The role of anomalous soil moisture on the inland reintensification of Tropical Storm Erin (2007)

Abstract

Prior research on tropical storm systems that have made landfall and undergone a period of sustainability or reintensification has been linked to the synoptic environment at the time the storm restrengthened. Tropical Storm (TS) Erin is an interesting case study in that it did not take on hurricane-like structure nor reach hurricane intensity until it moved through west-central Oklahoma on August 19, 2007. This study seeks to examine the possible impact of anomalously wet soils across much of Oklahoma on the reintensification of TS Erin during the early morning hours of August 19, 2007. To determine the degree to which the antecedent soil state impacted TS Erin’s inland evolution and reintensification, analyses of the synoptic environment and the mesoscale environment/boundary layer environment are undertaken using operational and research datasets such as upper air soundings, surface soil moisture and temperature data, and multiple products from the Storm Prediction Center (SPC) mesoanalysis archive. This observational assessment is complemented with numerical experiments using the Weather Research and Forecast Model, Advanced Research Version 3.2 (WRF-ARW) to further study the role of soil moisture availability and surface fluxes that may have led to the boundary layer feedback and inland reintensification. Observational analysis and model results indicate that anomalously wet conditions over the central Oklahoma region may have helped develop a regional boundary layer feedback that appears to have contributed to the inland reintensification of TS Erin. Thus, the anomalously wet land surface had a positive role in TS Erin reintensifying over Oklahoma during the early morning hours of August 19, 2007.