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Wildfires produce pyrocumulonimbus clouds in Alaska

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Clean” Infrared Window (10.3 µm) images and “Red” Visible (0.64 µm) images with an overlay of the FDCA Fire Mask derived product (above) showed that a wildfire southwest of Nenana, Alaska (METAR site PANN) produced two pyrocumulonimbus (pyroCb) clouds late in the day on... Read More

1-minute GOES-18 Clean Infrared Window (10.3 µm, left) images and Red Visible (0.64 µm) images with an overlay of the Fire Mask derived product (right), from 2301 UTC on 20 June to 0400 UTC on 21 June [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Clean” Infrared Window (10.3 µm) images and “Red” Visible (0.64 µm) images with an overlay of the FDCA Fire Mask derived product (above) showed that a wildfire southwest of Nenana, Alaska (METAR site PANN) produced two pyrocumulonimbus (pyroCb) clouds late in the day on 20 June 2025 . The pyroCb clouds exhibited cloud-top 10.3 µm infrared brightness temperatures (IRBTs) in the -40s C (denoted by shades of blue to cyan) — a necessary condition to be classified as a pyroCb — with the first pyroCb developing at 0027 UTC on 21 June, and the second pyroCb forming at 0226 UTC. These were the first confirmed pyroCbs in Alaska for the 2025 wildfire season.

Another wildfire just east of Healy Lake, Alaska later produced a larger pyroCb, developing at 0326 UTC (below).

1-minute GOES-18 Clean Infrared Window (10.3 µm, left) images and Red Visible (0.64 µm) images with an overlay of the Fire Mask derived product (right), from 0100-0700 UTC on 21 June [click to play MP4 animation]

The coldest cloud-top IRBT exhibited by the Healy Lake pyroCb was -57.12 C at 0607 UTC (below) — colder than the -43.66 C and -49.01 C IRBTs for the two pyroCbs produced by the wildfire southwest of Nenana.

GOES-18 Clean Infrared Window (10.3 µm, left) image and Red Visible (0.64 µm) image + Fire Mask derived product (right) at 0607 UTC on 21 June, with a cursor sample of the coldest pyroCb cloud-top infrared brightness temperature [click to enlarge]

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Hurricane Erick makes landfall along the Pacific coast of Mexico

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed Hurricane Erick as it intensified from a Category 2 storm at 1800 UTC on 18 June to a Category 3 storm by 0000 UTC on 19 June 2025. The eye became a bit more defined during that time period... Read More

1-minute GOES-19 Visible (0.64 µm) and Infrared (10.3 µm) images, from 1800 UTC on 18 June to 0053 UTC on 19 June [click to play animated GIF]

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed Hurricane Erick as it intensified from a Category 2 storm at 1800 UTC on 18 June to a Category 3 storm by 0000 UTC on 19 June 2025. The eye became a bit more defined during that time period — and convective bursts within the eyewall occasionally exhibited cloud-top infrared brightness temperatures of -80ºC or colder (violet pixels embedded within brighter white regions).

Erick was moving through an environment characterized by low values of deep-layer wind shear (below) — a factor that favored further intensification.

GOES-19 Infrared images, with an overlay of deep-layer wind shear at 0000 UTC on 19 June

A DMSP-18 Microwave image at 2154 UTC on 18 June (below) displayed a large outer eyewall (and hints of a partial inner eyewall), suggesting that an eyewall replacement cycle might soon occur.

DMSP-18 SSMI/S Microwave (85 GHz) image at 2154 UTC on 18 June [click to enlarge]

1-minute GOES-19 Infrared images (below) showed the period where Erick continued its rapid intensification, becoming a Category 4 storm just before 0600 UTC on 19 June. The hurricane weakened somewhat to Category 3 intensity shortly before making landfall in far western Oaxaca, Mexico around 1200 UTC on 19 June (and the eye became ill-defined closer to the time of landfall). Convective bursts west of the eyewall occasionally reached -90ºC (yellow pixels embedded within darker purple areas).

1-minute GOES-19 Infrared (10.3 µm) images, from 2100 UTC on 18 June to 1301 UTC on 19 June [click to play animated GIF]

Deep-layer wind shear remained very low in the vicinity of Erick (below), maintaining a favorable environment for intensification — and the hurricane also traversed very warm Sea Surface Temperatures during its period of rapid intensification.

GOES-19 Infrared images, with an overlay of deep-layer wind shear at 0900 UTC on 19 June

A DMSP-18 Microwave image at 1030 UTC on 19 June (below) suggested that landfall might have occurred a bit earlier than 1200 UTC.

