The pilot was conducting the return leg of a charter flight, when weather conditions deteriorated about 130 kilometres from the destination. Thunderstorms were evident on either side of track and converging ahead of the aircraft. The pilot elected to return to the DEPARTURE aerodrome, however approaching this strip the weather again deteriorated to the point where flight in visual conditions was not possible. After searching for over an hour to find a clear route to another aerodrome, the pilot elected to land in what appeared to be a suitable paddock. During the landing roll, the nosewheel sank into the soft surface and the nosegear was dislodged. The pilot had only limited experience in operating in the Northern Territory during the wet season, and had probably not received sufficient training and supervision from the aircraft operator.