Hurricane Michael reaches Category 3 intensity

October 9th, 2018 |

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GOES-16 “Clean” Infrared Window (10.3 µm) image, with Metop-A ASCAT surface scatterometer winds [click to enlarge]

Metop-A ASCAT scatterometer data (above) showed surface wind speeds as high as 64 knots near the storm center while Michael was at Category 2 intensity just northwest of Cuba at 0307 UTC on 09 October 2018.

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0752 UTC (below; courtesy of William Straka, CIMSS) revealed transverse banding north of the storm center on the Infrared image, and mesospheric airglow waves propagating westward away from Michael on the Day/Night Band image.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

5-minute GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images from 0517-1332 UTC (below) showed a series of relatively brief convective bursts around the storm center, but in general Michael exhibited a somewhat disorganized appearance during that time period.

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GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

After sunrise, 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (below) revealed the gradual formation of a more well-defined eye during the day, with episodic clusters of convective “hot towers” developing in the southeastern and eastern portions of the eyewall — which then rotated around to the north and northwest of the eye. By 18 UTC Michael had intensified to a Category 3 storm.

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GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

1-minute GOES-16 “Clean” Infrared Window images (below) indicated that infrared brightness temperatures associated with these hot towers were often as cold as -80º to -89ºC (violet to darker purple enhancement).

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GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

Michael had been encountering unfavorable deep-layer wind shear and had also been moving over a pocket of water with low Ocean Heat Content northwest of Cuba (below). However, once the hurricane began to move over waters having higher OHC in addition to warm Sea Surface Temperature, it gradually began to intensify from a Category 2 to a Category 3.

Ocean Heat Content and Sea Surface Temperature, with a plot of the track of Michael [click to enlarge]

Ocean Heat Content and Sea Surface Temperature, with the track of Michael [click to enlarge]

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