🌪️ Tornado Simulator

How to Use the Tornado Simulator

Our free interactive tornado simulator uses real US Census Bureau and Statistics Canada population data to model realistic tornado damage anywhere in North America. Here's how to make the most of it.

Quick Start

1. Click anywhere on the map - places a tornado at that location
2. Adjust wind speed slider - changes EF rating from EF0 to EF5
3. Set path length and width - varies the tornado's track
4. View results - fatalities, injuries, damage in dollars

Understanding the Results

Fatalities and Injuries

Estimated using peer-reviewed casualty models:

• Simmons & Sutter (2005) - shelter type effect on fatalities
• Ashley (2007) - nighttime tornado 2.5x lethality multiplier
• NOAA data - ~15:1 injury-to-fatality ratio

Structural Damage

Uses HAZUS-MH structure fragility curves - the same tornado wind engineering data FEMA uses. Different structure types have different failure thresholds:

• Mobile homes: ~70% destruction at 100 mph
• Wood frame: ~55% destruction at 150 mph
• Brick masonry: ~35% destruction at 150 mph
• Reinforced concrete: ~30% destruction at 200 mph

Economic Impact

Combines residential loss, infrastructure damage, vehicle destruction, crop losses, livestock, business interruption, and emergency response costs.

Advanced Features

Multi-Segment Paths

Draw a tornado path with multiple points. The simulator will calculate damage for each segment using local population density from that specific county.

Time of Day

Set the tornado to occur at specific times. Nighttime tornadoes will show significantly higher fatality estimates.

Warning Lead Time

Vary the warning lead time from 0 to 60 minutes. Longer warnings reduce fatalities per Simmons & Sutter research.

Structure Mix

Adjust the housing mix in the tornado path - percent mobile homes, wood frame, brick, concrete. Explore how construction quality affects casualties.

Sub-Vortex Boost

Adds intensity peaks matching multi-vortex tornado behavior. Simulates events like Jarrell 1997 or the 1999 Bridge Creek-Moore F5.

Interpret the Results

Compare your simulated tornado to historical events:

• Under 5 killed: Weak or rural event
• 5-25 killed: Moderate event (e.g., Moore 2013 EF5)
• 25-100 killed: Major disaster (e.g., Tuscaloosa 2011)
• 100+ killed: Historic catastrophe (e.g., Joplin 2011)

Use Cases

• Emergency planners - visualize damage scenarios for exercises
• Teachers and students - understand tornado meteorology
• Insurance professionals - model exposure to specific tornado scenarios
• Homeowners - understand what an EF3 vs EF5 could do to your neighborhood
• Storm chasers and meteorologists - explore scenario space

Data Sources

Our simulator uses:

• US Census Bureau ACS 5-Year (2022) - 3,143 US counties
• Statistics Canada 2021 Census - 288 census divisions
• HAZUS-MH - FEMA structural fragility data
• Simmons & Sutter (2005) - casualty models
• Ashley (2007) - nighttime lethality
• NOAA Storm Data - historical event data

What the Simulator Won't Tell You

• Specific individual outcomes - it's a statistical estimate
• Exact building types in your path
• Real-time weather forecasts
• Actual tornado predictions

Do not use the simulator as a substitute for real NWS tornado warnings. If a warning is issued for your area, seek shelter immediately regardless of what any simulator says.

Educational Applications

Teachers using the simulator: consider having students simulate:

• The Joplin 2011 tornado at Joplin's coordinates
• The Bridge Creek-Moore 1999 tornado at Moore
• Multiple locations to compare damage differences by geography
• Different EF ratings on the same location

→ Simulate a tornado on our map