Anyone who lives somewhere hot where it can go lengthy periods without rain, even if it is just a seasonal thing, should understand why this rainfall isn't going to solve the draught, even if the sheer amount of water that fell theoretically could have in a basic model that doesn't account for what happens during a lengthy period without rain.

Even just a few months here without rain and the ground is so hard, it becomes more like hardened clay than soil or dirt, and the rain doesn't seep into it quickly, meaning any winds, slopes, etc. make it just roll/flow away before it saturates the soil.

It takes times for the soil to become pliable and accept rain, and I don't know the actual science about it but I sure know that when it gets dry in the summer here, the first heavy rains don't feel like they've done much for how much rain there was, and it seems like all they've done is fill up pools.

By the time it has rained a few times and the ground gets more receptive to absorbing water, the rains definitely have a notably different impact.

That is after 1-4months of fairly dry weather, and I live somewhere with exceptionally high humidity. California has had many, many years of draughts far more extreme and very little humidity, so it is going to take far more than just a few torrential rains before they get anywhere close to being out of a draught. You can't expect the reversal of many years of something extreme to occur within just a short period of the opposite, at least not in most situations.

Yep. Water likes to stick to water. If the ground has some moisture already the water is more than happy to go into the ground with all of its other water molecule buddies. If the ground is completely dry it takes more time so it will either pool up or just keep flowing.