DMSP-18 SSMI/S Microwave (85 GHz) image at 1030 UTC on 19 June [click to enlarge]

Deep-later wind shear, DMSP and Sea Surface Temperature images were sourced from the CIMSS Tropical Cyclones site.

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Explosion of SpaceX Starship at the Starbase launch facility in Texas

By Scott Bachmeier •

5-minute CONUS Sector GOES-19 (GOES-East) Near-Infrared and Shortwave Infrared images (above) showed thermal signatures of an explosion of SpaceX Starship at the Starbase launch facility in South Texas that occurred at 0401 UTC on 19 June or 11:01 PM CDT on 18 June 2025 (NASASpaceflight.com article).The resulting large fire was hot... Read More

5-minute GOES-19 Near-Infrared (0.87 µm, 1.61 µm and 2.25 µm) and Shortwave Infrared (3.9 µm) images, from 0356-0426 UTC on 19 June [click to play MP4 animation]

5-minute CONUS Sector GOES-19 (GOES-East) Near-Infrared and Shortwave Infrared images (above) showed thermal signatures of an explosion of SpaceX Starship at the Starbase launch facility in South Texas that occurred at 0401 UTC on 19 June or 11:01 PM CDT on 18 June 2025 (NASASpaceflight.com article).

The resulting large fire was hot enough to be flagged as a Processed Fire by the GOES-19 Fire Detection and Characterization Algorithm (FDCA), with a Fire Power value of 46.85 MW at 0401 UTC (below).

GOES-19 Near-Infrared (0.87 µm, 1.61 µm and 2.25 µm) and Shortwave Infrared (3.9 µm) images with an overlay (and cursor sample) of the FDCA Fire Power and Fire Mask at 0401 UTC on 19 June [click to enlarge]

The Next Generation Fire System (NGFS) also displayed GOES-19 Fire Detection polygons (below) — beginning at 0401 UTC, the time of the Starship explosion.

5-minute GOES-19 Microphysics RGB images with an overlay of NGFS Fire Detection polygons, from 0356-0426 UTC on 19 June [click to play MP4 animation]

A cursor probe of a GOES-19 NGFS Fire Detection pixel at 0401 UTC is shown below.

GOES-19 Microphysics RGB image with a cursor probe of a NGFS Fire Detection pixel at 0406 UTC on 19 June [click to enlarge]

In spite of its larger satellite viewing angle and less frequent 10-minute Full Disk scans over Texas, a distinct thermal signature (darker blue pixels) was still seen in a GOES-18 (GOES-West) Microphysics RGB image at 0400 UTC (below).

10-minute GOES-18 Microphysics RGB images, from 0350-0430 UTC on 19 June [click to play MP4 animation]

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Eruption of Lewotobi Laki-laki in Indonesia

By Scott Bachmeier •

The Lewotobi Laki-laki volcano in Indonesia erupted at 0935 UTC on 17 June 2025 — and the radiometrically-retrieved Ash Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site (above) indicated that some of the volcanic ash reached altitudes around 16.2 km (a 1645 UTC Darwin VAAC advisory listed ash to altitudes of FL530 or 53000 ft).The... Read More

Himawari-9 Ash Height product [click to play MP4 animation]

The Lewotobi Laki-laki volcano in Indonesia erupted at 0935 UTC on 17 June 2025 — and the radiometrically-retrieved Ash Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site (above) indicated that some of the volcanic ash reached altitudes around 16.2 km (a 1645 UTC Darwin VAAC advisory listed ash to altitudes of FL530 or 53000 ft).

The corresponding Ash Loading product (below) showed that initially there were high levels of ash loading, which then decreased in time as the volcanic cloud expanded across the region.

Himawari-9 Ash Loading product [click to play MP4 animation]

Himawari-9 Ash RGB images created using Geo2Grid (below) revealed that the volcanic cloud was composed of either primarily ash (shades of red), a mixture of ash and SO2 (shades of yellow) or primarily SO2 (shades of light green).

Himawari-9 Ash RGB images [click to play animated GIF | MP4]

In a NOAA-20 VIIRS Day/Night Band image after sunset (below), the bright nighttime glow of the summit of still-erupting Lewotobi was very apparent — and a subtle hazy signature of the volcanic cloud (northwest, west and southwest of Lewotobi) was also evident.

NOAA-20 (mislabeled as NPP) VIIRS Day/Night Band image valid at 1647 UTC or 11:37 PM local time on 17 June [click to enlarge]

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