The phrase "a small possibility that" is correct and usable in written English.
It can be used when discussing the likelihood of an event or situation occurring, indicating that there is a chance, albeit a minor one.
Example: "There is a small possibility that it might rain tomorrow, so you may want to bring an umbrella just in case."
Alternatives: "a slight chance that" or "a minor likelihood that".
Still, patients will need to be monitored for liver cancer, a small possibility that has been observed in mice.
"There is a small possibility that something still survived," Fatima's father said.
"Why would they put everything on the line for such a small possibility that they would get away with this?
There is a small possibility that Eros could one day strike Earth, scientists say, but that danger would not arise for another 1.5 million years.
There is a small possibility that Deutsche Telekom could revive talks in the future, but for now the negotiations with Qwest and U S West "are dead in the water," according to an executive close to the discussions.
There remains a small possibility that the gloom may be lifted in the show-jumping ring today but, even before the withdrawal of Fox-Pitt's horse, the mood in the British camp had been sombre.
Initial models showed that there was a very small possibility that it could impact Earth in February 2019, and this attracted a lot of media attention.
That imagined moment, though, has now become such a vanishingly small possibility that the final verdict on May's Brexit policy must now be of its conclusive and overwhelming failure.
Even though the EMS providers used semiautomated external defibrillators during the EMS resuscitation, there was a very small possibility that inappropriate shocks were given.
Prof Mark Sims of Leicester University, who commissioned the study, told BBC News that there is an extremely small possibility that Beagle 2 might still be working on the Martian surface.
This is the most parsimonious argument, but the authors do acknowledge the small possibility that a confounding difference in neurovascular coupling that has equal and opposite effects to a difference in neuronal activity between the groups could lead to the same overall BOLD signal.
