Tropical Storm Zeta in the Caribbean Sea
1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) and “Red” Visible (0.64 µm) images (above) showed Tropical Storm Zeta in the northwest Caribbean Sea on 25 October 2020. While it remained somewhat disorganized, Zeta slowly intensified from 35 knots to 45 knots during that time period. The coldest cloud-top infrared brightness temperature observed was -94.4ºC.GOES-16 Infrared images with an overlay of GLM Flash Extent Density (below) did reveal intermittent lightning activity with some of the more persistent areas of deep convection south of the analyzed storm center.
#Zeta has formed in the NW Caribbean – the 27th named storm of the 2020 Atlantic #hurricane season to date and earliest forming 27th Atlantic named storm on record. Prior record for earliest Atlantic 27th named storm formation was November 29, 2005. pic.twitter.com/9ugeQDkvx5
— Philip Klotzbach (@philklotzbach) October 25, 2020
===== 26 October Update =====
Zeta was upgraded to a Hurricane as of 1910 UTC as it approached the Yucatan Peninsula of Mexico on 26 October — 1-minute GOES-16 Infrared (with and without an overlay of GLM Flash Extent Density) and Visible images (above) showed the period of transition from Tropical Storm to Hurricane. The coldest cloud-top infrared brightness temperature was -95.4ºC near the storm center. Sea Surface Temperature and Ocean Heat Content images from the CIMSS Tropical Cyclones site (above) showed that Zeta was moving over very warm water, and deep-layer wind shear over the storm was very low (below) — all factors which were favorable for tropical cyclone intensification.