAPE (1014 to 1584 J/kg). Correspondingly, the Wind Gust Potential (WGP) was calculated between 41 and 47 knots, providing strong evidence for the severe gusts that followed.

4. Regional Validation & Surface Verification

Regional sounding data further confirmed the widespread nature of this volatile environment.

NUCAPS Comparison: A NOAA-21 NUCAPS sounding retrieved at 1919 UTC approximately 150 km southeast of Rapid City showed excellent structural agreement with the UNR radiosonde (RAOB).

Key Ingredients: Both profiles highlighted favorable wet-bulb zero heights for evaporative cooling and robust downburst generation.

Ground Truth: This thermodynamic setup culminated in a significant surface event: a severe 55-knot downburst wind gust was recorded at Cactus Flats, SD, at 2043 UTC— aligning well with the high WGP and structural signatures identified earlier in the afternoon.

Figure 4. Comparison between the 1919 UTC NOAA-21 NUCAPS sounding retrieval 150 km SE of Rapid City, SD (left) and the Rapid City (UNR) RAOB sounding at 1800 UTC 2 June 2026 (right).

StormRangerWX

Moisture advancing east in pre-convective Wyoming environment

 Simulated GeoXO Imager (GXI) imagery revealed the westward extent of higher moisture in the pre-convective environment of eastern Wyoming this afternoon.

Figure 1 shows the water vapor transmittance (WVT, derived from the 0.91 µm channel) in the left panel and the 5.15 µm brightness temperature in the right panel over a five hour period from 16-20 UTC..  A dashed green line indicates the approximate westward extent of the deeper moisture as estimated from the WVT imagery. In this “inverted” color scheme, drier areas appear darker in WVT (as does higher terrain), and moister areas appear whiter; high-topped clouds generally appear dark.  In the last frame of the loop, convection initiates near Douglas along this moisture boundary on the southern end of this green line.

While WVT is sensitive to the total column water vapor, the 5.15 µm channel is only sensitive to water vapor in lower levels, where lower brightness temperatures generally coincide with higher low-level moisture.  It is interesting to note that the WVT and 5.15 µm gradients do not always align with each other, possibly suggesting an evolving vertical distribution of water vapor.  Our future plans include developing methods to utilize these differences to derive information about depth of moisture in the column.

Figure 1: WVT (left panel; inverted color scale so whiter colors=more moist). The green dashed line indicates the approximate westward extent of deeper moisture as estimated from WVT. 

VortexTilting

CYS Lightning DSS

 For context, there ended up being no lightning within 15 miles of the DSS event. With storms developing on the Laramie Range and the event in Fort Laramie, this case was excellent given developing convection upstream. The LightningCastV1 and V2 looked different despite having no radar data from KCYS. Near the beginning, LightningCastV1 appears more bullish on the 10% and 30% contour nearly over the event range ring while the V2 is closer to the western edge of the 15 mile range ring.

Figure 1: LightningCast-ECONUS-compare panel.

LCv1 vs LCv2 probabilities for GOES-East and GOES-West were the most interesting results of this case. Objectively, the GOES-East V2 chances for lightning ended up performing the best with no strikes. The environment supported dominant left splits which ended up happening with 2 storms. The southwestern storm ultimately decayed but the lingering weak right mover was slightly problematic for chances of lightning near the end of the event with cloud flashes near Bordeaux, WY. The northwestern storm initiated near Laramie peak and ultimately threw a dominant left split away from the DSS event. The most interesting part was the chance of lightning from the 4 options ranged from nearly 20% to nearly 75% around 2120 UTC. What was notable at that time on the radar was the dying right split SW of Bordeaux, WY, and the dominant left split was moving away from the DSS radar just west of Sibley peak, WY which would make me think of lightning potential being very low. This is not to diminish the potential of the product but to raise awareness that different data sources resulted in a 65% difference in chances for lightning.

Figure 2: LCv1 vs LCv2 probabilities for GOES-East and West.

