By Scott Bachmeier •
From its inception as a highly-sheared Tropical Storm on 04 October, Nicole moved in an erratic path with small intensity fluctuations for 8 days (above); then a period of intensification began on 12 October, with the storm reaching Category 4 intensity southwest of Bermuda at 03 UTC on 13 October. With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 90% of full) Nicole exhibited a well-defined eye on Suomi NPP VIIRS Day/Night Band (0.7 µm) imagery at 0615 UTC, with cold cloud-top temperatures surrounding the eye on the corresponding VIIRS Infrared Window (11.45 µm) image (below). As Nicole approached Bermuda, increasing deep-layer wind shear began to impact the storm and weaken it to a Category 3 — and DMSP-17 Microwave (85 GHz) data showed that the eye had become open to the south (below). The passage of Nicole over Bermuda is shown on GOES-13 Visible (0.63 µm) and Infrared Window (10.7 µm) images spanning the period 1037-1555 UTC (below). As the eye of Nicole passed over Bermuda around 13 UTC, the staff at the Bermuda Weather Service were able to successfully launch a rawinsonde balloon, which reported data as high as the 202 hPa pressure level or 12.2 km altitude — much higher than their previous launch attempts at 06 and 12 UTC (below). The Total Precipitable Water (TPW) value derived from that 15 UTC sounding was 72.5 mm or 2.85 inches, which was in general agreement with that displayed by the MIMIC TPW product. Note that the eye of Nicole did not appear to be directly over Bermuda on the 1300 UTC GOES-13 images — this is due to a combination of parallax and the fact that the eye had a significant southwest-to-northeast tilt with height. A sequence of Infrared images from POES and Metop AVHRR (12.0 µm) and Terra MODIS (11.0 µm) during the period 1016 to 1513 UTC is shown below.Categories: AVHRR, GOES-13, Metop, MODIS, POES, Suomi NPP, Terra, Tropical cyclones, VIIRS