I haven't had a chance to say Hi yet wordjunkie - so Hi!!

And welcome.

As for "likely", you'll likely find me a lone voice here, but my university professor was dead set against all "ly" words. The argument was that they take a statement into the passive tense - when scientific articles should be more active. To my mind, "only" and "likely" sort of fall between the cracks though. Even so, I'd use "There is potential for rain" or "There's a chance of rain".

I've moderated my stance to accept them in conversational english however.

Anyway, the statement that it is probably unlikely that rain will actually happen is generally untrue!!

stales