2 pyrocumulonimbus events in Northern California

September 8th, 2020 |

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

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 over the Hopkins Fire in Northern California on 08 September 2020.

The vertical extent of the pyroCb cloud tower was even more apparent when viewed in Visible imagery from GOES-16 (GOES-East), displayed in the top left panel of the animation below.

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

Later in the day and farther to the east, 1-minute GOES-17 imagery (below) showed the development of another pyroCb cloud over the North  Complex. Unfortunately, there was a ~1-hour gap in images (from 2034 to 2130 UTC) when a yaw flip maneuver was performed on the satellite.

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

However, during this yaw flip maneuver the pyroCb formation and propagation could be followed using 5-minute imagery from GOES-16 (below). As the lower-latitude portion of the smoke plume associated with this fire flare-up drifted south-southwestward, it restricted the surface visibility to 2.5 miles at Beale Air Force Base (KBAB).

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

Fast-moving wildfires in Washington State

September 7th, 2020 |

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), 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 smoke plume and thermal signature of the Pearl Hill Fire — which made a rapid ~50-mile run south-southwestward across northern Washington State on 07 September 2020. During this time, northwesterly winds gusted to 40 knots (46 mph) at Omak (KOMK) near the source of the fire. Downwind of the fire, smoke reduced the visibility to 1.5 miles at times in Wenatchee (KEAT).

Later in the day, smaller fires which started burning farther to the east exhibited similar (albeit much shorter-distance) southwestward runs.

Pyrocumulonimbus clouds produced by the Cameron Peak Fire in Colorado

September 6th, 2020 |

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

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.

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

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

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images, with plots of METAR surface reports [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images, with plots of METAR surface reports [click to enlarge]

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.

Shortwave Infrared images from Suomi NPP (3.74 µm) and GOES-16 (3.9 µm), with plots of METAR surface reports [click to enlarge]

Shortwave Infrared images from Suomi NPP (3.74 µm) and GOES-16 (3.9 µm), with plots of METAR surface reports [click to enlarge]

SQF Complex fires in California

September 3rd, 2020 |

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

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.