An explosion followed by a large fire occurred at the Chevron El Segundo refinery near Los Angeles (media story) around 0430 UTC on 03 October 2025 (9:30 PM PDT on 02 October). A thermal signature of the fire was evident in 5-minute CONUS Sector GOES-18 (GOES-West) Near-Infrared and Shortwave Infrared images (above), beginning at 0431 UTC — however, this thermal signature began to become less apparent after about 0701 UTC.

In contrast, GOES-18 Microphysics RGB images with an overlay of Next Generation Fire System (NGFS) Fire Detection polygons (below) exhibited a distinct thermal signature for a significantly longer time period (ending at 1626 UTC).

A cursor sample of GOES-18 NGFS Fire Detection parameters at 0431 UTC is shown below.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed Hurricane Imelda as it intensified from a Category 1 to a Category 2 storm (at 1800 UTC) while approaching Bermuda on 01 October 2025. GLM Flash Points revealed very little satellite-detected lightning activity within the eyewall of Imelda.

About an hour prior to the beginning of the GOES-19 Visible/Infrared image animation above, a DMSP-17 SSMIS Microwave image at 1057 UTC (below) depicted the eye and eyewall of Imelda.

After sunset, 1-minute GOES-19 Infrared images (below) showed Imelda as it moved across the island of Bermuda. The strongest wind gust at Bermuda/Wade International Airport (TXKF) was on the back side of Imelda, with 49 kts occurring at 0400 UTC. Soon after the core of Imelda passed over Bermuda, a series of convective bursts exhibited cloud-top infrared brightness temperatures as cold as -87ºC. Interestingly, brief clusters of GLM Flash Points were associated with some of these convective bursts northeast of Bermuda — until that point, there was a general void of lighting activity with Imelda after sunset.

According to a plot of rawinsonde data from Bermuda International Airport (below), the coldest cloud-top infrared brightness temperature of -87ºC corresponded to an overshoot of the Most Unstable (MU) air parcel’s Equilibrium Level (EL) of at least 1 km.

Category 2 Imelda moved across a patch of warmer Sea Surface Temperature and higher Ocean Heat Content as it approached Bermuda (below) — that warmer water could have played a role in fueling the development of the aforementioned convective bursts (with lighting activity) seen in GOES-19 Infrared imagery.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible images (above) showed Hurricane Humberto as it intensified from a Category 4 to a Category 5 storm on 27 September 2025 (Humberto became the second Category 5 storm in the Atlantic Basin this season — with Erin being the first). Low-altitude mesovortices were evident within the eye, along with cloud-top gravity waves in the surrounding eyewall region.

In an animation of 1-minute GOES-19 Infrared images (below), the eye began to exhibit a slight amount of trochoidal motion as Humberto intensified later in the day.

A DMSP-18 SSMIS Microwave image at 2013 UTC — shortly before Humberto was upgraded to Category 5 at 2100 UTC (below) displayed a fully-closed inner eyewall.

Humberto’s intensification to Category 5 occurred as the hurricane was moving through an environment of weak deep-layer wind shear (below) and traversing warm water.

Microwave, wind shear and sea surface temperature imagery was sourced from the CIMSS Tropical Cyclones site.

A RCM-2 Synthetic Aperture Radar (SAR) image (source) at 2214 UTC (below) sensed wind speeds as high as 126.94 kt in the NW quadrant of Humberto.

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10-minute Full Disk scan GOES-18 (GOES-West) daytime True Color RGB + nighttime Dust RGB images created using Geo2Grid (above) showed a plume of resuspended volcanic ash (hazy shades of tan in True Color RGB, and shades of violet in Dust RGB) from the 1912 Novarupta-Katmai eruption in Alaska — which was being transported offshore across the Shelikof Strait and over parts of Kodiak Island during 22-23 September 2025. Surface volcanic ash within the Valley Of Ten Thousand Smokes was being lofted by strong northwesterly winds that were being channeled through the valley.

According to this USGS Volcano Notice, the National Weather Service issued a SIGMET advising aviation interests that the maximum height of this resuspended ash was 6000 ft.

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