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Mapping a “bolt from the blue”: Behind a rogue lightning flash near Silver Spring from a storm in Falls Church

Depiction of a “bolt from the blue” that occurred at 9:35 pm on June 25, 2014 in Washington, D.C. The lightning photograph captures only a small portion of a much larger flash as observed by the <a href="">Washington D.C. Lightning Mapping Array (DCLMA</a> . Note the inserted lightning photo is not to the exact scale and perspective of the plot.)

On the evening of June 25, at 9:35 p.m, a lightning flash originated 27,000 feet above Falls Church, Va., within a line of developing thunderstorms. The flash propagated in all directions, spanning an area from Tysons Corner through Baileys Crossroads and Glen Echo to Takoma Park.

3D animation of the lightning flash from June 25, 2014 at 9:35 p.m.  (Scott Rudlosky)

This expansive flash covered nearly 150 square miles, and at its highest point, reached over 51,500 feet above ground. Incredibly, the flash extended and struck the ground as far away as Silver Spring, Maryland, nearly 10 miles northeast of its origin, well outside of the parent thunderstorm.

This spectacular lightning flash is what’s often referred to as a “bolt from the blue”. In its truest form, a bolt from the blue travels from the cloud edge through clear air only before striking ground (often more than 20 miles from the parent storm). Many times, these flashes travel through old decaying storm clouds that have some residual electric charge, before striking ground.

The exact reason why a lightning channel follows its particular path is not known. Scientists are continually working to better understand how particle collisions in clouds ultimately result in the many varieties of lightning flashes.

A previous post following the June 29, 2012 derecho describes our efforts to document lightning flashes using both photographs and data from the Washington D.C. Lightning Mapping Array (DCLMA). This combination again provided tremendous insights into a scientifically interesting lightning flash in D.C.

While the June 25, 2014 lightning viewed from D.C. that struck ground in Silver Spring may not have been a true bolt from the blue since some clouds were overhead, the surprise and danger are equal. The common attribute shared by these flashes is that they exit the side of storms and strike ground outside the heaviest rain and away from the most obvious threat area.

Although these flashes may seem random and unpredictable, the signs of lightning (rain, clouds, distant thunder) are almost always present before it strikes. In many places, the first step to protecting yourself from lightning is to notice the growing cumulus cloud towers, especially if storms are in the forecast. If conditions are ripe, a small cloud can grow to a lightning producing storm in under 30 minutes.

Education and awareness are the keys to protecting people and property from lightning. Be an advocate and speak up if conditions seem unsafe, you do not need to wait for an authority figure to take action. Remember, “When Thunder Roars, Go Indoors”.

“Bolts from the blue” originate like more traditional lightning flashes, but are constricted by strong charge layers and forced outside the parent storm. Lightning Mapping Arrays (LMA) and new dual-polarimetric radar technology will be used to further analyze this type of lightning in search of new insights and information.

The story behind capturing the bolt

With storms in the forecast, I arrived at the Jefferson Memorial at 9:30 p.m. on June 25 and began running my camera with repetitive 13-second timed exposures. I was hoping to photograph a lightning bolt striking ahead of the incoming storm.

A few minutes before the lightning strike occurred, a fast-moving shower dropped just enough rain to wet the earth around the Tidal Basin.  Big raindrops fell for about five minutes but the shower did not produce lightning.  The sky cleared as the shower moved to the east.

At 9:35 p.m., a lightning bolt – that we ultimately learned struck the ground near Silver Spring – lit up the sky over Washington, D.C.  The single bolt was visible in the northern sky.  The tourists in the Jefferson Memorial cheered loudly when they saw the flash.  Many other tourists that were strolling around the Tidal Basin were probably surprised by the sudden lightning flash as it was a warm, pleasant evening with a patch of clear skies above.

When the sky lit up with the lightning flash, I was just as surprised as the cheering tourists at the Jefferson Memorial.  I was also quite pleased that the lightning lined up with the Washington Monument.  With 360 degrees of horizon in view, lightning doesn’t often strike behind a D.C. landmark for a good photograph.  After ten years of photographing lightning in Washington, I have missed countless shots.

Thunder soon followed the lightning strike.  It was the first thunder of the evening in Washington.  To the west, there were strobes of light on the horizon but thunder was not audible with the distant flashes.

On the previous day, I met Scott Rudlosky Ph.D at a NOAA lightning safety workshop hosted by University of Maryland.  We had a long discussion about the “bolt from the blue” during the workshop. Scott also presented the work we did together when we mapped the 2012 derecho lightning bol.  It was one of my favorite articles.

So, when I began photographing that evening, I had “bolts from the blue” still fresh in my mind from the discussions with Scott.  That was part of the reason I started shooting timed exposures early, before the storm moved in Washington, D.C.  I was hopeful, but I had low expectations for photographing the rare type of lightning.

After the strike, I quickly checked my camera and saw that the lightning was properly exposed.  I selected an F-stop of 6.3 with ISO 50 at 13 seconds which worked well for that particular lightning flash.

I immediately wondered if the lightning originated from the distant thunderstorm to the west or if another thunderstorm cell was developing nearby.  No other visible lightning occurred for many minutes after the strike and it took about 15 to 20 minutes for the thunderstorms to the west to arrive in D.C. with frequent lightning.  I photographed one other close lightning strike during the thunderstorm.

The next day, I emailed my first lightning photo with its time stamp to Scott Rudlosky for his analysis.  I was curious to see if  Scott could map the lightning flash to determine where it originated.  I also put together a photo article for the Capital Weather Gang with several other storm photos that were taken the same day.

Soon after my photo article was posted on CWG, there was an interesting comment.  It was from a reader named Gull who described the storm’s lightning as follows:

Had 2 very loud instantaneous cracks of thunder in Silver Spring last night, plus about 4 or 5 that were within a mile or so in distance. One of them was an out of the blue (well, black) strike, as it came about 15 minutes before the storms really arrived.

When I read the comment, I thought that the early-arriving bolt Gull described in the comment was the same bolt I photographed.  From the photo, it looked possible that it landed near Silver Spring but I was uncertain.

A couple days later, when Scott sent me his lightning analysis, I learned that the bolt I photographed hit about a mile south of Silver Spring.  Yes, it was the same bolt that Gull heard and posted in the comment.  It was indeed a bolt from the blue (well, black).