An intelligent downhole impact jar device is described that is able to sense well bore angle or deviation and alter the effective jar impact load based upon the sensed information. The impact jar device includes a jarring portion for creating jarring impacts within a wellbore toolstring. The jarring portion is adjustable so that jarring forces of various levels can be produced. The jarring portion is adjusted in response to sensed wellbore conditions, such as the angle of deviation of the surrounding wellbore.