While it didn’t involve moving the Cerulean Storm, in it’s current location would eventually fill the Sunrise Sea and potentially the rest of the world. The Valley of Dust and Dire specifically always looked to be “lower” than the surrounding silt in the maps I’ve seen. A much larger area is now covered by the Cerulean Storm, but the silt is deep. I envision that in a few hundred/thousand years we’d see some open water, especially near the VoDaF but at the moment a good deal of the rain is being turned into steam, which makes the storm itself larger as more water is added into the clouds and more and more Tyr storms are being created. Take a look at the maps, look for depressions, and think about how much water it would really take to fill them. Without somebody specifically directing the storms, there’s not really a ton of water that the Tyr storms bring that will fill anything large enough to make a difference to a map. As the Cerulean storm itself grows however, we may very well be looking at a flooded world and a return to the Blue Age, it’ll just take longer then anyone but the Sorcerer-Kings and Rajaat have time to see.
The Cerulean Storm is roughly 100 miles across according to the maps. If we figure with the connection to the plane of water that it grows by even 1 mile a year, it would take about 350 years just to reach Giustenal and about 700 years to cover Tyr. If you figure 6 inches of rainfall an hour (heavy tropical storm) and an average depth for the Sea of Silt to be 12,000 feet (Average for Earth) it would take 2.7 years to fill any specific part of the old ocean. If we say the old Sunrise Sea is equivalent in depth to the most shallow ocean on earth (just over 4000 feet), has an area of roughly 540k miles, we’d still have 62 years to return the sea. Obviously this doesn’t take into account any water evaporation, absorption, or silt being compacted into a new ocean floor, north the growth of the storm. Figure a King’s Age to refill the Sunrise Sea assuming whatever originally caused the sea to turn to silt has burned out (I make that assumption and that the neck connecting the Sunrise Sea to the greater world’s silt oceans can be blocked off).
Per Beyond the Prism Pentad no Tyr storm lasts longer than an hour, most die in 20 minutes, you would typically see 2 inches for a normal storm and 6 inches for the slowest moving storms. The fastest hurricane moved at just under 70 miles per hour so from Cerulean Storm to Tyr you would get about 5-15 hours of storm as it crossed the Tyr region (based on 20 minutes to 1 hour comment). My Tyr Storms typically have a diameter of 80 miles (Hurricane Celia), never last longer then 24 hours (average hurricane) and roughly 8 a month get spun off but only one to the East capable of hitting the Tyr region. Additional Tyr Storms can be called by various parties.
If you plan to untether the Cerulean Storm from the VoDaF, I’d suggest making it much smaller so it doesn’t consume the entirely of the tablelands, a lot less destructive, and a lot less rainfall. Maybe it’s actually the size of a Tyr Storm but never burns out and just bounces around the tablelands as though confined to the area?
In my own campaign, I use a larger scale for the world so it takes a bit longer.
Tithian is inhabiting the body of a halfling and exerts a decent amount of control over the Tyr storms being spun off (at least some of them, when he concentrates) and he’s been hurling them and calling them down on his enemies as he builds his cult.
In the mean time, Dregoth has returned to life, moved to the surface with the Dray, and is busily recruiting humans to turn into Dray, has pushed the silt back from Giustenal’s walls and started calling more and more Tyr storms to the city, and is slowly trying to fill parts of the basin with water.
Draj is getting hit with more of the Tyr storms then even, causing some conflict but even with a growing cult of rain worshippers Atzetuk doesn’t have the power to turn away the wayward storms or really upset Dregoth. Atzetuk knows this, but with the warrior culture of Draj his inaction is starting to cost him some of his popularity and the constant repairs are starting to cut into the treasury. Even the proto-Tectuktitlay personality slowly trying to take him over knows he can’t really do anything more without stronger allies.
–edited for math