Nearly the entire continent of Antarctica was illuminated by 24 hours of daylight, as seen on JMA Himawari-8 Visible (0.64 µm) images (below; also available as a 60 Mbyte animated GIF). Full-disk images are routinely available at 10-minute intervals from Himawari-8 (and can be available as frequently as every 5 minutes from the GOES-R series).With the continuous daylight, Antarctic surface air temperatures from AMRC Automated Weather Stations (below; source) were seen to warm above 40ºF along the coast, and above -30ºF in the interior.
The corresponding EUMETSAT Meteosat-10 Visible (0.64 um) images (below; also available as a 17 Mbyte animated GIF) provided a more detailed look at the structure of the storm during the daylight hours of those 4 days.Daily snapshots of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using RealEarth are shown below. The hazy signature of blowing dust/sand from northern Africa could be seen within the broad southeast quadrant of the storm circulation. There was ample moisture available to fuel convection around the storm, as seen in the MIMIC Total Precipitable Water product (below). The surface wind circulation of the medicane was well-sampled on a variety of Metop-A and Metop-B overpasses, using ASCAT plots (below) from this site. Suomi NPP ATMS images (below; courtesy of Derrick Herndon, CIMSS) revealed the areal coverage of the small “warm core” on Channel 8 (54.94 GHz) and Channel 7 (53.596 GHz); a north-to-south oriented vertical cross section showed the depth of the thermal anomaly associated with the medicane. For additional information, see this blog post from the Capital Weather Gang.
EUMETSAT Meteosat-10 Visible (0.75 µm) and Infrared Window (10.8 µm) images (below; also available as an MP4 animation) revealed the development of thunderstorms over southern Norway during the 0900-1300 UTC period. Cloud-to-ground lightning from one of these storms is believed to have killed 323 reindeer near the southeastern corner of the Hardangervidda National Park (which is located in the center of the visible and infrared satellite images).The coldest cloud-top infrared brightness temperatures of the thunderstorms on the 1100 UTC image was -51º C, which corresponded to an altitude of around 10.5 km on the 1200 UTC Ørland rawinsonde report (below) — looking at the individual sounding profiles, Ørland to the north of Hardangervidda was still in the moist convective environment near the center of the storm system, while Stavanger to the south began to show the drier air aloft in the wake of the northeastward-moving storm. A composite of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image swaths as viewed using RealEarth (below) showed the widespread thunderstorms across southern Norway on the earlier (eastern) 1103 UTC overpass, while the later (western) 1243 UTC overpass showed the effects of the mid-level drier air that was beginning to overspread the region as the center of the parent storm system moved northeast.
EUMETSAT Meteosat-7 Infrared Window (11.5 µm) images (below) showed the formation of a well-defined eye after about 03 UTC.A comparison of Meteosat-7 Infrared (11.5 µm) and DMSP-18 SSMI Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (below) showed the eye structure around 15 UTC.
===== 18 April Update =====During the 17-18 April period Cyclone Fantala reached Category 5 intensity (ADT plot), with maximum sustained winds of 150 knots (making it the strongest tropical cyclone on record in the South Indian Ocean); Fantala also became the longest-lived hurricane-strength tropical cyclone on record for that ocean basin. Meteosat-7 Infrared Window (11.5 µm) images (above) showed the storm reaching peak intensity as it moved just north of the island of Madagascar.
A comparison of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below) offered a detailed nighttime view of the eye of Fantala at 2249 UTC on 17 April. Side lighting from the Moon (in the Waxing Gibbous phase, at 81% of full) helped to cast a distinct shadow within the eye, and also provided a good demonstration of the “visible image at night” capability of the Day/Night Band.