| Tropical Storm (TS) Erin (2007) formed in the Gulf of Mexico in August of 2007. Its genesis and landfall were not unusual. What made Erin unique was how TS Erin's remnants re-strengthened over land in Oklahoma, after traveling 500km (310mi) for three days. During this re-strengthening Erin regained tropical characteristics. Erin did not gain its strength through extratropical transition (ET); it was warm-cored and symmetric at this time. The re-strengthening was made possible by the high soil moisture in Oklahoma and a low-level jet (LU). During the hours of Erin's re-development microvortices were present. These small scale rotations merged and strengthened the larger scale vortices in a process known as upscale growth. This continuous effect on the larger scale continued until it reached the scale of the cyclone, helping Erin re-strengthen to TS over land. |
