Cosme (2019)

A tropical wave that left Africa on 23 June crossed into the eastern North Pacific and gradually organized. A broad low formed along the wave axis on 4–5 July, and a well-defined center developed by 1200 UTC 6 July about 650 nautical miles west-southwest of Manzanillo, Mexico. Cosme existed as a tropical cyclone from 6–7 July 2019 before losing its deep convection and becoming a post-tropical remnant low by 0000 UTC 8 July. The remnants continued northwestward, then westward, and dissipated by 11 July.

Cosme did not make any landfalls. The circulation remained well offshore of Mexico and the Baja California Peninsula for the storm’s entire tropical-storm phase, and no coastal watches or warnings were issued.

The storm’s maximum sustained winds were 45 knots (about 52 mph) with a minimum central pressure of 1001 mb, corresponding to a weak tropical storm at peak intensity. Cosme reached this peak essentially at genesis (around 1200–1800 UTC on 6 July) and then gradually weakened as dry air, marginal ocean temperatures, and wind shear limited further development.

There were no reports of storm surge or measured coastal inundation associated with Cosme, and no significant rainfall totals were reported in the official record for impacted communities. An automated Mexican Navy station on Isla Clarion reported sustained winds of 31 kt (36 mph gust) around 2100 UTC 6 July when the center was roughly 150 n mi to the south-southwest.

No deaths, injuries, or damage were reported in association with Cosme. Forecasts detected the precursor system well in advance; genesis was highlighted in the Tropical Weather Outlook up to several days before formation. Because Cosme was short-lived, only a few verifying forecasts exist, but official intensity errors were typical for recent years while track forecasts showed a modest south–west bias for this system.