One forecaster says that the chance of a storm tomorrow is 1.3.

Step 1. Neither. A probability lies from $0$ to $1$. A chance of $1.3$ would be more than certain, and $-0.2$ less than impossible.

Step 2. Zero. It cannot happen: rolling a 7 on an ordinary die.

Step 3. One. It is certain: rolling a number less than 7 on an ordinary die.