Outdoor FunWeather 101

How To Measure Wind Damage From Tornadoes, Hurricanes & Other Storms

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By Joshua

Wind damage – its dramatic impacts are sometimes the first images we see following a hurricane, tornado, or strong thunderstorm.

Fortunately, meteorologists are doing an incredible job at improving forecasting methods so homeowners, municipal leaders, and emergency officials can prepare for storms ahead of time and potentially prevent wind damage.

In my Florida city, for example, hurricane season always means city and county code enforcement officials are out in strong numbers inspecting buildings for weak spots, trimming down branches near utility lines, and reminding the public to upgrade their windows, entry doors, and garage doors to more wind-resistant varieties.

Virtually all cities in Florida and many counties outside of the Sunshine State are doing their best to comply with Miami-Dade County wind codes, which mandate some of the toughest hurricane wind codes in the world.

What makes wind codes from a county located in the southeast tip of Florida so special?

Well, in order for your home to pass those county codes, it must be able to withstand a 9-pound 2×4 being hurtled toward it at 30 MPH. Then, after surviving the yellow pine missile attack, your home must survive being a pelting from steel ball bearings traveling at a staggering 90 MPH.

Measuring Wind Damage

There are several different wind scales that are commonly used to measure wind damage. Determining which of these scales to use in contingent on what type of wind damage you need to measure.

For example, there is the Beaufort Wind Scale, which categorizes wind damage in incremental ranges up to hurricane force winds.

Then there is the hurricane category scale, called the Saffir-Simpson Hurricane Wind Scale. This scale divides hurricanes into five different categories, based on the highest average sustained wind speed for a minute of observed time.

Also, there is the Enhanced Fujita Tornado Damage Scale. What this does is categorize tornado wind strength based on observations of damage.

We’ll take a closer look at these 3 wind scales below.

Beaufort Wind Damage Scale

In 1805, Sir Francis Beaufort devised a wind scale that determines approximate wind speeds based on observations of wind effects.

Here is the Beaufort wind scale:

  • Less than 1 MPH wind: calm, sea surface is smooth and smoke rises vertically
  • 1 to 3 MPH winds: light air, smoke drifts slowly with the breeze and indicates wind direction
  • 4 to 7 MPH winds: light breeze, you can feel the wind on your face and hear leaves rustle
  • 8 to 13 MPH winds: gentle breeze, smoke moves horizontally and small branches sway
  • 14 to 19 MPH winds: moderate, dust or sand on the ground will move and large branches will sway
  • 20 to 25 MPH winds: fresh breeze, surface waves form and small trees will sway
  • 26 to 31 MPH winds: strong breeze, trees bend with force and wind will whistle around utility wires
  • 32 to 38 MPH winds: moderate gale, large trees sway and moderate sea spray forms
  • 39 to 46 MPH winds: fresh gale, twigs break from trees and streaks of foam appear on the ocean
  • 47 to 55 MPH winds: strong gale, branches break from trees
  • 56 to 64 MPH winds: whole gale, trees are uprooted and the sea appears white
  • 65 to 74 MPH winds: storm, widespread damage occurs
  • More than 75 MPH winds: hurricane, structural damage occurs on land and strong waves form in the sea

Saffir-Simpson Hurricane Wind Damage Scale

Hurricanes are among the greatest shows of Mother Nature’s strength and, during the unleashing of their wrath, can exert tremendous power that can wash away beaches and barrier islands, level towns, and devastate whole regions of a nation.

The hurricane scale, devised in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson, divides hurricanes into 5 strength categories based on wind speed.

Hurricane categories include:

  • Category 1 Hurricane: 74 to 95 MPH winds
  • Category 2 Hurricane: 96 to 110 MPH winds
  • Category 3 Hurricane: 111 to 129 MPH  winds
  • Category 4 Hurricane: 130 to 156 MPH winds
  • Category 5 Hurricane: More than 157 MPH winds

Enhanced Fujita Tornado Wind Damage Scale

Tetsuya Theodore “Ted” Fujita, aka Mr. Tornado, introduced the Fujita scale in 1971. Measuring wind speed and correlating wind speed to wind damage, the Fujita scale is in widespread use around the world, not to mention the central United States, which is notoriously referred to as Tornado Alley.

The Fujita scale has been modified a few times over the decades, most recently in 2007, when attempts were made to more accurately match wind speeds to the severity of wind damage. Since the adoption of the new wind measurement standards, the popular wind scale has been renamed the Enhanced Fujita Scale.

The current wind speed standards are as follows:

  • F0 Tornado – 40 to 72 MPH winds: light damage including branches broken off trees and sign boards pushed over
  • F1 Tornado – 73 to 112 MPH winds: moderate damage will occur, such as mobile homes could be pushed off foundations, cars may shoved off roads, and garages might sustain severe damage
  • F2 Tornado – 113 to 157 MPH winds: significant damage, including roofs torn off homes, large trees are snapped or uprooted, high-rise windows may be broken, and mobile homes could be demolished
  • F3 Tornado – 158 to 206 MPH winds: severe damage might include roofs and walls will torn off homes, trains could be overturned, and large cars could be lifted off the ground
  • F4 Tornado – 207 to 260 MPH winds: devastating damage will occur, including the destruction of well-constructed homes and cars will become airborne and thrown like missiles
  • F5 Tornado – 261 to 318 MPH winds: affected areas will sustain incredible damage; frame houses will be lifted off their foundations and disintegrate, cars could be flung more than 100 yards, trees will be stripped of their bark, and even steel-reinforced concrete structures will be damaged