I honestly have moved the rule out of RM into Node Red. So this is going from memory.
I believe I used Rule Machine to create a text variable, and into that variable I stored the value from the attribute "weather" using "custom attribute" in Rule Machine.
Then as @Chris_C said, I had if-thens that said, if the variable contained "rain" or "thunderstorm" or "drizzle" or "snow" then announce "It is precipitating, consider closing the windows."
My original question wasn't really to figure out how to do it, I needed to find a list of all the possible states of "weather" so that I could make the rules.
I'm not sure if that answered your question.... if not, let me know.