How are tornadoes measured? NWS uses the improved Fujita scale


I’m sure you’ve heard people say, “The National Weather Service will survey the area for damage before determining if the tornado was EF 1, 2, 3,” and so on. But what are they looking for to know the intensity of a tornado?

Let’s start with EF0 with winds of 65 to 85 mph.

This is considered minor damage and about half of all tornadoes are determined EF0. With an EF0, they look for broken tree branches, peeling surfaces of some roofs, damage to gutters or siding, and pushed on trees with shallow roots. Additionally, tornadoes that remain in open fields with no reported damage are EF0.

Moving on to EF1 tornadoes with 86-110 mph winds or moderate damage.

About 30% of reported tornadoes fall into this category. Consequences include severely stripped roofs, shattered windows/glass, ripped exterior doors, and overturned or badly damaged mobile homes. The March 21, 2022 tornadoes in Jarrell and Giddings are in this category (SO FAR).

EF2 tornadoes are suspected in Round Rock, Granger, Elgin and Kingsbury.

EF2 winds are 111-135 mph / extensive damage. About 10% of tornadoes are EF2. Damage includes roofs ripped off homes, mobile homes totaled, large trees snapped or uprooted, and vehicles being lifted off the ground as we saw in Bastrop County.

EF3 – Severe damage with winds of 136-165 mph.

About 3.5% of tornadoes fall into this category. The investigative team is looking for full stories of homes being ripped out, damage to tall buildings, tree bark stripped, heavy cars being lifted and thrown, and trains overturned.

EF4 – Extreme to near total destruction – winds are 166-200 mph. About 0.7% of tornadoes fall into this category. This is where heavy cars are thrown long distances, well-built houses and full-frame houses are fully leveled.

And finally, the deadliest and rarest EF5 tornado with winds over 200 miles per hour, accounts for less than 0.1% of tornado reports. It falls under the massive damage category.

The aftermath includes substantial wood-frame houses being lifted from their foundations and swept away. Steel-reinforced concrete structures are badly damaged and high-rise buildings suffer from severe structural distortions.

In 1997, Jarrell in Williamson County faced an EF5.

The peak of tornado season in the Austin area is May, so it’s time to make sure you and your family have a plan.

Quickly track your local forecast for the Austin area with the free FOX 7 WAPP. The design gives you 7-day radar, hourly and weather information just by scrolling. Our weather alerts will warn you early and help you stay safe during storms.

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