Severe weather is usually associated with thunderstorms but can refer to any dangerous or destructive weather event. Thunderstorms form due to instability in the atmosphere, and generally require a humid air mass, sufficient daytime heating of the air, interactions between frontal systems, and wind shear (change in wind speed or direction with height).
Severe Thunderstorm Classification
Thunderstorms are classified as “severe” when they produce one or more of the following:
- Wind gusts of 93 kph (58 mph) or greater
- Hailstones with a diameter of at least 2.5 cm (1 inch)
- A tornado
Severe thunderstorms are volatile weather systems that can result in serious damage to business and residential infrastructure. Depending on the strength and weather conditions a thunderstorm produces, prolonged disruptions to transportation and utility networks and business operations are possible. Frequent lightning, strong straight-line winds, flooding downpours, and hail are common during the passage of a severe thunderstorm.
Depending on atmospheric conditions, severe storms could also spawn destructive tornadoes. A tornado typically consists of a funnel-shaped cloud that reaches the ground. Winds associated with a tornado can exceed 322 kph (200 mph). Damage paths can be greater than 1.6 km (one mile) wide and 80 km (50 miles) long.
Business Continuity for Severe Thunderstorms
It is important to know how to effectively prepare for a severe weather event in order to protect life and property and ensure business resiliency following the passage of a storm. This includes conducting a severe thunderstorm hazard assessment ahead of time, categorizing all business assets, developing a severe thunderstorm risk assessment, and practicing site-specific emergency management plans.
Severe Thunderstorm Hazard Assessment
Understand the potential impacts on business operations by conducting a severe thunderstorm hazard assessment ahead of the storm. To do so, list what types of damage may be possible during the passage of a thunderstorm, ensuring all aspects of a storm are considered (hail, flooding, damaging winds, lightning, etc.). Assess the possibility of prolonged disruptions that might continue in the days following a severe thunderstorm (protracted power outages, supply chain disruptions, etc.).
Categorize all business assets that could potentially be exposed to severe thunderstorm activity and assess their degree of vulnerability. Note that thunderstorms (especially those that produce tornadoes) may cause direct losses to physical assets, indirect losses to business function (e.g., loss of production during recovery efforts), and intangible market losses (e.g., missed opportunity to sell to new buyers).
Severe Thunderstorm Risk Assessment
Develop a comprehensive severe thunderstorm risk assessment for your company that speaks to the vulnerability of exposed assets and outlines what are considered tolerable or unacceptable risks.
Use this information to perform a cost-benefit analysis to determine what mitigation measures would be best suited for your company, as well as what options are available to you to ensure business continuity during and after the passage of a storm. The two following tactics can support your risk assessment:
- Create inventories of products, equipment, and vehicles that might need to be moved to a safe location before a severe weather outbreak occurs.
- Ensure that critical datasets are backed up at a secure, offsite facility or through cloud storage.
Emergency Management Planning
Research, create, and practice site-specific emergency management plans to enact during the passage of a severe thunderstorm:
- Reference regional authorities’ local disaster management plans.
- Create a list of emergency contacts (emergency services, essential staff, and suppliers).
- Practice evacuation plans and safe-sheltering protocols to ensure employees are ready to act on short notice.
Always verify the details of your insurance coverage for hazards associated with severe thunderstorms. While your scheme may cover wind damage sustained during a passing thunderstorm, supplementary protection policies may be required for other threats such as flood and hail damage.
For more information on coping with thunderstorms, read our advice sheet on How to Prepare for Thunderstorms.
Click here to see the Enhanced Fujita Scale for tornadoes according to wind speed and damage created.