1.   Both groups are toting a sensor device that might provide valuable information on tornado activity.

2.   Most tornado activity occurs in the Great Plains states, which include Texas, Nebraska and Oklahoma.

3.   Q. What states are within the area of most intense tornado activity?

4.   These graphics are for use as needed and can help illustrate recent stories on tornado activity.

5.   Wurman also noted that a thick deck of cirrus clouds blocking the sun Monday suggested it might not warm upper winds enough for such strong tornado activity.

6.   But maps of tornado activity show the danger area shifts over time.