Foresight manifests itself as an intense form of 'deja vu' in which present events align with 'future' events and trigger a mental response in which sights, sounds, and/or emotions resonate with those in an alternate reality.
What this means is that foresight cannot be actively used. It is a passive sense, and while can be 'listened for' it can not be 'activated.' Sensory data transfer is erratic, however, with time and training the unpredictableness of the ability can be refined within a mental 'filter,' given one additional 'possibilities' to consider, but never to rely on.
Foresight is mostly seen with Alterra, but occasional instances have been documented in both Lanteans and Humans where they have developed lesser forms of the Alterran Tennatis nodule, but significantly advanced enough to acquire a limited version of the ability.
After being genetically altered by the Goa'uld Nirti using an abandoned Alterran device, Jonas grew a primitive tennatis nodule within his brain. Unlike in most cases, telepathic and telekinetic skills were not manifested, but the rarer foresight ability was, briefly. The crude tennatis nodule was unstable, and had to be surgically removed from his brain before killing him.