Elsa briefly regains hurricane intensity before making landfall along the Florida coast

July 6th, 2021 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

Late in the day on 06 July 2021, Tropical Storm Elsa regained hurricane intensity as of 0000 UTC, just off the west coast of Florida. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the tropical cyclone during the 1500 UTC to 0000 UTC time period. In the morning, cloud-top infrared brightness temperatures of -80ºC or colder were seen (violet pixels), but during most of the day they were in the -70 to -79ºC range. While Elsa had been moving over water with Sea Surface Temperature values around 28ºC, the Ocean Heat Content of those waters was relatively low.

For a few hours the low-level circulation of Elsa remained exposed from its deep convection to the northeast — and GOES-16 Visible images with an overlay of deep-layer shear at 1800 UTC, from the CIMSS Tropical Cyclones site (below), showed that this was due to westerly shear values around 25-30 knots over the area.

GOES-16 “Red” Visible (0.64 µm) images, with an overlay of deep-layer wind shear at 1800 UTC [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) images, with an overlay of deep-layer wind shear at 1800 UTC [click to enlarge]

The center of Elsa moved just to the east of Buoy 42023 — a plot of wind speed/gust and pressure is shown below.

Plot of wind speed/gusts and pressure at Buoy 42023

Plot of wind speed/gusts and pressure at Buoy 42023

A DMSP-15 Microwave (85 GHz) Microwave image at 2155 UTC (below) indicated that Elsa had nearly completed the formation  of a closed eyewall at that time.

DMSP-15 Microwave (85 GHz) Microwave image at 2155 UTC [click to enlarge]

DMSP-15 Microwave (85 GHz) Microwave image at 2155 UTC [click to enlarge]

GOES-16 Infrared  / Water Vapor Difference images (below) revealed pockets of stronger overshooting tops near the center of deep convection during the hours leading up to Elsa reaching hurricane intensity.

GOES-16 Infrared / Water Vapor Difference images [click to enlarge]

GOES-16 Infrared  / Water Vapor Difference images [click to enlarge]

===== 07 July Update =====

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

After once again weakening to Tropical Storm intensity at 0600 UTC, Elsa eventually made landfall along the coast of Florida around 1500 UTC on 07 July, as seen in 1-minute GOES-16 Visible and Infrared images (above) — inland impacts included an EF0 tornado, wind gusts to 71 mph and rainfall exceeding 11 inches (NWS Public Information Statements).

At 1223 UTC, a DMSP-17 SSMIS Microwave image (below) indicated that a closed eyewall was not present with Elsa at that time.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

Cyclone Tauktae in the Arabian Sea

May 16th, 2021 |

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared (10.7 µm) images (above) showed Cyclone Tauktae in the Arabian Sea (just off the west coast of India) as it intensified from a Category 1 to a Category 3 storm on 16 May 2021.

A DMSP-18 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed a fully enclosed eye at 1142 UTC, shortly before Tauktae reached Category 3 intensity at 12 UTC.

DMSP-18 SSMIS Microwave (85 GHz) image at 1142 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 1142 UTC [click to enlarge]

===== 17 May Update =====

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared (10.7 µm) images [click to play animation | MP4]

EWS-G1 Infrared images (above) showed Cyclone Tauktae making landfall along the coast of India around 1745 UTC on 17 May, with a Category 3 intensity (ADT | SATCON).

Rapid intensification of Super Typhoon Surigae

April 16th, 2021 |

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation]

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation]

2.5-minute interval rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) showed Typhoon Surigae undergoing rapid intensification (ADT | SATCON) to become a Category 4 storm as of 18 UTC on 16 April 2021.

A DMSP-16 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) displayed a well-defined eye, with distinct spiral bands feeding into the eyewall.

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

After sunrise, Himawari-8 “Red” Visible (0.64 µm) images (below) showed the relatively compact eye, with hints of low-level mesovortices within the eye.

JMA Himawari-8 "Red" Visible (0.64 µm) images [click to play animation]

JMA Himawari-8 “Red” Visible (0.64 µm) images [click to play animation]

===== 17 April Update =====

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

The prolonged period of rapid intensification continued overnight, and as of 12 UTC on 17 April Surigae had become a Category 5 Super Typhoon — 2.5-minute interval rapid scan Himawari-8 Infrared images (above) showed the well-defined eye as the storm tracked northwestward across the Philippine Sea (just east of the Philippines). A faster animation (GIF | MP4) helped to highlight the trochoidal motion (wobble) of the eye — a behavior often seen with intense tropical cyclones. The 21 UTC advisory from JTWC listed sustained winds of 165 knots (and objective intensity estimates from ADT and SATCON were around 170 knots), making Surigae the only tropical cyclone on record to reach that intensity during the month of April.



An animation of Himawari-8 Infrared images with an overlay of deep-layer wind shear (below) indicated that Surigae was moving through a region of low to moderate wind shear; the storm was also moving across very warm water (SST + OHC).

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Around the time that Surigae was reaching its peak intensity, a Suomi NPP VIIRS Day/Night Band (0.7 µm) image several hours before sunrise (below) revealed concentric mesospheric airglow waves (reference) propagating away from the energetic Category 5 tropical cyclone.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

In closer view of time-matched Himawari-8 Infrared and Suomi NPP Day/Night Band images (below), a cluster of bright DNB pixels highlighted the presence of lightning activity along the inner edge of the northern eyewall.

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Cyclone Habana in the South Indian Ocean

March 10th, 2021 |

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared Window (10.7 µm) images (above) displayed the well-defined eye and eyewall structure of Cyclone Habana in the South Indian Ocean on 10 March 2021. This was the second period of Category 4 intensity (ADT | SATCON) during the life cycle of Habana.

Meteosat-8 Infrared images with contours of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) showed that Habana was moving through an environment of relatively low shear.

Meteosat-8 Infrared images, with contours of deep-layer wind shear [click to enlarge]

Meteosat-8 Infrared images, with contours of deep-layer wind shear [click to enlarge]

Meteosat-8 Infrared images with an overlay of 1505 UTC Metop ASCAT winds (below) depicted a fairly uniform distribution of winds within the eyewall region, as Habana developed an annular structure.

Meteosat-8 Infrared images, with a plot of Metop ASCAT winds [click to enlarge]

Meteosat-8 Infrared images, with a plot of Metop ASCAT winds [click to enlarge]

SSMIS Microwave (85 GHz) images from DMSP-16 at 1139 UTC and DMSP-18 at 2327 UTC are shown below.

DMSP-16 SSMIS Microwave (85 GHz) image at 1139 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1139 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 2327 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 2327 UTC [click to enlarge]