The image above shows the Level 2 GOES-R product, Aerosol Optical Depth (AOD), a product created in clear skies, overlain with the GOES-16 Visible imagery from the same time. AOD measures the extinction of light via scattering and absorption by small particles in the atmosphere, and it can be used as a proxy for particles smaller than 2.5 µm in diameter (PM25). The red regions show the highest values. The plot below shows surface observations of ceilings (plotted to the left of the circles) and visibility (plotted below the circles) at the same time as the AOD image above. Is there a relationship?

Look at the string of lower visibilities stretching along the North Carolina/South Carolina border, extending westward to Tennessee and then northward into Illinois. This is the region where AOD exceeds about 0.4 — cyan in the enhancement used above. In this instance, AOD can be used to highlight regions where surface visibilities are most restricted by aerosols. (Some of these aerosols are likely from smoke. However, this product does not tell you what kind of aerosol is there, only that it is causing extinction).

The toggle below steps through the observations, AOD, and Visible imagery at 1401 UTC. Kudos to Frank Alsheimer, the Science and Operations Office (SOO) in Columbia SC, for alerting us to this case.

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True-color imagery, below, (saved in this case from the CSPP Geosphere site, using this link) also shows the extent of the aerosol-rich air.

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The relationship between AOD values and surface visibility persisted on 23 July 2021, below.

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5-minute GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature RGB images (above) revealed that the Dixie Fire in northern California produced a pair of pyrocumulonimbus (pyroCb) clouds — denoted by cloud-top 10.35 µm infrared brightness temperatures of -40ºC or colder (shades of blue pixels) — late in the day on 19 July 2021. The first pyroCb formed at 2241 UTC, with the second at 2331 UTC, Maximum surface 3.9 µm brightness temperature sensed with this fire was 138.7ºC — which is the saturation temperature for the ABI Band 7 detectors.

GOES-17 Day Land Cloud Fire RGB images (below) include plots of GLM Flash Extent Density and contours of ProbSevere LightnngCast probability — and show that LightningCast probability exceeded 50% as early as 2241 UTC (the time of the initial pyroCb formation), with the first GLM lightning being detected 40 minutes later at 2321 UTC. LightCast probability first exceeded 75% at 2341 UTC — with GLM Flash Extent Density increasing in coverage and intensity 30 minutes later after 0011 UTC (associated with the second pyroCb anvil as it drifted north-northeastward).

This case demonstrates that LightningCast can clearly help improve wildland fire incident awareness and assessment (and safety).

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An F5 tornado struck the village of Oakfield, Wisconsin late in the day on 18 July 1996 (NWS Milwaukee story). An animation of GOES-8 (GOES-East) Visible images (below) showed the development of supercell thunderstorms as they moved east-southeastward across the area. Oakfield is located just southwest of Fond du Lac (KFLD), and is denoted by the yellow ‘+’ symbol on the images. Overshooting tops were evident on these thunderstorms.

The corresponding GOES-8 Infrared Window images (below) revealed cloud-top infrared brightness temperatures as cold as -63.6ºC (darker shades of red) at 2345 UTC, which was approximately 30 minutes prior to the tornado moving through Oakfield (the GOES-8 imager instrument was actually scanning the Oakfield area at 2348 UTC).

On a larger-scale view of GOES-8 Water Vapor images (below), a sharp gradient of warm-to-cool brightness temperature — orange/yellow to blue enhancement, portraying the gradient of dry air to moist air — highlighted the presence of a middle-tropospheric jet streak that was moving southeastward across the state.

Examples of Derived Product Images from the GOES-8 Sounder can be seen here.

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Lightning safety is important for aircraft, mariners, and many outdoor activities. CIMSS is working to evaluate a model that nowcasts lightning. This model was trained using GOES-16 ABI visible, near-infrared, and long-wave infrared channels, as well as GOES-16 Geostationary Lightning Mapper (GLM) observations. It predicts the probability of lightning (IC or CG, as observed by GLM) in the next 60 minutes at any given point. The model routinely provides lead-time to lightning initiation of 20 minutes or more. We’re hopeful that one day such a model will help forecasters provide guidance for aviators, mariners, and decision support services (DSS) for things like sporting events, festivals, and theme parks. Near-real-time model output can be viewed using SSEC’s RealEarth.

Below are a few examples, with the forecast lightning probability contoured over the daytime cloud phase RGB and GOES-16 GLM flash-extent density.

So this summer, whether you’re going to the South Carolina beach,

or sailing in the Gulf of Maine,

or hiking in the Rocky Mountains,

or catching the first MLB game in Iowa,

be on the lookout for lightning!

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