Looking at the weather data for the track (though they may have tested it closer to C&D headquarters), the 13th had the best air but there was also light rain off and on all day (DA of 318-1120 depending on time of day). There were some windows on the 11th and 12th that were 750-800' (light rain...
Car & Driver stated the launch control was a bit overzealous.
I'm a big fan of manuals (haven't owned an auto equipped performance car in 20+ years) but I'm seriously considering the Supra's.