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Tornadoes in Washington – Should You Batten Down the Hatches?

April 25, 2014

Tornado

When most people think of tornadoes and where they occur, the Midwest usually comes to mind, not somewhere like Washington where our biggest weather woes tend to be flooding and wind storms – and those occasional times in January when it snows three inches and our entire hilly city shuts down. But sarcasm aside, tornadoes do occur in Washington and have even been known to cause property damage and loss of life.

In fact 2013 saw a few tornado events, although nothing that can compare to the twisters in places like Missouri or Kansas. On March 21st, 2013, an EF-0 tornado struck a barn in Clark County, and on September 30th, 2013, an EF-1 tornado struck near Puyallup, knocking rail cars off the track and doing significant damage to a door manufacturing business in the area.

EF-0 and EF-1 tornadoes are not uncommon in Washington; in fact almost one twister has touched down every year for the past 3 years.

What do EF-0 and EF-1 mean and are they the same as funnel clouds? Historically tornados were judged by something called the Fujita Scale (F-scale). The F-scale rated tornadoes based on damage and estimated wind speeds. When a tornado struck, scientists would look at the damage caused and rate it on a scale of 0–5.

The Fujita Scale, developed in 1971 by T. Theodore Fujita at the University of Chicago, read as such (from NOAA.gov):

Scale

Wind Estimate (MPH) Typical Damage
F0 <73 Light damage. Some damage to chimneys; branches broken off of trees; shallow-rooted trees knocked over, sign boards damaged.
F1 73–112 Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads
F2 113–157 Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
F3 158–206 Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.
F4 207–260 Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
F5 261–318

Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.

As NOAA notes, these wind speeds are not to be taken literally; they are estimates of wind speed based on damage that has occurred.

On February 1, 2007, the United States adopted an enhanced Fujita scale (EF-scale) to help more accurately determine damage from a tornado. It uses the speed from 3-second gusts of wind, a more detailed indicator of damage, and a scale to indicate the degree of damage caused. To learn more about the EF-scale, check out this fact sheet from NOAA.

How does a tornado differ from a funnel cloud? Tornadoes are simply funnel clouds that touch the ground. Reports of funnel clouds occur more often in Washington State, but there are fewer tornadoes because these clouds don’t generally get down to ground level.

Tornado damage may be covered in your insurance policy, so it’s important to check with your agent, especially if you live in a more tornado-prone area!

Article by: Kristen Skinner

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