Greg Carbin knows a lot about severe weather. He's a meteorologist at the storm prediction center, located just south of Oklahoma City in Norman, Okla. In a quiet room on the second floor of the National Weather Service building, meteorologists are standing guard twenty-four hours a day, seven days a week, keeping an eye on weather systems that could unleash violent storms and tornadoes. The meteorologists issue storm watches as needed. For this and more Science Nation, go to...