  Unexpected dynamic phenomena have surprised solar system observers in the
past and have led to important discoveries about solar system workings.
Observations at the initial stages of these events provide crucial information
on the physical processes at work. We advocate for long-term/permanent programs
on ground-based and space-based telescopes of all sizes - including Extremely
Large Telescopes (ELTs) - to conduct observations of high-priority dynamic
phenomena, based on a predefined set of triggering conditions. These programs
will ensure that the best initial dataset of the triggering event are taken;
separate additional observing programs will be required to study the temporal
evolution of these phenomena. While not a comprehensive list, the following are
notional examples of phenomena that are rare, that cannot be anticipated, and
that provide high-impact advances to our understandings of planetary processes.
Examples include: new cryovolcanic eruptions or plumes on ocean worlds; impacts
on Jupiter, Saturn, Uranus, or Neptune; extreme eruptions on Io; convective
superstorms on Saturn, Uranus, or Neptune; collisions within the asteroid belt
or other small-body populations; discovery of an interstellar object passing
through our solar system (e.g. 'Oumuamua); and responses of planetary
atmospheres to major solar flares or coronal mass ejections.
