How Does the Land Surface Condition Affect Precipitation and Intensity of Hurricane Harvey (2017) after Landfall?

The 2017 North Atlantic hurricane season has brought with it devastating socioeconomic impacts. Six tropical cyclone (TC) landfall events have occurred so far along the United States Gulf coast, with two of those landfalls associated with category-4 hurricanes. In addition to the damaging wind and storm surge that accompanied these landfalling hurricanes, extremely heavy rainfall occurred and led to freshwater flooding. The most extreme rainfall and flooding occurred in conjunction with Hurricane Harvey, which made landfall northeast of Corpus Christi, Texas, just after 0000 UTC 26 August 2017 as a category-4 storm. Following landfall, Harvey was sustained at tropical storm intensity for the next 84 hours as it remained nearly stationary over southeast Texas and produced over 1200 mm of rainfall in regions from Houston to Beaumont, Texas. The historic inland freshwater flooding in the southeast Texas coastal zone contributed to over 30 fatalities and an estimated $190 billion in damage.

The ability of Harvey to maintain tropical storm strength over southeast Texas for over 3 days after landfall while producing historical rainfall and flooding prompts questions about the role of the underlying land surface condition in Harvey's structural evolution, maintenance, and focus of precipitation. The aim of this presentation is to combine NASA satellite and reanalysis products with a suite of high-resolution Weather Research and Forecasting (WRF) model simulations to address three science questions: 1) How did the soil moisture and precipitation evolve as Harvey made landfall and remained nearly stationary for 84 hours? 2) How did the heterogeneously evolving soil moisture/land surface conditions influence the physical processes that drive heavy precipitation? 3) What influence did the evolving underlying soil moisture conditions have on Harvey's intensity after landfall? Preliminary results show that soil moisture dramatically increased within ~100 km of the Texas coastline in the 84 hours subsequent to Harvey's landfall. The suite of WRF simulations will specifically test the sensitivity of Harvey's intensity and rainfall production to the underlying soil moisture condition utilizing moisture and vorticity budget diagnostics.