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Hurricane Douglas moves just north of Hawai’i

By Scott Bachmeier •

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed  Category 1 Hurricane Douglas as it moved just north of Hawai’i during the day on 26 July 2020 (the boundary of the Mesoscale Sector was abruptly shifted westward at 1658 UTC). The coldest cloud-top infrared brightness temperatures were around -80ºC.

GOES-17 “Clean” Infrared Window (10.35 µm) images, with analysis of deep layer wind shear at 20 UTC [click to enlarge]

GOES-17 “Clean” Infrared Window (10.35 µm) images, with analysis of deep-layer wind shear at 20 UTC [click to enlarge]

The apparent storm center as seen in satellite imagery was shifted north of the actual surface center location, due to the presence of southerly/southwesterly deep-layer wind shear as shown by a 20 UTC analysis from the CIMSS Tropical Cyclones site (above). This offset was also evident in a comparison of a DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC with the analyzed surface position of Douglas at 1800 UTC (below).

DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC, with the analyzed surface position of Douglas at 1800 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC, with the analyzed surface position of Douglas at 1800 UTC [click to enlarge]

===== 27 July Update =====

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 Visible and Infrared images (above) showed that the low-level circulation became exposed from the deep convection of Douglas a few hours after sunrise on 27 July, as it moved southwestward near the island of Nihoe. An analysis of deep-layer wind shear at 22 UTC (below) indicated the presence of 25-30 knots of southwesterly shear over that area — an unfavorable environment for tropical cyclone intensification/maintenance, in spite of the fact that the storm was moving over favorably-warm water.

GOES-17 “Red” Visible (0.64 µm) images, with analysis of deep layer wind shear at 22 UTC [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) images, with analysis of deep-layer wind shear at 22 UTC [click to enlarge]

Categories: DMSP, GOES-17, Microwave, Satellite winds, Tropical cyclones