Simplify the following text for a Grade 8 native English-speaking person.
Original: However , in a post-storm analysis from the NHC , it was found that Grace attained peak winds of 65 mph ( 100 km\/h ) , slightly lower than operationally stated .
Simplified: However , the NHC found later that Grace 's highest winds were actually a little weaker , at 65 mph ( 100 km\/h ) .