Tahlequah Daily Press

February 20, 2014

Thunderstorm classifications


TAHLEQUAH — Classification systems exist for hurricanes and tornadoes, so why not thunderstorms?

There is little enthusiasm among meteorologists to try to classify thunderstorms. They are numerous, take different forms, their intensities change quickly, and they can show the entire range of storm characteristics over their lifetimes.

However, some weather professionals believe a classification system might be helpful to convey the seriousness of a storm to the public, and at least one meteorologist took a stab at it. In 2010, Henry Margusity, senior meteorologist for Accuweather.com, unveiled the “TS Scale.”

The scale rates thunderstorms from a weak TS1 to a dangerous TS5. Average rate of rainfall, maximum wind speeds, hail size, lightning frequency, tornado potential and capacity for damage are factors.

TS1 is a thundershower or weak thunderstorm. Winds do not gust above 25 miles per hour, there are few lightning strikes and no damage occurs.

TS2 is a moderate thunderstorm. Winds can gust up to 40 miles per hour, lighting strikes are occasional and there can be heavy downpours. Slender tree branches may break, but there is very little damage.

TS3 is a heavy thunderstorm. Wind gusts can reach 57 miles per hour, lightning strikes are semi-frequent, and weak tornadoes are possible. Downpours can be heavy enough to flood streets. Minor damage to trees and roofs can occur. Small hail can be present within the downpours.

TS4 is an intense thunderstorm. Gusts can reach 70 miles per hour, stronger tornadoes can occur, lightning strikes are frequent. Wind damage to trees and building can be evident. Medium-sized hail can dent cars or damage crops. Streams and creeks can flood.

TS5 is an extreme storm or supercell. Derecho winds faster than 70 miles an hour are possible. Hail stones are large. Multiple strong tornadoes can be produced. Lightning may be continuous. Flooding and power outages are common. Damage is widespread.