The Android phone in your pocket could help scientists do a better job of predicting the weather – exactly where you are.

Atmospheric scientists are working with an app developer to take air pressure information that is already being collected from thousands of Android phones and feed it into sophisticated new climate models. If they get enough buy-in from Android owners, you may be able to receive warning hours in advance about thunderstorms and tornadoes coming to your precise location with far more certainty than you can today.

“The first I heard about these [Android] pressure sensors I said, ‘Oh my god, this could be a huge game changer,'" said Cliff Mass, an atmospheric scientist at the University of Washington. "My vision is someone needs to collect all these observations across the country – we could have a million an hour – and use that to radically improve weather prediction."

With Android 3.0, Google added support for atmospheric sensors into the operating system. The point wasn't to enable barometer apps, although there are many of those now, but to help with location finding. Atmospheric pressure changes with altitude, so comparing the pressure reading collected from a phone against readings taken from nearby stationary weather stations will help pinpoint the altitude of the phone.

Mass and his colleagues at UW were on the lookout for sources of atmospheric pressure data to include in their models in hopes of improving weather prediction. "The idea is to use the pressure to figure out a high-resolution structure of the atmosphere before a thunderstorm develops or becomes intense," he said.

Mass calls atmospheric pressure, which is a measure of the weight of the atmosphere above you, a "uniquely valuable observation…. It's the only surface parameter that expresses the deep atmosphere," Mass said.

Right now forecasters can vaguely tell you that there’s a chance of thunderstorms the next day. But if researchers can incorporate a large volume of pressure readings into climate models to define features associated with severe weather events, they can begin predicting when a severe storm will hit a specific part of a city up to six hours in advance. “You couldn’t do that now with any skill,” Mass said.

The pressure data currently available to Mass and his colleagues is limited in both quality and volume. The orders of magnitude more atmospheric pressure data they could collect from Android phones could make a big difference. Mass sees the potential data from Android phones as "an extraordinarily high resolution observation network over the land."

Pressure sensors are well suited to mobile phones. By comparison, temperature sensors are impacted by wind, direct sunlight, and shade or whether the sensor is indoors or out. "There are all these exposure issues for all other parameters except pressure," Mass said.

Mass has been working with Jacob Sheehy and Phil Jones, the developers of an Android app called PressureNet. They say it's the only barometer app on Android that not only shows users the pressure reading in their location but collects the data and shares it back to all users. The app lets users zoom into a location on a map to see a graph of the collected readings from that region.

When Mass first talked to Sheehy and Jones earlier this year, they were collecting only around 80 data points an hour worldwide. "He said, 'great, but you need to grow bigger before your data is useful'," Sheehy said.

Then Hurricane Sandy hit and Sheehy and Jones did some marketing. Downloads of the app grew to around 14,000 worldwide, resulting in around 3,000 to 4,000 readings per hour, which Mass says is starting to be useful.

But it's still nowhere near a million, pointing out just one of a few challenges this group faces. They'll need to convince users of the Galaxy Nexus, Nexus 4, Nexus 10, Galaxy S3 and Galaxy Note to get the app. These and a few others are the only phones and tablets that currently have atmospheric sensors.

Also, presumably most users of the app spend most of their time on land, limiting the types of weather conditions researchers might be able to better predict. Anticipating hurricanes, which form over oceans, won't get any better. But Mass thinks they may be able to significantly improve predictions of thunderstorms and tornadoes over land. Ultimately, the idea is that the forecasts could feed back into an app that accurately shows when and where storms are coming.

There are hurdles before Mass can even get the data. Sheehy and Jones have only just started looking into privacy implications. Because pressure changes with elevation, it helps to tie the pressure data to a phone in order to determine if the pressure is in fact changing or if the reading is changing because the phone user has moved up a hill or an elevator. They envision different levels of sharing that end users can choose from, including sharing only with academic researchers or in any way the developers see fit.

In the meantime, aware that some people may be interested in the data who don't have phones with sensors, Sheehy and Jones have built a web site that anyone can visit to see the collected data. It's still under development and they're currently manually adding data but it's a taste of the kind of data that's possible to collect from Android phones.