Wake County Hazard Mitigation Plan - January 2020


Lightning Lightning is measured by the Lightning Activity Level (LAL) scale, created by the National Weather Service to define lightning activity into a specific categorical scale. The LAL is a common parameter that is part of fire weather forecasts nationwide. Table 4.55 – Lightning Activity Level Scale

Lightning Activity Level Scale LAL 1 No thunderstorms

Isolated thunderstorms. Light rain will occasionally reach the ground. Lightning is very infrequent, 1 to 5 cloud to ground lightning strikes in a five minute period Widely scattered thunderstorms. Light to moderate rain will reach the ground. Lightning is infrequent, 6 to 10 cloud to ground strikes in a five minute period Scattered thunderstorms. Moderate rain is commonly produced. Lightning is frequent, 11 to 15 cloud to ground strikes in a five minute period Numerous thunderstorms. Rainfall is moderate to heavy. Lightning is frequent and intense, greater than 15 cloud to ground strikes in a five minute period Dry lightning (same as LAL 3 but without rain). This type of lightning has the potential for extreme fire activity and is normally highlighted in fire weather forecasts with a Red Flag warning






Source: National Weather Service

With the right conditions in place, the entire county is susceptible to each lightning activity level as defined by the LAL. Most lightning strikes cause limited damage to specific structures in a limited area, and cause very few injuries or fatalities, and minimal disruption on quality of life. Impact: 1 – Minor While the total area vulnerable to a lightning strike corresponds to the footprint of a given thunderstorm, a specific lightning strike is usually a localized event and occurs randomly. It should be noted that while lightning is most often affiliated with severe thunderstorms, it may also strike outside of heavy rain and might occur as far as 10 miles away from any rainfall. All of Wake County is uniformly exposed to the threat of lightning. Spatial Extent: 1 – Negligible Hai l The National Weather Service classifies hail by diameter size, and corresponding everyday objects to help relay scope and severity to the population. Table 4.56 indicates the hailstone measurements utilized by the National Weather Service. Table 4.56 – Hailstone Measurement Comparison Chart

Average Diameter

Corresponding Household Object

.25 inch .5 inch .75 inch .875 inch 1.0 inch 1.5 inch 1.75 inch 2.0 inch 2.5 inch 2.75 inch






Ping-pong ball

Golf ball Hen egg

Tennis ball


Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019


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