JMA Himawari-9 Clean Infrared Window (10.4 µm) images, from 0002 UTC to 2102 UTC on 07 December [click to play animated GIF | MP4]

Target Sector (2.5-minute interval) JMA Himawari-9 AHI Clean Infrared Window (10.4 µm) images (above) showed the gradual development of a ragged eye with Cyclone Jasper as the storm moved southward across the Coral Sea on 07 December 2023. Intermittent convective bursts within the eyewall contained a few overshooting tops that exhibited infrared brightness temperatures around -90ºC (yellow pixels embedded within dark purple areas).

DMSP-17 SSMIS Microwave (85 GHz) image at 0816 UTC on 07 December [click to enlarge]

The partially-fragmented structure of the eyewall was evident in a DMSP-17 SSMIS Microwave image at 0816 UTC (source) (above) and a RCM-1 Synthetic Aperture Radar wind speed image at 0807 UTC (source) (below).

RCM-1 Synthetic Aperture Radar wind speed image at 0807 UTC on 07 December [click to enlarge]

Himawari-9 Infrared Window (11.2 µm) images from the CIMSS Tropical Cyclones site (below) showed that Jasper was moving through an environment of low deep-layer wind shear — which, in addition to its motion across warm water (SST | OHC) favored continued intensification.

JMA Himawari-9 Infrared Window (11.2 µm) images, with contours and streamlines of deep-layer wind shear at 1500 UTC on 07 December [click to enlarge]

Jasper was upgraded to Category 3 intensity at 1800 UTC (JTWC discussion) — and a DMSP-17 SSMIS Microwave image at 1927 UTC (below) displayed a more organized eyewall structure.

DMSP-17 SSMIS Microwave (85 GHz) image at 1927 UTC on 07 December [click to enlarge]

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