It is difficult to nearly impossible to predict where and whether or not a tornado will strike. All forecasters can do is warn people when conditions are right for tornadoes to form, or, if one is sighted, to tell people to take shelter. Meteorologists look for tornadic thunderstorms that have strong indications of wind shear, lift, moisture, and instability. No one type of weather pattern leads to tornado formation, which greatly complicates forecasting efforts. To aid in their predictions, meteorologists use all sorts of technology, including weather balloons, Doppler radar, satellites, data from weather stations, lightning strike plots, and computer modeling.