GOES-17 Imagery in this post is preliminary and non-operational.

GOES-16, operational as GOES-East at 75.2º W Longitude, and GOES-17, in a check-out mode at 89.5º W Longitude, viewed convection in and around Houston TX (apparent in the clear skies at the start of the animation) on 8 August 2018 (Click here for animated gif). Stereoscopic views of this convection (achieved by crossing your eyes until 3 images appears, and focusing on the image in the middle) reveal the three-dimensional nature of the convection, in particular the effects of an outflow boundary propagating northward towards Houston.

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* GOES-17 images shown here are preliminary and non-operational *

“Red” Visible (0.64 µm) images from GOES-17 and GOES-16 (above) showed the circulation and convective banding associated with Subtropical Storm Debby in the Atlantic Ocean on 07 August 2018.

Deep-layer wind shear analysis from the CIMSS Tropical Cyclones site (below) indicated that Debby was in an environment of low shear.

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1-minute Mesoscale Domain Sector “Red” Visible (0.64 µm) images from the AOS site (above) showed the circulation of Hurricane John as it was intensifying from a Category 1 to a Category 2 storm off the west coast of Mexico on 07 August 2018. Several tropical overshooting tops could be seen in the animation.

GOES-16 Upper-level Water Vapor (6.2 µm), Mid-level Water Vapor (6.9 µm), Low-level Water Vapor (7.3 µm) and “Clean” Infrared Window (10.3 µm) images (below) revealed an interesting gravity wave that was propagating northward away from the center of John. This wave appeared to perturb the cloud tops — perhaps via vertical mixing — leading to a slight warming of the colder cloud-top infrared brightness temperatures as the wave passed. The appearance and behavior of this wave was very similar to another observed in Nebraska, Colorado and Kansas on 22 July.

Another item of interest was the circulation of weakening Tropical Storm Ileana being absorbed by the larger circulation of intensifying Hurricane John — this process was illustrated by 3-hourly 850 hPa relative vorticity analyses derived from GOES-15 (GOES-West) satellite winds (below). Similar results were seen at the 700 hPa, 500 hPa and 200 hPa pressure levels.

===== 08 August Update =====

GOES-15 (GOES-West), GOES-14, GOES-17 and GOES-16 (GOES-East) Visible images (above) showed 4 views of Hurricane John after it had diminished to a Category 1 storm on 08 August.

Note that the GOES-15 and GOES-14 Visible images do not appear as bright as those from GOES-17 and GOES-16 — prior to the GOES-R Series of satellites, the performance of visible detectors degraded over time, leading to imagery that appeared more dim as the Imager instrument aged. Visible detectors on the new ABI instrument benefit from on-orbit calibration to remedy this type of degradation.

* GOES-17 images shown here preliminary and non-operational *

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* GOES-17 images shown here are preliminary and non-operational *

A toggle between NOAA-20 and Suomi NPP VIIRS Infrared Window (11.45 µm) images (above; courtesy of William Straka, CIMSS) showed the well-defined eye of Hurricane Hector after it had reached Category 4 intensity on 06 August 2018 (advisories: EPAC | CPAC).

GOES-17 “Red” Visible (0.64 µm) images (below) revealed cloud-top gravity waves within the eyewall region of the storm, along with thin filaments of transverse banding in the northern semicircle farther from the eye.

GOES-15 (GOES-West) Visible (0.63 µm) and Infrared Window (10.7 µm) images (below) showed that eyewall cloud-top infrared brightness temperatures were in the -70 to -80ºC range (black to white enhancement).

A magnified view of GOES-15 Visible images (below) revealed mesovortices within the eye of Hector.

Metop ASCAT surface scatterometer winds (below) surrounding the eye were near 70 knots around 1930 UTC.

The MIMIC-TC morphed microwave product (below) showed that Hector underwent an eyewall replacement cycle early in the day on 05 August, and then maintained a well-defined eye as it subsequently strengthened to a high-end Category 4 intensity on 06 August (ADT | SATCON).

===== 07 August Update =====

A nighttime NOAA-20 VIIRS Day/Night Band (0.7 µm) image (above) revealed the presence of mesospheric airglow waves (reference) propagating northwestward away from Category 4 Hurricane Hector on 07 August. Note that these high-altitude waves were not apparent on the corresponding Infrared Window (11.45 µm) image.

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