Overview: Week 3, Day 2

10 AM

Tuesday began with our morning discussion from Monday's operation/orientation day. Forecasters had plenty of storms to observe yesterday, which allowed everyone to get acquainted with OCTANE. Forecasters talked about the applications of OCTANE data, and one said it can be a 'super tool' for mesoanalysis but also needs 'super users'. For the Synthetic GXI WVT product, forecasters also showed early support for the 'flipped' color table but wanted to see it in action more this week before deciding. First impressions of the Lightning Stoplight and SZA Imagery were also positive, with forecasters finding the Stoplight tool easy to understand and message to partners.

I showed an example of some SZA imagery on CIRA-SLIDER from this morning of river valley fog in the Northeast US. When comparing with traditional imagery and the Nighttime Microphysics RGB, forecasters reacted positively to the 'brighter' SZA imagery and expressed the difficulties of transitioning from day to night when observing fog from their respective home CWAs.

SZA Day Cloud Phase Distinction RGB

Regular Day Cloud Phase Distinction RGB

Nighttime Microphysics RGB

After talking about the GeoXO GXI in our focus group, our forecast discussion for the day sent us back to the Cheyenne, WY (CYS) and Rapid City, SD (UNR) NWS offices to monitor developing storms along a cold front. Forecasters were also assigned mock-IDSS events in Fort Laramie, WY and Sturgis, SD.

1 PM

Similar to Monday, shortly after operations began SPC issued an MD for our area followed by a Severe Thunderstorm Watch.

In the CYS office (still without a radar), discussion focused on their mock-IDSS event and the timing of lightning activity within the event's range ring. With thunderstorms developing upstream of the site, timing dominated the conversation and the forecasters talked about how the LightningCast dashboard helped identify trends, especially if the partner needed more time to execute their safety plans.

The forecasters also looked at OCTANE, and noted that the the MESO Cloud-Top Cooling products showed a decreasing intensity trend while the CONUS CTC product appeared relatively steady.

3PM

The UNR office frequently viewed OCTANE products today, with several severe thunderstorm warnings issued today. Their mock-IDSS site appeared to 'miss' the storms today, but we'll see what they say tomorrow!

I plan to show this to the forecasters tomorrow to get their thoughts. Sorry for spamming the blog with SZA imagery.

-Kevin

Orographic Thunderstorms and Downbursts over Southeastern Wyoming

 Convective Initiation (1900 UTC)

The afternoon of 1 June 2026 has been convectively productive over and east of the Rocky Mountain Front Range of Wyoming and Colorado. The 1900 UTC composite satellite image in Figure 1 below captures the early afternoon development of a complex of strong, orographically-forced and high-based thunderstorms. These cells initially fired over the Rocky Mountain Front Range of southeastern Wyoming. As the system advected east-northeastward, satellite and MRMS data indicated rapid storm intensification, characterized by sharply cooling, ice-phase cloud tops and a significant surge in lightning flash rates. 

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

Linear Organization & Downburst Signatures (2006 UTC)

By 2006 UTC, the convection underwent a clear structural evolution into a downburst-producing thunderstorm system. The previously disorganized multicell clusters organized into a short-segment linear complex. Key Feature: The satellite presentation highlights a prominent rear-flank dry-air notch, which is a classic morphological signature of severe downburst potential as mid-level dry air is entrained into the storm's downdraft. Surface Observation: Validating this remote sensing presentation, a severe 52-knot downburst wind gust was recorded at the surface in Bordeaux, WY, at 1958 UTC, just minutes before this satellite scan.

Figure 2. Composite SZA cloud phase distinction, MRMS reflectivity, and LightningCast probability product image at 2006 UTC 1 June 2026.

Figure 3. Comparison between the GOES-19 (G19) sounding retrieval and the Rapid Refresh (RAP) model sounding at 1800 UTC 1 June 2026.

Thermodynamic Environment: Cheyenne Soundings (1800 UTC)

To understand the atmospheric mechanics driving these downbursts, we can analyze the 1800 UTC thermodynamic environment over Cheyenne, WY in Figures 3 and 4. A comparison between the GOES-19 (G19) sounding retrieval and the Rapid Refresh (RAP) model sounding reveals a prominent "hourglass-inverted-V" profile in the lower and mid-troposphere—a textbook thermodynamic setup for evaporatively cooled, severe convective wind gusts.

The associated Wind Gust Potential (WGP) derived from these profiles showed values ranging from 39.2 knots (G19) to 44.5 knots (RAP), which closely aligns with the observed severe gusts in the region.

