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Convective Storm Risk: Understanding Your Unique Vulnerability

Extreme loads and structural risk

Hailstorms, Tornadoes, Thunderstorms - What are Convective Storms?

Gaining a Holistic View of Severe Weather Risk

A universal threat that affects organizations worldwide, especially as climate change progresses, is convective storm risk. Although severe weather can be difficult to plan for, it is crucial to evaluate potential damage and plan appropriately. So, what is a convective storm? It is the collective name for severe thunderstorms, including heavy rainfall, strong winds, hail and tornadoes. Depending on your location around the world, the intensity of these storms differs.

North America

Over 900 tornadoes occur on average each year in the United States, with a large proportion occurring in the “Tornado Belt” of the Central Plains (Texas to Nebraska) during spring.


Extreme flooding and hailstorms pose a threat to the UK and Mainland Europe, with around 250 tornadoes occurring each year and increased wind events in the last 50 years.


In Australia, the convective storm season runs between September and March. Primary threats include severe hailstorms, although more severe events like tornadoes are still common across the region.

Differentiating Your Risk: Tornadoes vs. Hurricanes

Quantifying the type of severe weather your organization may encounter will shape your risk management approach to convective storms. While on the surface, tornadoes and hurricanes may appear to be very similar (both are cyclic winds rotating based on the rotation of the earth), they are categorized by very different factors.

Formation of a Tornado

Stages of Development  

Formation: Hurricanes and tornadoes are alike in basic ways. Both produce powerful, swirling winds — and both can leave a path of death and destruction. However, tornadoes tend to be a smaller scale risk. They usually form over land and are between 1 and 1.5 miles in diameter. They are created when high-volume winds mix warm moist air with dry cold air. In comparison, hurricanes form over the water and can be between 60 and 1000 miles in diameter. They occur when ocean water rises and reaches 76°F (26.5°C); then, areas of intense low-pressure form, pulling in air that starts spinning.

Duration: Hurricanes can last from days to weeks, while tornadoes live much shorter lives—anywhere from five minutes to a couple of hours.

Aftermath: The destruction of a hurricane can be tens of miles long, with the majority of damaged to structures caused by rainfall, flooding and wind. In contrast, the majority of damage from tornadoes is caused by severe wind damage. There have been reports of entire buildings transported from one location to another. Tornadoes are accompanied by hailstorms 85% of the time as they form under similar conditions.

Hail Hazard and Damage

Hail forms in the upper regions of actively growing convective storms. The strong convective updrafts in a developing thunderstorm can reach 100 mph (160 kph), bringing large amounts of moisture and debris into the storm. The debris collect water, creating tiny raindrops that eventually freeze. When the weight of the growing ice can no longer be supported by the storm’s updraft, the ice crystals (known as hail) descend, partially melting before hitting the ground.

Most property damage from hail occurs only when hailstones are 0.75 inches (19 millimeters) or more in diameter. Extremely severe hailstones can damage cars, destroy roofs, break windows, and seriously injure animals and humans.

How to Implement a Risk Reduction Program

A robust Risk Reduction Program can enhance operational resilience and help organizations to fully understand and mitigate against their natural hazards risk. ABS Group's Risk Reduction Program is a 3-phase approach that supports and guides clients in managing their unique risk. 

Step 1: Hazard Exposure  Identification

Hazard Exposure Identification involves utilizing hazard mapping tools and Catastrophe (CAT) Modeling to provide financial loss estimates for property damage and business interruption for single-site and aggregate losses. The hazard mapping provides a categorization of the hazard risk in an easy-to-understand high, moderate or low-risk format. It can include multiple natural hazards to help you understand the full extent of your facility's exposure. 

Step 2: Facility Vulnerability

Facility Vulnerability helps you to understand the critical vulnerabilities of your facility. From supply chain reviews to facility vulnerability audits, understanding how your organization is vulnerable to natural hazards will be critical when establishing your risk mitigation strategies. A cost/benefit analysis can also help you to understand how certain changes to your facility could provide a significant cost saving in the case of an event. 

Step 3: Risk Mitigation

Next, it is time to put the mitigation plans in place. This involves four (4) key stages: 



Through detailed engineering design, independent design reviews and guidance document reviews, a treatment plan to lower the established risk can be developed.


Managing your risk through training of personnel, emergency response planning and business continuity planning can help an organization to keep the risk low. 


By providing your insurers with a Facility Vulnerability Audit Output report, you can help to make sure your coverage is adequate.


By utilizing the hazard mapping provided in Stage 1, you can remove the risk completely by performing a CAPEX review to relocate your facility to an area with significantly reduced risk. 

Why Choose ABS Group to Manage Your Natural Hazards Risk? 

Convective storms pose a risk globally, with severe winds, hailstorms and flooding threatening businesses and communities. While the risk of tornadoes is significantly higher in North America, convective storms have a worldwide impact and must be prepared for. To understand your facility's risk contact our Natural Hazards Team for risk mitigation, vulnerability assessments and supply chain assessments to help you and your insurers have the confidence that your organization has appropriate measures in place to protect your staff and assets.

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