Cosme — 2025

Cosme formed from a broad area of low pressure in the eastern North Pacific about 500 nautical miles southwest of the coast of southwestern Mexico. The system became a tropical depression at 0600 UTC 8 June 2025 and strengthened into Tropical Storm Cosme about six hours later. It moved north-northwestward from formation through dissipation, remaining well offshore and dissipating by 0000 UTC 12 June 2025. Cosme did not make landfall and no coastal watches or warnings were issued. The storm remained over open water for its entire life and did not produce any reported direct impacts on land. Cosme’s peak intensity was estimated at 60 knots (about 69 mph) with a minimum central pressure of 991 millibars. That peak lasted from 1800 UTC 9 June through 1200 UTC 10 June. Satellite and remote-sensing data supported those estimates, with some instruments showing slightly different peak values (e.g., SAR indicated about 63 kt in one quadrant and ASCAT showed 45–50 kt). There were no reports of storm surge or notable rainfall impacts associated with Cosme—no coastal tide or flood observations attributable to the storm were reported in the NHC record, and no rainfall totals at populated locations were cited. No damage or casualties were reported in association with Cosme; the storm produced no confirmed direct or indirect fatalities. The NHC issued an abbreviated report reflecting the lack of coastal impacts and the absence of reported damage. Noteworthy items include that Cosme’s genesis was first highlighted in NHC outlooks 54–60 hours before formation and that forecast track and intensity errors were generally smaller than the recent 5-year means at many forecast times. Remote-sensing differences in peak wind estimates (ASCAT vs. SAR) were noted and SAR-derived winds are still being evaluated for use in operational intensity estimates.