Regional Corroboration: Denver ACARS Profile (1647 UTC)

Further corroborating the regional environmental setup is an ACARS vertical sounding profile retrieved at 1647 UTC from Denver, CO  (Denver International Airport). When compared to the Cheyenne RAP model sounding, the Denver ACARS data demonstrates excellent structural agreement across the Front Range boundary layer. Specifically, the profile highlights highly favorable wet-bulb zero heights and substantial Downdraft CAPE (DCAPE), confirming a widespread optimal thermodynamic environment for the robust downburst generation observed throughout the afternoon.

Figure 4. Comparison between the Denver, CO ACARS sounding profile at 1647 UTC and the Cheyenne, WY Rapid Refresh (RAP) model sounding at 1800 UTC 1 June 2026.

StormRangerWX

Dry Signals in Synthetic GeoXO

Today’s setup featured a typical high plains return flow pattern with low-level moisture upslope evident on surface observations and both the synthetic WVT & 5.15um channel imagery. One feature that caught my attention initially in the synthetic imagery was a dry pool over the Cheyenne Ridge, spanning from Weld County, CO up into Kimball County, NE (highlighted with yellow circle in the image below).  Observed surface dew points in this area were in the mid to upper 40s in southeasterly flow, likely on the leading edge of the plume of higher moisture in KS and CO. I did not see this level of detail on any other satellite imagery.

With this feature, I was curious on two fronts: the placement of this feature compared to reality, but also how would this dry pool affect convection later in the day. Compared with surface obs, the dry pool seemed to be slightly displaced to the east from reality, but not by far.  My gut was telling me that convective initiation on the Cheyenne Ridge itself would be nil due to the dry pool (perhaps with a hint of subsidence?), and that any established convection moving through the drier air would not exhibit explosive growth and would overall be weaker, and/or perhaps we’d see an enhanced downdraft wind threat. 

See below the loop of synthetic imagery highlighting the 5.15um imagery that covered the majority of our test period. Reality played out pretty close to the evolution of convection as seen in the loop. A left split fired off the mountains near Fort Collins and persisted northeast up into Wyoming. This storm produced severe hail slightly larger than quarter size in Cheyenne, but then appeared to weaken on visible satellite as it progressed further east-northeast along the Cheyenne Ridge where the drier air was forecast to reside.

This case shows the utility of highlighting moisture content, or lack thereof, that you cannot necessarily see on traditional satellite imagery.

Astrophage

Initial Impressions

 

Very impressed with the Octane CTC product. This loop is probably a bit too fast. But It captured and area of rapid cooling east of Perry Park

At that time radar was not picking up on much at all.

20 minutes later the cell really took off with a deep core of over 60dbz reaching above -20C (panel in the top right)

While the storm was pretty vertically stacked there low ZDR and lack of melting near the surface likely lead to hail production. The fact that the CTC ID’d the area before any signal on the radar is very impressive.

The other thing that caught my eye today was the WVT Ratio. After playing around with the color map ranges I was able to tease out the moisture feed streaming into the Front Range. Overlaying this with observations matches the overall surface streamlines well. Would be very interested to see this in a dry line set up.

IsthataTOR

BOU Octane Cloud Top Cooling Observations

Day 1: GOES-19 CONUS Octane Cloud Top Cooling proved itself to be a very helpful tool for diagnosing deep CI attempts along the front range of the Colorado Rockies. It was interesting to see several failed attempts at CI when the colors turned from green back to cyan. I found it to be an excellent RGB for situational awareness in the pre-storm environment. It was nice to quickly diagnose updraft strength as well. Pairing it with the 5 minute CG Flash ENTLN 1 minute update lightning plot helped me quickly visualize the parallax effect on GOES-19 where you have to mentally adjust where the actual storm to the southeast. Using just those 2 datasets alone, I tried to draw a couple of severe thunderstorm warnings. The boxes were most likely bigger than what was actually issued since I was playing it safe including most of the lightning within the back end of the box. I liked how the CTC product did not show any colors above 0C to tease out surface level features. It looks like there was some sort of mesoscale boundary that moved into the southern part of the Denver metro that led to additional CI. I would not have picked out that boundary as easily if the CTC product had colors through 30C for example.

Figure 1: Convection initiation and intensification over the Denver metropolitan area using GOES 19 ECONUS Octane Cloud Top Cooling imagery.

WXMANDAN

A High-OCTANE Way to Start the HWT

 The first day of our Satellite HWT threw us up against the ultimate satellite forecasting challenge - how to analyze severe convection while the local radar is out of service. Specifically, KCYS is out of commission this afternoon while convection is developing off of the Laramie Range.

This presents an interesting challenge for the newest version of LightningCast. LightningCast V1 is a purely satellite-based product that uses four different satellite channels to determine the likelihood of an updraft producing lightning in the next 60 minutes. We’re here this week in part to test Version 2, which uses those same methods but is also trained on several years worth of MRMS isothermal reflectivity at the -10C level. Here’s the issue, though: if KCYS is out of commission, then the closest radar (KFTG) is shooting at 21,000 feet for the 0.5 degree reflectivity scan over Wheatland, Wyoming!

