Is it going to rain in Orange County today? A weather blog by two UC Irvine graduate students can tell you and explain the science behind it.

“We want our readers to learn more about what’s going on outside – not just whether they should bring an umbrella to work,” says Mike Tosca, Earth system science doctoral student and co-creator of the blog,

He and colleague Scott Capps started the site in 2007 after noting a need for weather reports specific to Orange County. Radio and TV forecasts tend to be L.A.-centric. The National Weather Service’s San Diego office issues general information for this area but doesn’t go into detail.

Tosca and Capps base their predictions on the same data used by NWS personnel: satellite images from the National Oceanic & Atmospheric Administration and computer model results. Forecasts posted to the blog are more robust and specialized for Orange County, Tosca says.

“Forecasting is part science and part art form,” he says. “It’s what you think will happen based on what has happened before. Focusing only on Orange County allows us to be more precise than weather agencies that forecast for much larger regions.”

Adds Capps: “We have a pretty good idea of how the atmosphere works, and we know the area very well. All the same, we’re trying to predict chaos, so every once in a while Mother Nature will throw us a curve ball.”

Blog topics range from rain and what causes it to temperature fluctuations, types of wind – including Santa Anas – and weather anomalies.

Entries also address weather-related events. A few weeks after the blog debuted, wildfires broke out across Orange County. Tosca and Capps forecast the dry conditions and predicted which direction smoke plumes would drift. Readership skyrocketed from about 125 hits a day to 700.

“Our blog covered the fires, and people benefited from it,” Capps says.

For both scientists, the interest in weather began in childhood.

Tosca, originally from Connecticut, would graph the height of snow while other kids played in it. “We had very exciting weather – blizzards and hail and heat waves and thunderstorms,” he recalls.

Capps, who grew up in California, was fascinated by rain and clouds. His “toys” included thermometers and wind vanes. “I had to go measure the weather and make observations,” he says.

Today, they complement each other. Capps is focused on specifics, like the exact time frame during which it will rain and to-the-degree temperature predictions. Tosca prefers to look at the broader picture, such as when the next big weather event will occur.

“Scott is into the fine details,” he says. “I gravitate toward epic and catastrophic conditions.”

In the future, Tosca – who studies the long-term, climate-changing effects of fire under UCI Earth system scientists Charles Zender and James Randerson – wants to help shape environmental policy.

Capps got his doctorate from UCI last year and now is a postdoctoral researcher at UCLA specializing in global wind and solar energy.

But their collaboration continues. Says Tosca: “People in Southern California don’t seek to understand the science behind the weather. Our blog intends to change that mentality.”