May 8th, 2021 | Scott Bachmeier
1-minute Mesoscale Domain Sector GOES-17 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the convective banding associated with Tropical Invest 90E in the East Pacific Ocean on 08 May 2021. Invest 90E was centered along a northward bulge in the ITCZ/Monsoon Trough (below).
Invest 90E was located over water characterized by modest Ocean Heat Content and very warm Sea Surface Temperature values (below), a favorable factor for further intensification.
===== 09 May Update =====
1-minute GOES-17 Infrared and Visible images on 09 May (above) showed the period where Invest 90E intensified to a Tropical Depression (at 0900 UTC) and then to Tropical Storm Andres at 1500 UTC — the earliest calendar year tropical storm on record in the East Atlantic basin. The convective overshooting tops occasionally exhibited infrared brightness temperatures of -90ºC (yellow pixels embedded within dark purple regions).
A GOES-17 Infrared / Water Vapor Difference product (reference) from the CIMSS Tropical Cyclones site (below) highlighted areas of deep convection where overshooting tops were likely penetrating the tropopause (yellow to red enhancement).
GOES-17 Infrared images, with an overlay of deep-layer wind shear (below) indicated that Andres was approaching an environment of moderate to high shear, which would limit intensification.