Atlantic Tropical Depression Five strengthened to become Tropical Storm Erin over the western Gulf of Mexico, shortly before making landfall as a minimal tropical storm near Lamar, Texas, on the morning of August 16, 2007. During the overnight hours of 18-19 August 2007, nearly three full days after landfall, the remnant circulation of Erin strengthened to exceed tropical storm criteria over western Oklahoma. Radar imagery clearly shows the re-development of an eye and eyewall structure and banding characteristic of a tropical cyclone over water. Upper-air observations indicate that the intensification was tropical in nature, despite occurring approximately 500 miles inland from Erin's landfall point.

Observations from the Oklahoma Mesonet reveal sustained winds near the circulation's center exceeded 40 mph for a duration exceeding three hours, the strongest sustained winds reported during any time in Erin's life-cycle. Sea-level pressure observations from the Mesonet also indicate lower central pressures than during any period of Erin's life cycle. Together, these indicators suggest that Erin was a stronger storm when nearly 500 miles inland than when it was over water.

This presentation will detail the redevelopment and intensification of Erin over Oklahoma. It will include comprehensive surface observations with 1-minute and 5-minute resolution, radar overview, and discussion of the synoptic, mesoscale and topographic influences on the intensification process.