Storm Tracker

By KURT LOFT The Tampa Tribune

Published: Nov 27, 2006

TAMPA - Earlier this month, a bow-shaped weather front moved at alarming speed from the Gulf of Mexico, slamming into Pinellas, Pasco and Hillsborough counties with a barrage of lightning and heavy rain.

Meteorologists warned people to avoid bridges, where winds topping 60 mph could force vehicles off the road. The front was fast and furious, but caused no injuries or deaths.

Two days later, a series of vicious, tornado-spawning storms struck four states across the Southeast, killing 12 people and leaving a path of destruction. Authorities say some died with virtually no warning.

Such quickly developing systems are becoming more prominent, scientists say, and their early development needs to be better understood. So researchers are creating a global mosaic of weather patterns that could help them predict the personality of storms not just regionally, but across major parts of the world.

Using a powerful tool called the Tropical Rainfall Measuring Mission satellite, scientists are looking at storms in great detail from most any location. The satellite is the only "rain" radar technology in orbit, one capable of observing in three dimensions the most intense storms and those in the most remote places.

"There are a lot of very useful weather satellites up there, but they don't have radar," says Ed Zipser, a professor of meteorology at the University of Utah and a mission team member. "The more we look at data from this satellite, the more we appreciate what we're learning."

TRMM is the first mission to monitor tropical and subtropical rainfall. Orbiting Earth every 90 minutes from 218 miles up, it tells scientists where it's raining, and how hard it's raining. This information translates into wind patterns, ocean currents, deluges and droughts. One of the satellite's major discoveries was of "skyscraper" storm clouds towering 60,000 feet above the Atlantic, a phenomenon scientists say gives birth to major storms.

When scientists began using satellites to study storms in the 1960s, they found that colder temperatures at the top of clouds were linked to more intense storms. They later realized that average storms could reach very high altitudes, out of the range of most instruments.

Only in the past decade have researchers been able to truly observe the inner structure of intense storms, and TRMM completes the picture. The satellite can dissect a storm system in 3-D: its vertical structure, speed of updrafts, ice content, interior lightning, and lightning flashes per square mile. The satellite acts much like television radar image, except on a global scale.

"Every time you look at a radar loop on television, it's information you can't get from any other source," Zipser says. "Radar is the most valuable single tool in understanding weather because it directly senses [rain] particles. That's what this satellite does. And without it, you could only speculate where the most intense storms are" around the world.

Launched in 1997, TRMM was to have lasted four years before the satellite slowly decayed into the upper atmosphere. But the mission proved so important to studying weather that it got additional funding and a boost to a higher orbit, where it will continue to operate until at least 2009.

Reporter Kurt Loft can be reached at (813) 259-7570 or kloft@tampatrib.com.