Background
A flight service station (FSS) had forecast thunderstorm activity for the 24-hour period following the pilot's departure. Despite this forecast, the pilot decided to depart in order to personally evaluate the weather situation.
Flight Details
Conditions encountered during the flight were consistent with the forecast. The pilot elected to return to the airport from which he had departed. However, due to the movement of the storm system behind the flight, a return to the departure airport was not possible.
Precautionary Landing
The pilot then decided to perform a precautionary landing in an unimproved field. The field had appeared smooth when the pilot overflew it earlier. The terrain, however, proved to be rougher than anticipated.
Outcome
During the landing rollout on the rough terrain, the aircraft nosed down. The incident concluded with the aircraft in a nose-down attitude.