The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.

Tweets on Tuesday 7 March 2017 highlighted the fast-moving fires over the High Plains (that began burning on 6 March), and they also highlighted different bands available from the GOES-16 ABI. For example, this tweet references the loop above, showing an animation of 3.9 µm temperatures; that shortwave infrared channel is used because it is more sensitive to hot temperatures than longer wavelength infrared channels. The Norman WFO also tweeted out imagery, shown below, that included the 0.86 µm ‘Veggie’ band and the 0.47 µm visible band. Why use those two channels?

The 0.47 µm imagery is observing a part of the visible electromagnetic spectrum where scattering is largest, so smoke plumes are more apparent at that wavelength than at 0.64 µm. For a very obvious event such as this one, this might not be as important, but for a modest fire event over Florida, shown next, it can be. The 0.86 µm imagery is useful because it very distinctly shows fire burn scars; that is, the contrast at 0.86 µm between vegetated soil and adjacent burned regions is greater than occurs at other visible wavelengths. That is shown in the toggle below that steps through 0.47 µm, 0.64 µm, 0.86 µm, 1.61 µm and 3.9 µm imagery for one time on 7 March. The smoke plume is most distinct at the shortest wavelength 0.47 µm; it is very difficult to discern at 0.86 µm and especially at 1.61 µm because these near-infrared channels sense radiation at longer wavelengths that is unaffected by scattering of light by the small smoke particles. Note, however, that the small lakes do jump out at both wavelengths because of the very different reflectance properties of land and water at both 0.86 µm and 1.61 µm.

Finally, compare the 0.64 µm and 0.86 µm with special focus on the burn scars (here is a toggle between the two). Although the spatial resolution is greatest in the 0.64 µm visible imagery (0.5 km at the sub-satellite point, vs. 1 km at the sub-satellite point for the 0.86 µm imagery), the burn scars nevertheless are more distinct at 0.86 µm, in part because vegetated ground is more reflective at 0.86 µm than at 0.64 µm (See the figure in ‘Tim’s Topics’ on page 2 of the 0.86 µm fact sheet).

=========================================================================A less extensive fire event occurred on 10 March 2017 in Florida. Focus on the largest hot spot (black pixels) in the 3.9 µm imagery in the center of the top third of the image below; this point is in southeastern Polk County. For this event, the smoke plume is more easily visualized in the 0.47 µm imagery than in the 0.64 µm or the 0.86 µm imagery. A burn scar does not appear in this case.

The GOES-R Website includes Fact Sheets for Band 1 (0.47 µm), Band 2 (0.64 µm), Band 3 (0.86 µm), Band 5 (1.61 µm) and Band 7 (3.9 µm).

AWIPS Note: The default enhancement (“IR_COLOR_CLOUDS_WINTER”) for 3.9 µm results in imagery that shows too little gradation over Florida during the daytime; for fire detection, either modify the colormap (this changed the temperature range from the default [-109 to 55] to -70 to 75, and is shown above) or switch to the”IR_COLOR_CLOUDS_SUMMER” enhancement.

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** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

GOES-16 Visible (0.64 µm) images (above; also available as an MP4 animation) showed multiple undular bores over western Texas on 10 March 2017. The wave packets were perturbing the low-altitude fog and stratus clouds across the region during the morning hours, in advance of a cold front that was approaching from the north. One bore was moving toward the south, while another (apparently deeper) bore was moving toward the southwest.

A plot of 12 UTC rawinsonde data from Midland (below) revealed the presence of a strong low-level temperature inversion from the surface to the 850 hPa  pressure level — this inversion was acting to duct the gravity waves as they propagated southward and southwestward.

Even though the undular bores were relatively shallow features, a subtle signature of the southwestward-moving bore was seen in Middle-Level Water Vapor (6.9 µm) and Lower-Tropospheric (7.3 µm) images (be1ow).

