POSTED: 01:30 a.m. HST, Jun 09, 2011
Question: Recently, there have been lots of thunder and lightning over our state. I read something that really amazed me — that the number of lightning strikes to the ground was in the thousands. Is that true? If so, why hasn’t there been more damage?
Answer: Those amazing lightning figures need to be explained and put in perspective.
For example, the estimated 40,000 lightning “strikes” reported over the state in a 30-hour period May 2 to 3 weren’t all strikes or hits and they occurred within a “domain” that encompasses a wide area around the Hawaiian Islands. They weren’t necessarily even near land. (You can see the area covered in the counts as a rectangular map posted on weather.gov/hawaii.)
The proper term when referring to the numbers is “lightning counts,” said Ray Tanabe, meteorologist-in-charge at the National Weather Service’s forecast office in Honolulu. That refers to “all occurrences of lightning,” not just hits.
The lightning counts being reported are “a mix of cloud-to-ground and in-cloud lightning, and (the data service is) telling us there was probably significantly more lightning than that,” said Robert Ballard, science and operations officer for the National Weather Service in Honolulu. “From what I'm told, there’s no way of knowing what percentage of those numbers were cloud-to-ground strikes that hit land.”
He added, “I would say most of those were over the water because we are fairly small targets.”
Ballard explained that, locally, forecasters have been receiving data from the World Wide Lightning Location Network for several years, but only this year came up “with a script where we can pull the data” on a six-hour delayed basis. “Previously, we never had a good way to measure lightning counts.”
Without historical data, it’s hard to compare the number of lightning counts to years past. But although the number of lightning occurrences seems astronomical, the number in fact is believed to be much higher.
Citing Robert Holzworth, director of the World Wide Lightning Location Network at the University of Washington (see http://wwlln.net/), Ballard said the network detects only a fraction of all lightning and the precise number is unknown. “Globally, he estimated that the network picks up about
10 percent of all lightning, but that number may not be accurate for the region around Hawaii specifically,” Ballard said.
While it’s not possible to say definitively that there is a lot more lightning activity here than in years past, Ballard said forecasters do know that the number of thunderstorm days in Honolulu is “well above normal” this year.
“The long-term climate record for Honolulu Airport shows about seven thunderstorm days in a calendar year on average,” he said. Since Nov. 1, there already have been 28 thunderstorm days at the airport.
WHAT TO DO IN AN ELECTRICAL STORM
Because lightning doesn’t happen often in Hawaii, most people don’t know what to do.
“It’s not common here, but that doesn’t make it less deadly,” said Robert Ballard, science and operations officer for the National Weather Service in Honolulu.
Basically, as soon as you hear thunder, head indoors.
“We really want to stress … it does not have to be raining in your location to be struck by lightning,” Ballard warns. “Lightning can travel a long way through the ground. Lightning can travel an incredibly long way along metal objects — we’re talking miles. It is not safe to be outside during a thunderstorm.”
For more safety tips and information about lightning, go to www.lightningsafety.noaa.gov/. June 19-25 has been designated Lightning Safety Week by the weather service.
Write to “Kokua Line” at Honolulu Star-Advertiser, 7 Waterfront Plaza, Suite 210, 500 Ala Moana Blvd., Honolulu 96813; call 529-4773; fax 529-4750; or email firstname.lastname@example.org.