GOES-16 Visible Imagery, above, shows Tropical Storm Henri east of Florida and to the north of the Bahamas. Cirrus outflow is well-developed to the east and south, but the storm is sheared; the surface circulation is near the northwestern edge of the ongoing deep convection. Persistent northerly shear, as shown below in a figure taken from the CIMSS Tropical Website, shows Henri moving from a region of relatively high shear towards a region of relatively smaller shear.

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GCOM-W1 overflew Henri at 0616 UTC on 20 August. Microwave imagery, below, (retrieved from the AOML Direct Broadcast site) confirm the sheared nature of the storm at that time. Both frequencies show that deep convection is displaced to the south of the storm center.

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Suomi NPP overflew the storm at around 0600 UTC, and the toggle below shows the Day Night band visible (0.7 µm) imagery and the I05 infrared (11.5 µm) imagery; included in the toggle are Advanced Clear Sky Processor for Oceans (ACSPO) SST values in clear regions. Atlantic Ocean waters have surface temperatures in the 84-85º F range. Cloud top temperatures are as cold as -86º F for this overpass. (Suomi NPP VIIRS data were processed at the CIMSS Direct Broadcast site and injected into AWIPS).

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The animation of the Airmass RGB, below, shows a prominent feature over the mid-Atlantic states of the United States that will have a big role in Henri’s future path: a mid-tropospheric potential vorticity maximum highlighted as red/orange in the Airmass RGB. The toggle at bottom compares the 1211 UTC Airmass RGB with contours of pressure (mb) on the 1.5 PVU surface.

For the latest on Henri, refer to the National Hurricane Center Website. Residents of southern New England and Long Island and New Jersey in particular should pay close attention to this storm.

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Grace (then a tropical storm) is shown in AWIPS above, in between Jamaica and the Caymans, in Day Night Band Visible imagery, along with VIIRS I05 Infrared imagery, from 0626 UTC, using data from the Direct Broadcast site at CIMSS. The coldest cloud tops with the most vigorous convection, shown as white/blue in the color enhancement, are near -89º C. The visible imagery has sufficient lunar illumination (more than on Monday 16 August with Fred!) that the tallest cloud tops are casting shadows. The few cloud-free pixels that are present allow ACSPO sea-surface temperatures to be computed: 30º C or 86º F.

NOAA-20 and Suomi-NPP give infrequent views of the storm. GOES-16 is the better choice for storm monitoring. The animation below shows the Convection RGB over the storm. The Convection RGB is useful because it can highlight regions of vigorous convection (in orange/yellow). The RGB highlights convective banding near the center of the storm and also on the periphery of the storm.

GOES-16 Water Vapor imagery, below, shows the environment in which the storm is forming. The upper-level water vapor imagery, 6.19 , below, begins near the time of the Suomi-NPP overpass (imagery shown above)and continues until about 1600 UTC. It shows a rapid organization to the storm — certainly the satellite presentation changes over the 10 hours of this animation! There does seem to be dry air to the north of Grace, just north of Cuba. How that affects the storm in the future is to be determined.

Total Precipitable Water fields, below, for the 24 hours endings at 1500 UTC on 18 August, also show some dry air near the storm. However, Grace has access to plenty of moisture in the near term. Tropical storm Henri, Pacific Hurricane Linda, and the remains of Fred are also apparent in the imagery.

Grace is in an environment of low shear, and is over very warm water, as shown in this image, a 1500 UTC 200-850 mb shear and SST analysis taken from the CIMSS Tropical Website.

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JAXA‘s GCOM-W1 satellite, carrying the AMSR-2 instrument, overflew Grace near 1900 UTC on 18 August, and imagery (taken from the AOML Direct Broadcast website) from 36.5 and 89.0 GHz is shown above (note that 89.0 GHz imagery is used in MIMIC-TC imagery available at the CIMSS Tropical Website). Both microwave representations show a distinct eye in the storm, most especially at lower levels.

True-Color imagery from CSPP Geosphere, below, shows convection persistently developing around the storm center as it moves through the northwest Caribbean towards the Yucatán Peninsula.

1-minute Mesoscale Domain Sector #GOES16/#GOESeast Infrared images of #Grace, from the time it reached hurricane intensity (15 UTC on 18 August) to it making landfall along Mexico's Yucatan Peninsula (0945 UTC on 19 August): https://t.co/Qa6m8flCs5 pic.twitter.com/VfgnjnEuv0

— Scott Bachmeier (@CIMSS_Satellite) August 20, 2021

More information on Grace is available at the National Hurricane Center.

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Detection of smoke is a challenge in regions with clouds. The bright reflectance from clouds can make the subtler (and usually not so bright) smoke features difficult to view. This blog post briefly shows how visible imagery can be manipulated to facilitate smoke detection. The animation above shows visible imagery (GOES-16 Band 2 at 0.64  µm) at 2-km resolution. The sixteen half-km pixel visible reflectances within the larger pixel have been averaged to create the 2-km resolution image, and a square-root enhancement (from 0-100%) has been applied.

August 4 was a day with a smoke pall over much of the upper midwest, as suggested below by HRRR Smoke Model output below. How distinct is that pall in the imagery above, especially in regions of cumulus and cirrus clouds, such as over northeastern Minnesota? Can the visible imagery above be manipulated so that smoke features are enhanced?

The animation below shows 2-km resolution data again (with a square-root enhancement applied), but instead of the mean reflectance value from the 16 1/2-km pixels used, the minimum reflectance of those 16 pixels is shown. The smoke in the air is more noticeable (and the clouds are less noticeable).

You can also display the maximum pixel value of the 16 1/2-km pixels within the 2-km pixel footprint. That’s shown below (also using a square-root enhancement). This brings out the clouds at the expense of smoke detection.

A PowerPoint presentation that contains the imagery above is here. Thanks to Andy Heidinger, NOAA, for these images.

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The Caldor Fire (east of Sacramento, California) exhibited unprecedented growth on 17 August 2021 — increasing from 3600 acres burned in the morning to 30,000 acres that evening, with 0% containment — and Shortwave Infrared (3.9 µm) images from 1-minute GOES-17, 15 to 30-minute GOES-15, 15 to 30-minute GOES-14 and 5-minute GOES-16 (above) displayed a rapid expansion of the fire’s thermal anomaly (large cluster of hot pixels, darker black enhancement; the white pixels seen in GOES-15 images were due to a “wrap-around” effect with that satellite’s saturated 3.9 µm detectors). Each of the 4 image panels are displayed in the native projection of that particular satellite.

GOES-17 True Color RGB images created using Geo2Grid  (below) showed the large amounts of smoke (and frequent pyrocumulus clouds) produced by the Caldor Fire.  

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