An EF-3 tornado moved through the southwest Wisconsin town of Boscobel, in Grant County, late in the afternoon of 7 August 2021 (Preliminary Storm Summary from WFO ARX). The tornado was on the ground from 4:29 to 4:56 PM CDT, or 2129 – 2156 UTC. How did the ABI imagery and GLM data change over this time? The Satellite Information Familiarization Tool (SIFT) can be used to investigate this. Gridded GLM data that can be imported into SIFT (a two-week rolling archive is available) is available at this website. ABI Radiance data can be acquired from NOAA CLASS or from the Amazon Cloud.

The GOES-16 ABI Clean Window animation from 2100 to 2159 UTC, bracketing the times that the tornado, linked to the image above, shows very strong upper-level difluence (consider how the cirrus shield spreads south in the hour of the animation!); one might infer cyclonic motion in the fields as well.

SIFT allows for the identification of regions that can then be investigated. The toggle below shows a polygon that has been defined. Subsequent plots will focus on this region surrounding the storm tops associated with the tornadic storm.

How do the cloud-top brightness temperatures evolve in that region? One way to describe that is a simple bar-graph showing the distribution of temperatures, shown below. There are three distinct cold temperature events: around 2130 UTC, around 2138 UTC, around 2148 UTC. (Recall the tornado is on the ground fron 2129-2156) The time-scale of the changes is such that only 1-minute imagery will be able to capture it accurately.

How do the lightning observations evolve in the storm? SIFT will display many different GLM parameters: Average and Minimum Flash Areas, Total Energy, Group (and Flash) Extent and Centroid Densities, Group and Flash Areas. Some are displayed below, again within the confines of the polygon defined above. The first plot compares Average Flash Area (along a constant x axis) and Total Optical Energy (along a varying y axis). The distribution in the plot seems to change during the time when the tornado is on the ground.

SIFT also allows direct comparisons between ABI and GLM data, as shown below: Flash Extent Density is compared to Band 13 (10.3 µm) brightness temperatures at discrete times within the tornado’s lifecycle.

For more information on SIFT, including download instructions for linux, MacOS and Windows, refer to the SIFT website.

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GOES-16 CONUS sector imagery, above, captured from CSPP Geosphere (link), over Tropical Depression Fred just north of eastern Cuba in the Atlantic Ocean, shows a ragged circulation with very little convection in the center (click here to download the mp4 above). Fred has been disrupted by its passage over the terrain of Hispaniola. Fred is embedded within southwesterly shear as shown below; that shear and the lack of convection near the center limits the speed with which Fred will be able to intensify.

Will dry air limit Fred’s intensification? MIMIC (Morphed Integrated Microwave Imagery at CIMSS) Total Precipitable Water (TPW) imagery at 1700 UTC on 12 August 2021, below, shows some pockets of dry air over the central Caribbean, and to the north of Fred and just west of Fred (and a large area of dry air to the east). (Note also Pacific Hurricane Linda to the south of Mexico at the western edge of the domain!) Overall however, the environment seems moist.

Gridded NUCAPS estimates of low-level moisture in the form of 900-700 mb mean Relative Humidity, below, and of 850-500 mb mean Relative Humidity, at bottom, are more indicative of dry air in the lower troposphere surrounding the storm. Gridded fields of NUCAPS relative humidity are available online here.

For more information on Fred, refer to the National Hurricane Center website (here) or the SSEC/CIMSS Tropical Weather website (here).

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The VIIRS Today website (link) contains daily imagery from the Day Night Bands on both Suomi NPP and on NOAA-20. For example, here are three images from Suomi-NPP on 12 August over the Pacific Northwest and northern California: 2-km resolution, 1-km resolution, and 250-km resolution. The animation below shows Day Night Band imagery over northern California, showing the development of the Dixie Fire (14 July) and its expansion and motion over the subsequent weeks. The animation was derived from 1-km resolution imagery.

Smoke from the fire is occasionally obvious in the imagery (for example on 2 August), depending on the amount of lunar illumination. Clouds also cover the fire at times, but the light emanated from the fire shines through. A fire to the east that is in progress when the Dixie fire starts is contained during the first week of the animation. Other fires are apparent as well, but the Dixie Fire is the longest-lasting one in the animation. The Dixie Fire has occasionally burned hot enough to product pyrocumulonimbus clouds, as shown here.

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Shortwave Infrared (3.9 µm) images from GOES-17, GOES-15, GOES-14 and GOES-16 [click to play animation | MP4]

The GOES-14 satellite was brought out of storage on 11 August 2021, for its annual checkout activities (NOAA bulletin). Shortwave Infrared (3.9 µm) images (above) provided a 4-GOES view of the thermal anomalies (or hot pixels, darker black enhancement) exhibited by the Richard Spring Fire in southeastern Montana. On that day the fire had burned over 149,000 acres, and was only 15% contained. The 4 panels of images are displayed in the native projection of each satellite.

GOES-14 Imager spectral band images at 1755 UTC on 11 July 2021 (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to enlarge]

The GOES-14 Imager has the same 5 spectral bands (above) as GOES-15 (below).

GOES-15 Imager spectral band images at 1800 UTC on 11 July 2021 (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to enlarge]

A sequence of Infrared images from EWS-G1 (formerly GOES-13), GOES-17, GOES-15, GOES-14 and GOES-16 — between 1345 UTC and 1500 UTC on 13 August — is shown below. Full-resolution data from all 5 of the GOES were received by satellite antennas operated by SSEC Satellite Data Services.

Sequence of Infrared images from EWS-G1 (formerly GOES-13), GOES-17, GOES-15, GOES-14 and GOES-16 (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to enlarge | MP4]

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