1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed Laura during the the 12-hour period after it intensified from a Tropical Storm to a Hurricane in the southern Gulf of Mexico at 1215 UTC on 25 August 2020. Numerous convective overshooting tops were observed, some exhibiting cloud-top infrared brightness temperatures as cold as -87ºC.

A comparison of NOAA-20 MiRS Microwave (88 GHz), GOES-16 “Red” Visible (0.64 µm) and GOES-16 “Clean” Infrared Window (10.35 µm) images at 1851 UTC (below) revealed a curved convective band wrapping around the eye of Laura.

In a toggle between Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1943 UTC (below), the coldest cloud-top infrared brightness temperature was -91.9ºC in the Suomi NPP image (compared to -87.0ºC on the GOES-16 image). The northwestward parallax displacement associated with GOES-16 imagery over the southern Gulf of Mexico was also apparent.

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The Cooperative Institute for Meteorological Satellite Studies (CIMSS) acquires data directly from polar-orbiting satellites such as Suomi-NPP and NOAA-20 through Direct Broadcast antennae that are on the UW-Madison Campus. Community Satellite Processing Package (CSPP) software takes the Direct Broadcast signal and creates data files and, with Polar2Grid, imagery that are easily accessible at this ftp site where users can find directories for Suomi-NPP (ftp://ftp.ssec.wisc.edu/pub/eosdb/npp/) and for NOAA-20 (ftp://ftp.ssec.wisc.edu/pub/eosdb/j01/). ATMS and CrIS data (used in numerical modeling) are processed first and usually are finished processing in about an hour.

Direct Broadcast data is the fastest way to acquire data from Polar Orbiting satellites.

VIIRS True Color imagery (that is then fed to the CIMSS VIIRS Today Website), with a 375-m resolution (at nadir) has spectacular detail. The image above, from NOAA-20, (here is a link to the entire image, a link that will become stale after about 10 days) shows color variability over Lake Ontario at 1709 UTC.  The image below shows the Suomi-NPP scene of the same region 50 minutes later, at 1759 UTC (cut from this entire image.) One could compare the images and estimate lake surface currents.

The blog post immediately below this one notes the extensive smoke from Western Fires over the Midwest United States. The 1709 UTC image, below, shows the smoke pall along the east coast — but mostly north of the mouth of Chesapeake Bay.

Similarly, True-Color imagery at 1759 UTC on 25 August 2020 from Suomi-NPP shows thick smoke over much of the Midwest south of a frontal boundary over the western Great Lakes.

The Direct Broadcast Antenna in Madison can view acquire information from satellites that are over the northwest Caribbean, in northern Canada, and along the west coast of the United States, as shown by the dashed circle in this image (from this website). On 25 August, imagery of Hurricane Laura was available. The image below is the true-color image of Laura at 1759 UTC from Suomi NPP. Beneath that is the true-color image of Laura at 1849 UTC from NOAA-20. The two different satellites in similar orbits — 50 minutes apart — can be used to create high spatial resolution animations. This is easier to do when satellite data are re-projected onto a fixed grid, of course, as done for the VIIRS Today website. (NOAA-20 view or Laura today; Suomi-NPP view or Laura today, both from VIIRS Today.)

 

Both the VIIRS Today Website and the direct broadcast FTP directories include True Color, False Color, and Day Night Band imagery. Direct Broadcast imagery extends farther south and especially farther north than imagery at VIIRS Today. The Direct Broadcast ftp directory also contains images of individual ATMS channels, individual VIIRS channels (including the Day Night Band), MIRS products such as Rain Rate, and CLAVR-X cloud products (Rain Rate, Cloud Mask, Cloud Phase, etc.).

For the latest information on Hurricane Laura in the Gulf, refer to the National Hurricane Center.

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GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed the hazy signature of dense smoke aloft moving eastward across much of the Upper Midwest on 24 August 2020 — smoke that had been transported from large wildfires burning in California.

Images of 532 nm and 1064 nm lidar attenuated backscatter collected and processed by the University of Wisconsin Lidar Group at Madison from 00 UTC on 24 August to 00 UTC on 25 August (below) indicated that this smoke existed within altitudes between 2 km and 6 km.

CIMSS Natural Color RGB images with plots of Pilot Reports are shown below. While this “simple” RGB does not depict the haziness of the smoke as well as the True Color RGB images above — which are corrected for the effect of Raleigh scattering — s subtle smoke signature was still apparent. Not many of the available Pilot Reports (PIREPs) explicitly mentioned any effects of the smoke, but one 1955 UTC PIREP indicated a reduction to Marginal Visual Flight Rules (MVFR, visibility of 3-5 miles) at at altitude of 11,500 feet (3.5 km).

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Tropical Storm Laura’s path near/over the Greater Antilles has affected her strength, and the relative lack of organization means that night-time satellite identification of the center is a challenge. Consider the animation above. Northerly shear (analysis from this site) has shifted the coldest cloud tops to the south of the circulation center and with the 5-minute routine CONUS imagery, it is difficult to discern a surface circulation along the south coast of Cuba, where it was moving.  (A cluster of convection does appear there, although it is initially dwarfed in size by the convection to the south, south of 20 Latitude)

Visible imagery that becomes available at sunrise does show the center. The center gains prominence in the infrared as well as the convection to the south weakens. Note that the center can be discerned within the 1-minute shortwave infrared (3.9 µm) imagery from GOES-16 Mesoscale Sector 1: this link shows data from 0702 to 0803 UTC.  In the greyscale enhancement used in the linked-to animation, coldest cloud tops appear black and speckled because of a lack of precision at very cold temperatures in the 3.9 µm channel).

Sometimes, Day Night Band imagery from VIIRS can be useful in identifying tropical cyclone centers at night (see these 2016 examples with Matthew and Karl, for example). On the morning of 24 August, however, reflected moonlight was nil (Moonset over Cuba today was around 0500 UTC); in addition, the NOAA-20 overpass had Laura near the edge of the scan. Adaptive DNB imagery from Suomi NPP (just after 0700 UTC) and NOAA-20 (just before 0800 UTC), from the Direct Broadcast site at AOML in Miami, do show low clouds just south of Cuba, near the Jardines de la Reina, but it is a challenge to identify a surface circulation from this DNB imagery.

Interests in Cuba and along the Gulf Coast of the United States should monitor closely the progress of Laura. Refer to the National Hurricane Center website for the latest forecasts.

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