At the moment my main ranked deck is Monsters weather, it was tooth and nail to get to rank 16 for the first time last month, but it is still workable with the tweaks I've made.
In my experience, if you are using drowners, jotunn is enough. If you throw in a gold weather or woodland spirit/ifrit for a commander's horn target, Aard might be the better option, but jotunn has helped me win a lot of battles even without frost on the board (and I don't have aard). To me, the choice is between drought and jotunn or Aard and white frost, but jotunn is more flexible than Aard and takes less forethought. I also like monster nest: I run one rider to play iris into, and can always spawn another one with Eredin if I have to, so I have the option of spawning a buffed drowner or, most often, a 16+ strength ghoul in the final round as the nail in the coffin. With the ghoul buff, this has become a very solid finisher. I also run one archgriffin to slightly disrupt discard decks and give my monster nest a juicy target in round 3.
Only use your weather when enemy is going to have to go for a long round. It might seem obvious, but my passing game has to be tight or I will lose. I've had a lot of luck lately winning the first round and bullying them to win the second. If your mulligans and draws are weak, you can drypass to get a second chance and take them in round 3, but you really need round one.
Don't underestimate lacerate and dbomb as alternatives to merrigolds. I've been stuck with a dead merrigolds in the last round far more than I've expected. It doesn't remove targets for buffing from swarm decks or hit golds, and people love to row stack against weather.
I only run 2 hounds and 3 frosts. That way, I can just have eredin throw a frost or navigator to draw the second hound if I want a low tempo weather play to bait out a clear.