This is a cumulonimbus cloud just west of Horsetooth Reservoir in Fort Collins at 4 pm on Sept 19th, 2026. The skew-T plot is from Grand Junction at midnight GMT on Sept 20th, 2026, which is the closest plot to the actual time. The clouds start around 3150 m, and the atmosphere is unstable. Cumulonimbus clouds occur in unstable atmospheres and extend from around 1600 m to the troposphere. During this hike, we got rained on, and there was lots of lightning and thunder. The report is attached here, and the original image is shown below.