WILL SEBERGER/Arizona Summer Wildcat A monsoon storm front rolls in over Arizona Stadium on Saturday night. Balls of lightning lit up the night sky.

Just over a week before the weekend storms crawled over Tucson, on July 3 ÷ the date on which many had predicted the season would begin, researchers in the UA department of atmospheric sciences were getting their own taste of the monsoon season.

That day a team of researchers made the final contribution to a project that they said will help both weather watchers and concerned citizens better understand Arizona's rainy season. The project is based on the use of a number of weather sensors, called Global Positioning System (GPS) sensors that collect humidity data and could thereby help people prepare for dangerous monsoon thunderstorms.

"It's cutting edge," said Eric Pytlak, a science positions officer at the National Weather Service in Tucson.

With six operational GPS sensors spread throughout Southern Arizona and Northern Mexico, the University of Arizona is part of an international network, "SuomiNet," designed to make National Weather Service forecasts more accurate and timelier.

"GPS sensor data will be of greatest benefit helping the National Weather Service better predict where storms are moving on an hourly time scale," Pytlak said.

"Imagine, with the balloon sensors we use now, we get readings twice a day. This (real-time) sensor technology takes measurements every hour," Pytlak said, adding that the ability to collect data more often will drastically improve meteorologists' ability to track storms and model weather trends.

He also emphasized the importance of early preparation in dealing with monsoon thunderstorms, like those this weekend.

On Friday night, the dew point average rose above 54 degrees for the third day in a row, marking the official start of the monsoon season.

The ensuing thunderstorms that rolled over the city throughout the weekend were accompanied by high winds that damaged power lines and left over 5,000 Tucson Electric Power customers without electricity, TEP officials said.

The storms also left many Tucsonans with problems ranging from downed trees and utility posts to damaged homes and vehicles and near-zero visibility.

Although the new technology cannot prevent all the damage that results from monsoon storms, it could help give people more time to prepare, Pytlak said.

Under the UA system, 24 GPS satellites beam signals to receivers throughout North America to collect humidity data. Because water molecules in the air slow the satellite signal, weather service officials can determine the amount of moisture in the air by measuring signal lag. The more water vapor in the air, the slower the signal travels.

With sites already in Hermosillo, Rocky Point (Puerto Pe–asco) Phoenix, Douglas, and Tucson, researchers plan to establish more sights and expand the Suomni network.

"We're currently proposing to add 10 more sensors for the UA," said Andrea N. Hahmann, an atmospheric physics research assistant professor who is helping coordinate the research.

According to the National Weather Service's website, the storms are expected to continue every afternoon or evening until at least Tuesday.

For more information visit www.wrh.noaa.gov.