Irwin (2005)

A tropical depression formed about 135 nautical miles south of Manzanillo, Mexico near 1200 UTC on 25 August 2005. The system moved generally westward on the south side of a ridge, became Tropical Storm Irwin early on 26 August, and weakened back to a depression by early 28 August. Irwin lost its deep convection and became a non-convective remnant low late on 28 August about 490 n mi southwest of Cabo San Lucas, then moved west-southwestward and dissipated by 0000 UTC 3 September.

Irwin did not make any landfalls. It remained well offshore of Mexico throughout its life and no watches or warnings were issued.

The storm’s peak intensity was estimated at 45 knots (about 52 mph) with a minimum central pressure of 1000 mb, reached around 1200–1800 UTC on 26 August 2005. That intensity corresponds to a moderate tropical storm rather than a hurricane.

There were no reported storm surge measurements or notable rainfall totals associated with Irwin in the official report. Observations of winds and pressure were primarily from satellites and a single ship report; the report noted only one ship (call sign WCY845) that reported 37-kt winds but that observation was distant from the center and of uncertain reliability.

No damage or casualties were reported in association with Irwin. The cyclone was short-lived (about 72 hours as a tropical cyclone) and remained over open water, so impacts on populated areas were negligible.

Forecast track errors for Irwin were smaller than the 1995–2004 averages at 12–48 hours, and intensity errors were comparable to or slightly better than the 10-year averages. The storm’s brief duration and offshore track meant there were relatively few forecasts to evaluate.