Yes.
A forecast of storms or their probability requires an alternate unless it’s endorsed with tempo or inter.
Let’s also think of it practically. There’s a big cell at 8nm on the centreline of the most into wind runway. It’s affecting arrivals. The sequence slows. You’re held until they can slot you in.
The only time you’d disregard this is on an ETOPS flight. As long as the wx conditions are above landing minima, you’re good.