1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), GOES-17 Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed 2 distinct pulses of pyrocumulonimbus (pyroCb) cloud emanating from the Cameron Peak Fire in north-central Colorado on 06 September 2020. The coldest cloud-top infrared brightness temperatures were -52.4ºC. Smoke was occasionally restricting the surface visibility to 2 miles at Boulder (KBJC) and 2.5 miles at Fort Collins (KFNL).

This fire also produced a brief pyroCb cloud on the previous day (below), as shown by a single blue (-40ºC) pixel on the 10.35 µm image at 2301 UTC — however, since no Mesoscale Sector was positioned over the area, the fire was only sampled by 5-minute CONUS Sector images. The presence of cloud-top infrared brightness temperatures of -40ºC and colder assures heterogeneous nucleation of all supercooled water droplets to form ice crystals, thereby meeting the criteria of a pyroCb.

===== 07 September Update =====

As the fire continued burning into the nighttime hours, Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images (above) displayed the fire around 0916 UTC or 2:16 am PDT on 07 September. Reflected illumination from the Moon — in the Waning Gibbous phase, at 76% of Full — allowed some of the eastward-drifting smoke to be seen.

A toggle between Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 ABI (3.9 µm) is shown below — the shape of the Cameron Peak Fire thermal anomaly as well as locations of ongoing hot fires along its perimeter were more accurately seen in the 375-m resolution VIIRS image, compared to the 2-km resolution (at satellite sub-point) ABI image. The 2 images are time-matched to correspond to the 0922 UTC time of the Suomi NPP satellite’s overpass.

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), GOES-17 Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed the formation of a pyrocumulonimbus (pyroCb) cloud created by the Creek Fire in Central California on 05 September 2020. The appearance of a few brief GLM FED pixels (2026 UTC | 2117 UTC) indicated that this pyroCb cloud was producing lightning; the coldest cloud-top infrared brightness temperatures were -56.3ºC. The pyroCb developed after the Creek Fire made an explosive run to the north — and the pyroCb also spawned 3 “fire tornadoes”, two of which were rated EF2 and EF1 (SPC Storm Reports | Wildfire Today).

Several hours later, a nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images of the Creek Fire at 0935 UTC or 2:35 am PDT (below) showed the bright glow of the large fire, with several small but very hot fires continuing to burn along its periphery — and a few pyrocumulus clouds were developing along the western/southwestern edge. Along the northeastern edge of the fire signature, outlined in blue, is the Mammoth Pool Reservoir — where over 200 people needed to be airlifted from a campground after the only exit road was cut off by the fast-moving fire (media report).

Scientists believe the pyrocumulonimbus that took shape over the Creek Fire could be the biggest ever produced above U.S. soil.

?: @SweetBrown_Shug https://t.co/PoqFVkKYSy pic.twitter.com/CmMDxh6yU6

— San Francisco Chronicle (@sfchronicle) September 10, 2020

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The animation above shows NOAA-20 VIIRS true color imagery of Pyramid Lake (The Paiute tribe maintains a Pyramid Lake Twitter Account: Link)  in western Nevada. The Lake was closed on 21 July 2020 because cyanotoxins released during a toxic algae bloom (link). The algae bloom is apparent before the lake closure on 21 July, as shown, for example in this Sentinel-2 image.  The color change due to the algal bloom is obvious between 01 and 20 July, as shown below.

The algal bloom was followed by a ‘whiting’ event during which calcium carbonate precipitates into the water (link with description).  On 1 August (below), that suspended calcium carbonate is apparent in far southern Pyramid Lake (Here is an image from 2 August, and here are photographs of the Lake from 5 August).  The discoloration spreads slowly north, covering the entire lake by mid-August.   The animation above shows swirls in both algae and turquoise waters that are related to surface currents in the lake.  The shimmery turquoise color remains as of 3 September 2020.  Check out VIIRS today daily into the future to see how the color changes.

Hat tip to Mike Stavish, SOO at WFO MFR for alerting us to this event!

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the dense smoke plume and thermal anomalies (clusters of yellow to red to black pixels) associated with the SQF Complex of wildfires that had been burning since 24 August. Also evident in the Visible imagery was the presence of brighter white pyrocumulus clouds that persisted for several hours over the source region of one of the hotter fires — in fact, this fire complex included the Castle Fire which produced a pyrocumulonimbus cloud on 23 August.

As the smoke drifted northward across the San Joaquin Valley, surface visibility at some locations such as Fresno (KFAT) was reduced to 5 miles.

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