With that in mind, here’s the legacy LightningCast (left panel) vs LightningCast V2 (right panel) as an updraft developed off of the Laramie Range today.

Figure 1: LightningCast probabilities valid at 18:16 UTC on June 1, 2026

Notably, the first lightning strikes came in about 15-20 minutes after the above screenshot. The MRMS-based LightningCast was, if anything, a little more conservative than its no-radar ancestor. It also was struggling to display any reflectivity. You never want to infer a causal relationship based off of one case, but it wouldn’t surprise me if the two are connected.

In another exciting introduction to satellite-based mesoanalysis tools, we got a good look at OCTANE speed/direction tools, which allow us to directly measure the motion of cloud layers that may not be accessible to satellite (eg, the anvil). Below, we are looking at a cluster of severe thunderstorms near Chugwater, Wyoming.

Figure 2: OCTANE Direction product on June 1, 2026

The sharp gradient in greens and oranges is suggestive of divergence within the thunderstorm anvil region - which we would expect to see in an updraft that is evacuating mass toward the tropopause. Even more interestingly, one can see the arced band of inflow clouds/HCRs extending well back into western Nebraska, not just as they feed into the storms, but also as they are literally bent inward by the pressure perturbations. The red hues to the feeder clouds in Nebraska is suggestive of a motion from the southeast, while closer to Chugwater those feeder clouds moved more from the south. We thus know that the thunderstorms are exhibiting a mesoscale influence on their environment.

-Sabrina Carpenter

Rapid cooling visible with developing supercells.

 Scattered to widespread severe thunderstorms were shown to be developing from Fort Collins south and through the Denver metropolitan area. When overlaid with other products, I noticed how LightningCast v2 was able to catch on to some of these rapidly cooling cloud tops faster than v1. The contrast of the strong convection vs weak was very helpful in determining which cells were going to become severe or not as well as which mature supercells were maintaining strength or weakening.

Fig 1. Rapidly cooling cloud tops and several mature supercells shown developing across the Denver metro.

Cloudius

Overview: Week 3, Day 1

 Week 3 kicks off today and the ridge that stymied us in week two is....still there! Thankfully we've recovered a good bit of moisture across the plains and southeast for convection to work with. We began today with product introductions and an orientation session, followed by our forecast discussion to decide where we would target today. The forecast was pretty clean cut, with two options of elevated convection in NE Colorado/SE Wyoming and additional convection from a remnant MCS across Mississippi/Arkansas. Based on timing of CI, instability in the high plains, and the size of the MesoAnywhere domain, we decided to localized to the NWS offices of Cheyenne, WY (CYS) and Boulder, CO (BOU).

1 PM

SPC issued an MD just before operations began for our area, citing thunderstorm development and a high chance for a watch to be issued later. And by 2pm we had a watch!

 

In the CYS office, forecasters looked at synthetic GXI imagery and identifying the moisture advection northward into their CWA later in the forecast period. This also led to the discovery that a few of the procedures had 'inverted' color maps for WVT. While not intended, we did compare how they looked from each color map. Which is better? You decide!

Original colormap. Dry air/clouds are white, moisture is dark.

'Flipped' color map. Dry air/clouds are black, moisture is light.

First impressions of SZA from this morning's imagery was positive with forecasters in both the CYS and BOU offices. A forecaster with experience in AK said they regularly adjust brightness of visible imagery on the fly, especially in lower light seasons. A forecaster with more experience in the central plains said they rarely adjust the brightness. Some of the areas we examined included over Colorado and Montana. Forecasters mentioned using the DCPD RGB frequently, and having more time with that imagery would be welcome. Additionally, one mentioned liking that the colors stayed more consistent throughout the day.

Forecasters in the CYS office compared LightningCast v1 and v2 from GOES-East and GOES-West along with the timing of the first lightning flash. V2 introduced more heterogenety in the bands, while V1 appeared fairly uniofrm and more widespread. Also LightningCast v2 seemed to be ahead of v1 for thunderstorm growth over the Denver metro.

3 PM

Both offices issued severe thunderstorm warnings for severe wind and hail hazards. Looking ahead, we have a steady stream of SLGTs this week, so we should stay fairly active. Also wanted to noted the CYS radar was out today, so some questions about using Sat data (especially things like OCTANE) for warnings are of interest for the morning discussion tomorrow.

