Iselle (2008)

An African easterly wave that crossed into the eastern Pacific produced a surface low near Central America on 8 August. Thunderstorm activity increased again late on 12 August, and the system became a tropical depression about 180 nautical miles south‑southwest of Manzanillo, Mexico at 1200 UTC 13 August. It strengthened to Tropical Storm Iselle six hours later and moved generally west‑northwest to northwest before weakening to a depression early on 16 August and becoming a remnant low about 24 hours later roughly 1,270 nautical miles west‑southwest of the southern tip of Baja California. The remnant low drifted west and then southwest, redeveloped a little convection on 22 August, and dissipated on 23 August.

Iselle did not make any landfalls on the Mexican coast or on inhabited islands. The storm passed just south of Socorro Island while at tropical storm strength, but no direct landfall on that island or other land was recorded in the official track.

The storm’s maximum sustained winds peaked at 45 knots (about 52 mph) on the morning of 14 August, with a minimum central pressure of 999 mb at that time. Iselle remained a weak tropical storm throughout its lifetime and never reached hurricane strength.

There were no reports of storm surge or notable rainfall impacts tied to Iselle in populated areas in the NHC report. In-situ observations of tropical-storm‑force winds from ships or land stations were not received, and no specific surge heights or rainfall totals for cities or counties were recorded in the official record.

No deaths or damage were reported in association with Iselle. The cyclone produced little impact on land and caused no reported casualties.

Forecasts initially struggled to anticipate the timing of formation: several days before genesis models suggested high odds of development but the system did not form then, and explicit mention of depression formation appeared only about 12 hours before it occurred. Track forecast errors were larger than recent averages through 48 hours, while intensity forecasts were notably better than the long-term averages.