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** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

(Hat tip to T.J. Turnage, NWS Grand Rapids, for alerting us to this case): A variety of mesoscale wave structures were seen in NOAA GOES-16 Lower-Tropospheric Water Vapor (7.3 µm) and Middle-Tropospheric Water Vapor 6.9 µm images (above; also available as an MP4 animation) within a dry slot along the southern periphery of a trough associated with a large and intense mid-latitude cyclone centered over Hudson Bay, Canada on 08 March 2017. Beneath this dry slot, wind gusts exceeded 60 mph across southern portions of Minnesota, Wisconsin and Lower Michigan as momentum aloft was mixed downward to the surface.

Using the GOES-13 (GOES-East) Sounder water vapor bands as a proxy for the three ABI water vapor bands, weighting functions calculated using 12 UTC rawinsonde data from Chanhassen, Minnesota (below) showed a dramatic downward shift in the weighting function curves (compared to a US Standard Atmosphere) — this meant that the 3 water vapor bands were sensing radiation from layers much closer to the surface on 08 March (where the strong winds could interact with terrain and cause standing waves to form). It is interesting to note that the outline of the southern part of Lake Michigan could be seen on GOES-16 Lower-Tropospheric Water Vapor (7.3 µm) imagery (animated GIF | MP4 animation) — the signal of the thermal contrast between the lake water (MODIS SST values in the upper 30s to low 40s F) and the adjacent land surfaces (MODIS LST values in the middle 50s to low 60s F) was “bleeding up” through what little water vapor was present aloft.

A comparison of GOES-16 Visible (0.64 µm) and Middle/Lower-Level Water Vapor images (below; also available as an MP4 animation) showed that these water vapor wave structures were forming in cloud-free air — this is a signature of the potential for low-altitude turbulence.

In fact, there were widespread pilot reports of moderate turbulence within the dry slot (below), with a few isolated reports of severe to even extreme turbulence in eastern Wisconsin and southern Lower Michigan.

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Widespread large grass fires began to burn across parts of northwestern Oklahoma, southwestern Kansas, and the Texas Panhandle on 06 March 2017. The fires grew very quickly during the late morning and early afternoon hours, due to strong southwesterly winds (with gusts as high as 67 mph in Oklahoma) behind a dryline (surface analyses); a cold front then moved southward across the region during the late afternoon and evening hours, bringing strong northerly/northwesterly winds.

*  GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

In the 2-panel comparison shown above (also available as a 204 Mbyte animated GIF), Shortwave Infrared (3.9 µm) images — 1-minute interval (Mesoscale Sector) 2-km resolution GOES-16 vs. 5-7 minute interval (Rapid Scan Operations) 4-km resolution GOES-13 — fire “hot spots” (dark black to yellow to red pixels) from the large Starbuck Fire can be seen making a very fast northeastward run from the eastern Oklahoma Panhandle into southwestern Kansas, behind the dryline; later, after the passage of the cold front, the leading edge of that fire and another large Kansas fire turned southward and moved back into Oklahoma. Another large fire in the Texas Panhandle (the Perryton Fire) moved rapidly eastward and crossed the border into Oklahoma (moving a distance of about 45 miles), before also turning abruptly southward in the wake of the aforementioned cold frontal passage. A total of 7 deaths resulted from these fires (CNN).

===== 07 March Update =====

On the following day, the large size of the grass fire burn scars could be seen in comparisons of true-color and false-color Red/Green/Blue (RGB) images from Terra MODIS (1732 UTC), Suomi NPP VIIRS (1857 UTC) and Aqua MODIS (1912 UTC) images viewed using RealEarth (below). The burn scars appeared as dark areas in the true-color images, and shades of tan to darker brown in the false-color images.

The creation of true-color and false-color images such as these will be possible using the ABI spectral bands available on GOES-16 and the GOES-R series of satellites. A separate blog post highlighting other multi-spectral GOES-16 views of these fire burn scars on 07 March  is available here.

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