Most of us rely on the weather forecast to choose our outfit or make outdoor plans for the weekend. But conditions underwater can also be useful to know in advance, especially if you’re an oyster farmer, a fisher or even a recreational diver.

A new University of Washington computer model can predict conditions in Puget Sound and off the coast of Washington three days into the future. LiveOcean, completed this past summer, uses marine currents, river discharges and weather above the water to create the forecasts.

“It’s like a weather forecast of the ocean in our region,” said lead developer Parker MacCready, a UW professor of oceanography. The project is the culmination of about 15 years of work. “It started off small, modeling parts of Puget Sound, and went to modeling the Columbia River and the coastal ocean nearby, to modeling the whole region. We’re making the model bigger and more realistic all the time.”

Unlike existing marine forecasts that tell boaters the wind and waves out on the water, this model drops below the water’s surface to predict water temperature, salinity, oxygen, nitrogen, pH, chlorophyll — a sign of biological productivity — and aragonite saturation, the most important factor in shell formation, from the surface down to the seafloor.