LightningCast in cold air

December 11th, 2021 |
RealEarth presentation of GOES-16 Clean Window infrared along with contours of LightningCast Probability (10 (blue), 25 (cyan), 50 (green) and 75 (purple) %). GLM Flash Extent Density is also shown. Data are every 5 minutes from 0700 – 1000 UTC on 11 December 2021 (Click to enlarge)

LightningCast probabilities are part of the ProbSevere portfolio, and they are available in RealEarth (link). This machine-learning product relates Band 13 and Band 15 observations to the probability of lightning occurrence (in daytime, Band 2 and Band 5 are also used). When your blogger was awakened by thunder (at 0826 UTC), as cold rain fell on the roof, he naturally thought: “I wonder what LightningCast is doing?” The animation above shows probabilities increasing as lightning developed over southern Wisconsin. Initial lead time for lightning from the probabilities is not big — but probabilities do expand and encompass the region that is experiencing lightning. The time of the lightning did match the closest approach of the surface low, as shown in this 0900 UTC surface analysis.

That lightning was produced in near-freezing surface temperatures reflects the vigor of this extratropical system that spawned a deadly tornado outbreak over the mid-Mississippi River Valley and lower Ohio River Valley (SPC Storm Reports).

GLM observations of a long-track tornado

December 11th, 2021 |
GOES-16 GLM Total Optical Energy, 2101 UTC on 10 December through 0600 UTC on 11 December 2021 (Click to enlarge)

Gridded GLM observations of Total Optical Energy, above, capture the tornado-producing long-lived storm that hit Mayfield KY (and others) on 10 December. This storm had its genesis in eastern Arkansas, and it moved northeastward through the bootheel of Missouri, then into western Kentucky. It was mostly isolated from a line of convection to its west until it approached Louisville at around 0600 UTC, when the cells began to join together.

GLM observations of Average Flash Area for the same time period are shown below.

GOES-16 GLM Average Flash Area, 2101 UTC on 10 December through 0600 UTC on 11 December 2

Viewing Fall lightning with RealEarth

October 21st, 2021 |

Cooler temperatures across the Midwest are often heralded by thunderstorms. Yesterday evening and last night, a system brought rain and lightning to parts of Iowa, Minnesota, Wisconsin, Illinois, and Michigan, moving over Ohio by Thursday morning. RealEarth, a web-based visualization platform developed at UW-Madison, can display data from GOES-16 to monitor such events. RealEarth’s data archives usually go back at least 24-hours which provides temporal context to weather events.

RealEarth is a free data discovery and visualization platform developed at SSEC/CIMSS at the University of Wisconsin-Madison. It is available at

A 24-hour animation every hour from RealEarth (time in UTC) showing GOES-16 ABI Band 13 with the purple areas representing lightning. More specifically, the purple areas depict Flash Extent Density from the Geostationary Lightning Mapper (GLM) also aboard GOES-16.

Meteorologists Monitor Meteor

September 29th, 2021 |

According to the JPL site, there was a bright meteor (or bolide) on September 29, 2021 over the Gulf of Alaska. (The JPL and a similar NASA site are posted under the GLM tab on this link of links.) This event was seen by both the ABI and GLM on NOAA‘s GOES-17, as well as the AHI on Japan’s Himawari-8. What may be unique about his event is that the imagers monitored the meteor soon after it’s explosion, and not just the resulting plume (as was done in this case over Russia in 2013). This is based on the length of the event, during which the various spectral bands displayed a signature and other information.

Peak Brightness DatePeak Brightness Time (UT)Latitude (deg.)Longitude (deg.)Altitude (km)Total Radiated Energy (J)Calculated Total Impact Energy (kt)
2021-09-29 10:50:5953.9N148.0W2813.7e100.4

Entry from table via the JPL site.


The GLM and ABI observed this event, but given it’s faster readout, the GLM offers much more information than the ABI. The apparent location of the meteor as seen by the ABI is different than the reported location, in part due to parallax. More on the concept of parallax is available here.

Animation of GOES-17 ABI band 12 (9.6 mirometer) mesoscale sector #2 on September 29, 2021.

Hotter brightness temperatures can be seen in the GOES-17 ABI band 12 at 10:50:59 UTC.

Animation of all 16 bands of the GOES-17 imager on September 29, 2021. Note band 12.

Indicative of a short duration event, coupled with how the ABI scans, the meteor signature was only clearly seen at one time in nearly every ABI spectral band (although possibly the ABI band 11 as well). Due to the layout of the focal plane array on the ABI, not all spectral bands observe the Earth at the precisely same time. [Figure a modification from the GOES-R Series Data Book.] A similar loop as above, but as an animated gif, is available here. In addition,. while a bit hard to see, the longwave split window infrared difference also showed a subtle signature of the meteor.

Spectral difference images (over time) can also be useful in the monitoring of meteors. An ABI 10.3 – 12.3 micrometer band difference is shown below. An shortwave minus longwave difference loop.

An animation of the GOES-17 difference image between ABI 10.3 – 12.3 micrometer bands. The brightness temperature range is -5 to +5K.

The GLM on GOES-17 also observed this event. A similar loop as below, but as an animated gif, is available.

ABI band 12 and the GLM Flash Event Group density on September 29, 2021. Credit: CIRA/RAMMB Slider.

The rapid movement of the meteor to the south is clearly evident. As well as the GLM group map and the key (blue is early times and red is later times).

GOES-17 GLM meteor location over time and space on September 29, 2021 with larger circles (color coded to intensity). Credit: Todd Beltracchi.

As well as the changes over time, most likely monitoring the meteor break-ups.

GOES-17 GLM meteor over time on September 29, 2021. Credit: Todd Beltracchi.

More on the GLM’s light curves from NASA AMES.


Both the ABI and Japan’s AHI scan space around the edge of the Earth. However, with the ABI data the process of making calibrated, navigated, and remapped radiance only pixels located on the Earth are included in the Level 1b radiance files. Hence, the ABI may scan meteors in space, but the data are not available to most users.

All 16 spectral bands from Himawari-8 AHI at the same nominal time (10:50 UTC) on September 29, 2021.

A similar loop as above, but as an animated gif, is available here (and an 8-panel AHI image at this same time is available here). This example helps to illustrate that each AHI detector doesn’t sense radiation from the same exact location at the same time.


NOAA GOES17 data were accessed via the University of Wisconsin-Madison SSEC Satellite Data Services. McIDAS-X and Geo2Grid was used to generate imagery. Thanks also to Todd Beltracchi and Scott Bachmeier, and to CIRA/RAMMB Slider images/movies.