-Kevin

Monitoring Downburst-Producing Thunderstorm Development in Southwestern Kansas

 Convective Initiation and Multi-Sensor Signatures

Our analysis begins with a compelling multi-sensor perspective of a vigorous, multicellular, high-based thunderstorm cluster rapidly organizing over southwestern Kansas as depicted in Figure 1. By analyzing a composite of the GOES-19 Cloud Phase Distinction product, LightningCast probabilities, and MRMS base reflectivity, several severe storm signatures become immediately evident. The imagery highlights expansive, cold ice-bearing cloud tops and high localized reflectivity cores, which are strongly correlated with high lightning probabilities. Together, these features highlight an environment highly favorable for robust precipitation loading and subsequent severe downburst generation, specifically targeting the communities of Liberal and Meade, Kansas.

Figure 1: Composite image of GOES-19 SZA Day Cloud Phase Distinction, LightningCast lightning probability, and MRMS radar reflectivity at 1951 UTC 14 May 2026.

Cloud Convection and Downburst Validation

Building upon the initial analysis, the Figure 2 shifts focus to a composite view utilizing the GOES-19 Cloud Convection product alongside LightningCast and MRMS reflectivity. This specific combination provides a clear view of the intense convective cores and robust updrafts associated with the cluster. The impressive convective depth and structural characteristics identified in this imagery directly foreshadowed the surface wind impacts. Validating these satellite and radar signatures, sub-severe downburst wind gusts were recorded shortly near 2000 UTC, with a 44-knot gust observed at Liberal, KS, and a 47-knot gust recorded at Meade, KS.

Figure 2: Composite image of GOES-19 SZA Day Cloud Convection, LightningCast lightning probability, and MRMS radar reflectivity at 2001 UTC 14 May 2026.

Thermodynamic Analysis (GOES-19 & RAP Model)

To understand the thermodynamic drivers behind these severe downbursts, we evaluate the 1900 UTC sounding profiles near Liberal, Kansas. A comparison between GOES-19 derived soundings and the RAP model output in Figure 3 reveals excellent agreement, with both platforms depicting a classic 'inverted-V' thermodynamic profile. This signature, characterized by a deep, dry sub-cloud layer beneath a moist convective layer, is a textbook indicator for evaporatively generated downbursts. Additionally, both profiles show wet-bulb zero heights near the 650-mb level. The integration of these parameters via the Microburst Windspeed Potential Index (MWPI) yielded a calculated Wind Gust Potential (WGP) of 60 to 64 knots, accurately emphasizing the high downburst wind threat.

Figure 3. GOES-19 and RAP model sounding profiles retrieved near Liberal, KS at 1900 UTC 14 May 2026.

Observational Ground-Truth (Dodge City RAOB)

Further solidifying the thermodynamic assessment, the 1800 UTC radiosonde observation (RAOB) launched from nearby Dodge City, Kansas, and shown in Figure 4, serves as critical observational ground-truth. The RAOB data supports the signatures identified in the GOES-19 and RAP model soundings from Figure 3. Featuring the same pronounced inverted-V profile and substantial sub-cloud dry air, the Dodge City sounding confirmed that the regional atmospheric environment across southwestern Kansas was broadly primed for high-based convection and efficient, momentum transfer and severe downburst wind generation.

Figure 4. RAOB sounding profile retrieved at Dodge City, KS at 1800 UTC 14 May 2026.

-StormRangerWX

Dry Signal East of Developing Dry Line?

 An interesting signal developed in the GeoXO synthetic Water Vapor Transmittance (WVT) imagery today across Texas. Higher reflectance values (brighter colors in the WVT) were sandwiched between lower values, both to the west and east, in Central TX.

Figure 1: 4-panel with GeoXO synthetic imagery (5.15 band - top left, WVT - top right) and GOES-19 imagery (IR - bottom left, VIS - bottom right) at ~1800 UTC 14 May 2026.

At first, this signal seemed a bit counterintuitive, as the dry line was expected to develop in western TX, based on today’s briefing and the SPC Convective Outlook. However, when taking a look at the Advected Layered Precipitable Water (ALPW) product at nearly the same time (1800 UTC 14 May 2026), there’s noticeably higher moisture in the 850-700 and 700-500 hPa layers across West TX and New Mexico, and to the east near the TX/LA border.

Figure 2: 4-panel CIRA ALPW at 1800 UTC 14 May 2026.

A 1700 UTC HRRR forecast run, valid for 1800 UTC, just southeast of the TX Panhandle, showed this sharp reduction in moisture in its sounding near 850 hPa. Farther west, this sharp reduction is not evident. Perhaps the dry air around 850 hPa resulted in this counterintuitive WVT signal in TX.

Figure 3: HRRR sounding over North-Central TX at 1800 UTC 14 May 2026.

Figure 4: HRRR sounding over the Texas Panhandle at 1800 UTC 14 May 2026.

-csmith70