Persistent region of cool sea-surface temperatures in the tropical Eastern Pacific
GOES-16 sea-surface temperatures on 1 April 2021 show a region of much cooler temperatures — values around 74ºF , green in the color enhancement used) — surrounded by warmer sea-surface temperatures (values in the mid-80sºF, yellows and oranges in the color enhancement) to the southwest of Nicaragua. Why does this cool region exist? Typically, cool ocean surface temperatures can originate via upwelling (Note in the image above cool temperatures along the Equator where persistent upwelling exists). Is the part of the ocean that is cool above affected by upwelling? Cool temperatures are apparent to the northwest as a result of oceanic upwelling from a Tehuano wind through the Chivela mountain pass (similar to this event from 2018). There is a similar gap in the mountains between Costa Rica and Nicaragua (link). Perhaps a persistent wind through that gap during the past months initiated this cool patch. As shown below, the cool patch has been quite persistent — it was apparent in mid-January.