Vaisala, which monitors lightning activity around the world, has released the Top 10 lightning flash days in 2014 as detected by its National Lightning Detection Network (NLDN) and Global Lightning Dataset GLD360 network.
Top 10 Cloud-to-Ground Lightning Days in Contiguous U.S.
1. June 19: 361,927 cloud-to-ground flashes (Top state: South Dakota)
2. June 18: 357,318 cloud-to-ground flashes (Top state: South Dakota)
3. June 5: 297,052 cloud-to-ground flashes (Top state: Tennessee)
4. July 27: 291,615 cloud-to-ground flashes (Top state: Kentucky)
5. April 28: 284,409 cloud-to-ground flashes (Top state: Mississippi)
6. July 23: 277,924 cloud-to-ground flashes (Top state: Arkansas)
7. Sept. 2: 271,161 cloud-to-ground flashes (Top state: Kansas)
8. July 14: 267,279 cloud-to-ground flashes (Top state: Tennessee)
9. May 12: 262,927 cloud-to-ground flashes (Top state: Texas)
10. July 15: 260,477 cloud-to-ground flashes (Top state: Texas)
As might be expected in the U.S., the top days are mainly in the summer months, but the spring months of April and May appear this year, and another in early September. Previous Vaisala studies have found that two-thirds of the contiguous U.S. cloud-to-ground lightning flashes occur in June, July and August.
Global Top 10 Days for Lightning
1. Sept. 2: 4,315,259 strokes
2. April 30: 4,211,041 strokes
3. April 29: 4,039,212 strokes
4. Oct. 2: 3,676,378 strokes
5. Sept. 20: 3,634,461 strokes
6. Aug. 30: 3,627,466 strokes
7. April 28: 3,571,362 strokes
8. May 27: 3,550,073 strokes
9. July 3: 3,543,899 strokes
10. July 2: 3,496,652 strokes
Around the world, all of the top 10 days are in the Northern Hemisphere summer and the months shortly before and afterward. This is to be expected because of its much larger land mass compared with the Southern Hemisphere. In addition, only two days for the world are the same as for the U.S., which shows how diverse thunderstorm systems occur at any time around the world.
Although the specific days and locations of the top 10 lightning days change annually, the total number of cloud-to-ground flashes remains between 20 and 25 million per year over the contiguous U.S. Having an increased understanding of when, where and how much lightning occurs has been coincident with a gradual reduction in lightning fatalities and injuries in the U.S.
The NLDN is a precision lightning network owned and operated by Vaisala and detects in-cloud and cloud-to-ground lightning throughout the U.S. Both the GLD360 and NLDN provide information to agencies such as the National Weather Service and the Federal Aviation Administration for forecasting, safety and to support operational decision-making.
GLD360 detects lightning around the world with very long-range sensors that allow continuous coverage over land and oceans.