Rio Blanco County, Colorado – Wildfires
On 2 August 2025, two wildfires initiated in Rio Blanco County, located in western Colorado. As of 11 August 2025, the Lee Fire burnt over 116,000 acres with 7% containment. Within the past three days, the fire has rapidly moved to the south towards Garfield County that includes the town of Rifle, Colorado. At the time of this blog entry, the Lee Fire was the 5th largest fire in Colorado state history and is still growing. The second fire, named the Elk Fire, burned over ~14,000 acres and is 30% contained while located east of the Lee Fire. Refer to the Google Map image that shows the approximate fire perimeter extent of both fires on 11 August 2025.
GOES-19 ABI 3.9 um imagery observes the emitted hotspots from both fires (i.e., white and red pixels) throughout the afternoon on 2 August 2025, where clouds (i.e., grey and black pixels that exhibit colder brightness temperatures) also move over the scene.
GOES-19 ABI 3.9um, 5-min temporal resolution, from ~16-02Z, 2 August 2025
After a few days of fire growth, on 5 August 2025, VIIRS observed the fire hotspots, intensities, and smoke from both wildfires. Refer to the VIIRS 4-panel below. Note, the elongated smoke plume, shown distinctly in the VIIRS Visible (0.64 um) and Day Fire RGB imagery that extends ~240 miles eastward towards the Front Range of Colorado. Smoke was also observed along the northern Interstate-25 corridor later that day.
VIIRS 4-Panel –> Top Left: Visible, Top Right: VIIRS Day Fire RGB, Bottom-Left: VIIRS 3.7 um, and Bottom-Right: VIIRS Fire Temperature RGB at 2040Z, on 5 August 2025
A 10-day VIIRS 3.7 um animation shows the evolution of the fires over western Colorado. Notice both fires have an initial rapid fire spread to the east, then the Lee Fire perimeter advances to the south after 8 August 2025. The shortwave infrared imagery is at 375-m, where black pixels indicate the fire hotspots. Notice the white pixels within the fire perimeter as well; this indicates that the VIIRS sensor is saturating, since it’s observing very intense fire pixels. VIIRS exhibits a low saturation temperature of 95C (or 368K), where any fire pixels that are observed above that temperature threshold will produce unrealistic cold pixel anomalies.
VIIRS 3.7um (I4) – Day and Night observations from 2-11 August 2025