Dry Thunderstorms

Octane CONUS vs MESO

 I focused pretty closely on the comparison of the CONUS Octane Speed vs the Meso Octane Speed product.

Overall I found that the CONUS product was a bit too coarse to really pick up on the main features of interest.

CONUS 

MESO

The example above really highlights the yellow and dark blue hues making it easier to ID the rapid changing environment as opposed to the CONUS which you can kind of see with the green. But you completely miss the dark blue speed minima found in the MESO

Couple more examples below showing the stark difference between the two.

IsthataTOR

The Think Pony Club: Providing Decision Support Using New-Age Satellite Products

 Picture this: you’re out on the open prairie of Wyoming. The wind is whistling through the grass. The late-afternoon sun shines against the towering clouds that have made the Great Plains famous. Spread out in front of you along the hallowed and historic grounds of Fort Laramie, dozens of people wait in folding lawn chairs. There are picnics and music and the shouts of children playing in the warm June evening. Finally, as the sun starts to set, a shape appears along the horizon. Soon, everyone is pointing and squinting as the figure - a man on horseback - comes galloping onto the fort’s parade ground. Slung over his shoulder is a large bag full to the brim with letters.

It is 2026, and the Pony Express rides once again.

For this romantic and nostalgic scene to take place, the patrons of the event need to be kept safe from any sort of adverse weather. Fort Laramie is tremendously exposed to frequent summertime convection, and the National Park Service requested DSS for the great ride this evening. With good reason: by the time shift change occurred at noon MDT, storms were already beginning to develop along the Laramie Range 50 miles to the southwest.

This turned out to be a fascinating case throughout the afternoon - a real “will it or won’t it” as thunderstorms developed and pulsed multiple times over that 50 mile range. The forecasters at Simulated WFO Cheyenne noted increasing lightning potential as early as 1:30 MDT with a much stronger updraft moving off of the terrain. It was initially thought that by 2:30-3:30 MDT, the Fort Laramie area would likely see lightning. However, the storm weakened - a process captured much better by OCTANE Cloud Tops on the Meso band than the CONUS sector.

Figure 1a: Cloud tops from OCTANE over the CONUS sector, showing deepening purples in far southwest Platte County associated with the storm moving toward Fort Laramie.

Figure 1b: Cloud tops from OCTANE over the Mesoscale sector, showing a decrease in the area of purples as the primary thunderstorm collapsed.

Eventually, convection did begin to approach the DSS location. Using a 15-mile range ring, it was unclear whether or not we would breach the event trigger. Two storms developed west of Fort Laramie by about 30 miles and were moving east. The southern storm would undoubtedly track through that 15-mile range ring, but it decayed before arriving. The storm’s final cloud flash occurred about 17 miles away from Fort Laramie proper.

The bigger question, of course, was the updraft on the northwestern flank. If it followed an easterly track, then lightning would assuredly get into the 15-mile range ring. However, a complicated storm splitting process occurred, and regional radar observations (primarily Rapid City radar, scanning at 20,000 feet - the Cheyenne radar is out of commission) suggested that the left split took most of the updraft mass due northward with it. This led to a fascinating case study for LightningCast, where the two MRMS-based V2 products predicted much lower lightning probabilities than the V1 purely satellite-based products, likely due to obfuscation of updraft movement under all of the anvils.

Figure 2: GOES-East (left) and GOES-West (right) LightningCast probabilities at Fort Laramie using the legacy (red) method and the MRMS-included (green) method.

Something to really keep an eye out for when using LightningCast in future IDSS deployments: depending on which product you hitched your wagon to, you could have predicted lightning probabilities of anywhere between 20 and 75% simultaneously. Be careful to use the best data available and blend when possible!

The storms did eventually decay and move off to the north, leaving our hypothetical crowd with a lovely afternoon to enjoy some classic prairie fare, and to prepare for the noble steeds of the Pony Express to ride again.

Sabrina Carpenter