An isolated tornado is a term used by meteorologists to warn the public that an occasional tornado is possible with approaching storms. When this term is used, forecasters do not expect a widespread outbreak of tornadoes to occur. A tornado watch may or not be issued when isolated tornadoes are mentioned.
Any severe storm is capable of producing a tornado with no warning, even when weather conditions are not favorable for the development of tornadoes. In order to keep the public safe from rapidly changing conditions, meteorologists will sometimes mention the possibility of an isolated tornado anytime severe weather is expected.
A tornado is a column of air that rotates violently, and with winds sometimes in excess of 300 mph, it is considered the most destructive localized weather phenomenon. Most tornadoes form inside rotating supercell storms, which are severe storms that produce hail, high winds, and heavy rain. In the United States, a portion of the Midwest is called "Tornado Alley" because of the numerous tornadoes that occur in this area. Although tornadoes can occur anywhere and anytime of the year, the peak season is in May for North America. The more vigorous and complex a storm system is, the more tornadoes it typically produces.