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
