10-minute Full Disk scan GOES-18 (GOES-West) “Red” Visible (0.64 µm) images with an overlay of the Fire Mask derived product (a component of the GOES Fire Detection and Characterization Algorithm FDCA) and “Clean” Infrared Window (10.3 µm) images (above) showed 2 pulses of pyrocumulonimbus (pyroCb) clouds — exhibiting cloud-top infrared brightness temperatures in the -40s to -50s C, denoted by shades of blue to red in the 10.3 µm images — that were produced by the McDonald Fire (located just southeast of Fairbanks, Alaska) late in the day on 17 June 2024. As they moved eastward toward the Alaska/Yukon border, the first pyroCb reached a minimum cloud-top infrared brightness temperature of -53.7ºC, with the second pyroCb later reaching -54.4ºC.

A Suomi-NPP Infrared Window (11.45 µm) image valid at 2319 UTC on 17 June (below) captured the first pyroCb cloud not long after its formation — and included a cursor sample of cloud-top brightness temperatures for both the 11.45 µm (-55.58ºC) and the underlying 3.74 µm Shortwave Infrared image (+25.10ºC).  During the daytime, pyroCb cloud tops will usually exhibit significantly warmer Shortwave Infrared brightness temperatures, due to enhanced reflection of solar radiation off the smaller ice crystals found in the pyroCb anvil (reference).

A Landsat-9 Natural Color RGB image displayed using RealEarth (below) depicted the areal extent of the McDonald Fire burn scar (darker shades of brown) at 2105 UTC on 17 June, just prior to the flare-up of the wildfire that produced the 2 pyroCb clouds.

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One of the products demonstrated at the Hazardous Weather Testbed (HWT) in Norman in May and June this year was GREMLIN (GOES Radar Estimation via Machine Learning to Inform NWP) a tool created with Machine Learning (by Kyle Hilburn at CIRA) to use ABI and GLM data to create synthetic radar reflectivity fields. (This article describes the product fully). GREMLIN was trained on GOES-16 CONUS data, but in these images it is displayed over American Samoa (the product has been incorporated into the AWIPS machine at WSO Pago Pago), and it’s being compared to hourly estimates of rainfall from CMORPH-2. The images below show 6 fields (at 10-minute intervals) of simulated radar and an hourly CMORPH-2 accumulation derived independently and displayed in RealEarth.

Consider the 15 different animations shown below, that step through an event with rain over the Samoan Islands. In general, the CMORPH-2 hourly accumulations on the right agree in general with where the radar estimates derived from GREMLIN suggest rain might be falling.

What should a user do when GREMLIN does or does not show rain where CMORPH-2 is or is not showing rain accumulation. It should not make a user think “Oh, this is wrong”; rather, it means a user should investigate those regions using other satellite imagery to determine whether or not rains are occurring.

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1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Day Fire RGB, Shortwave Infrared (3.9 µm), and “Red” Visible (0.64 µm) images with overlays of the Fire Power and Fire Mask derived product (2 components of the GOES Fire Detection and Characterization Algorithm FDCA) (above) displayed signatures of the Post Fire, which reportedly started around 2052 UTC on 15 June 2024 near Gorman, California (in far northwest Los Angeles County). The initial GOES-18 fire detection occurred at 2104 UTC — and the 3.9 µm Shortwave Infrared brightness temperature first reached 137.88ºC (the saturation temperature of GOES-18 ABI Band 7 detectors) at 2216 UTC. The wildfire caused evacuations to be ordered for areas just west of Interstate 5.

1-minute GOES-18 True Color RGB images (source) from 2130 UTC on 15 June to 0149 UTC on 16 June (below) showed the transport of dense smoke from the wildfire. Note the occasional pyrocumulus jumps near the fire source region.

1-minute GOES-18 Day Fire RGB images (below) included plots of METAR surface reporting sites. Although the smoke plume  passed directly over KSDB and KWJF, the bulk of the smoke remained aloft (at altitudes between 2000-8000 ft, therefore casting a shadow onto the ground below) and did not significantly reduce the surface visibility at either site.

A NOAA-21 VIIRS Day/Night Band image valid at 0944 UTC (2:44 AM local time) on 16 June (below) displayed the bright nighttime glow of the Post Fire (between Gorman and Pyramid Lake).

A 27-hour animation of 1-minute GOES-18 Shortwave Infrared (3.9 µm) images (below) showed the diurnal behavior of the Post Fire thermal signature as it continued to burn south-southeastward along the Interstate 5 corridor.

In a toggle between NOAA-20 VIIRS True Color and False Color RGB images (source) at 2014 UTC on 16 June (below), the Post Fire burn scar appeared as shades of gray to reddish-orange — while an active fire front along the southern edge (from which a smoke plume was emanating) exhibited brighter shades of pink.

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GOES-18 imagery over California at 1836 UTC (above, left) show a very strong signal over San Luis Obispo County: very bright in visible imagery and warm in the shortwave infrared. In the GOES-16 imagery, that signal is not present. In contrast, the warm signal in the shortwave infrared in GOES-18 imagery below has a similar signal in the GOES-16 imagery. (Click here for a shortwave infrared animation from GOES-16 animation, and here from GOES-18). In the imagery above, the lack of a signal in GOES-16 might mean this is an example of reflection off solar panels In contrast, imagery below suggests a fire is present, as the detection is present in shortwave infrared imagery from both satellites.

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The Next Generation Fire System (NGFS) is a NOAA/NESDIS initiative to streamline the detection of fires as soon as they occur. The NGFS Alerts Dashboard (Documentation on the NGFS is here) shows the results of continuous automatic monitoring of satellite data for the development of hot spots such as those seen in the still images and animations above. What kind of information was available for the two events above, one a result of reflection off solar panels, and one a result of a fire? NGFS output at 1831 (Microphysics RGB) and 1836 UTC (Fire Temperature RGB and Visible imagery) is shown below.

The NGFS report allows a user to scroll forward and back in time. The NGFS Microphysics imagery at 1821 UTC, when the detection above first happened, is shown below. A simple probe shows that this detection is associated with a solar farm based both on a spectral analysis and a knowledge of where solar panels exist (if you look as the Google Basemap, available in the menu below, and zoom in, you’ll see the panels); given the sudden strong onset of a signal, perhaps a Fire Meteorologist would feel justified in ignoring the signal at these pixels (one clue is the vertical striping emanating northward/southward from the bright signature in Visible imagery, due to detector saturation from intense reflection of sunlight off the large Topaz Solar Farm). Note that information from more than one satellite band is needed to be certain that a solar farm is being detected.

Not long after, an actual fire did occur southeast of the Solar Panel detection (Note Highway 58 in all images!). The NGFS detection for that incident is shown below. It is detected as a Fire Pixel in this case.

The detected hot spot can be probed to detect the flammability of the pixels, as shown below.

One the fire has been named, that name (Bear Fire) is also included in the information on the NGFS website, and in the probe, as shown below.

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NOAA/NESDIS sponsored a Fire Weather Testbed in Boulder, CO the week of 10-14 June 2024 that included demonstrations of the NGFS detections, alerts dashboard, and satellite imagery on the NGFS website.

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