Three researchers at Iowa State are modifying a computer modeling system to increase its ability to make precise weather predictions.

John Iselin, graduate student in mechanical engineering, said computer models are the best scientific tool available for forecasting. He cautioned that even the best models are far from being able to forecast with the accuracy many people would like to have.

Iselin said everything from soil moisture to clouds governs weather patterns.

“Even though the basic principles [of forecasting] are understood, the details are a killer,” said John Prusa, professor of mechanical engineering.

Iselin, Prusa and William Gutowski, professor of atmospheric science, are extensively modifying an existing modeling program. Their angle is to increase its resolution in a given area, Iselin said.

The model is the MM5 used by the National Center for Atmospheric Research. It uses a three-dimensional grid pattern in which mathematical equations interpret the given weather conditions. Iselin said the model can currently handle resolutions of slightly better than 30 kilometers.

Increasing resolution exponentially increases the amount of computing power to run a model, Iselin said. He said the ISU researchers want to increase this resolution in smaller areas, about the size of a county.

Iselin explained that by squeezing the grid points together, the predictions can be more accurate for that area. Because there are some areas in a given region with little happening, the model can borrow grid points from these regions allowing forecasters to focus on a particular weather system.

The researchers are focusing on water vapor in the atmosphere.

“Water vapor … is kind of a wildcard” in weather prediction, Iselin said. He said water vapor determines more than just precipitation.

“It accounts for the energy effects [in the atmosphere]. It takes a lot of energy to evaporate water,” Iselin said. Monitoring these changes can indicate whether a storm is brewing, he said.

The researchers are working on a three-year grant from the National Science Foundation. They are in their second year, but have not yet put the model to use in a real-world situation.

“This is just one aspect of a lot of research that is going on” in the field of atmospheric research, Iselin said.