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Meteorologists remember the June 2012 Mid-Atlantic derecho

The derecho remains one of the most widespread and ruinous severe thunderstorms to hit the region

A large tree limb lies near the Capitol across from the Supreme Court after a powerful storm swept the D.C. region on June 29, 2012. (Manuel Balce Ceneta/AP)
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A decade has passed since one of the most memorable storm events in Washington weather history: the June 29, 2012, derecho. The violent, bowing storm complex — which downed thousands of trees and cut power to over a million people — swept from the Midwest to the Mid-Atlantic that sweltering summer night. The might of its hurricane-force winds and the disastrous aftermath remain strikingly alive.

For those who monitor, track and forecast the weather, the cache of memory instinctively reboots to bring back the sense of doom felt that evening. Meteorologists, working that day or otherwise monitoring the menacing storm complex, have kindred memories that linger for the simple reason that the event remains one of the most widespread and ruinous severe-thunderstorm entries in the diary of our region’s extreme weather.

“The 2012 derecho stands out as the fiercest D.C.-area storm that I’ve covered since joining The Washington Post in 2008,” said Jason Samenow, the Capital Weather Gang’s chief meteorologist. “It was a wild, unforgettable night.”

Derecho: Behind Washington, D.C.’s destructive thunderstorm outbreak, June 29, 2012

Before the storm complex formed, most meteorologists in the Mid-Atlantic were focused on the day’s oppressive heat and suffocating humidity. In Washington, the temperature soared to a June record of 104 degrees that day. The heat helped generate extraordinary atmospheric instability — or fuel for the storms to come.

The first hints of real trouble came in the midafternoon. As meteorologists monitored the storms that were building and bubbling eastward from the Midwest, there was growing concern that the merging line of intertwining cells would sustain strength, and even intensify, while traversing into the searing heat and sweltering humidity downwind. Indeed, the mingling of so many contributing factors ultimately resulted in a blanket of severe-thunderstorm warnings that spanned hundreds of miles by early that evening.

Meteorologists with the National Weather Service certainly took notice.

“I recall how hot it had been that day,” Larry Brown, senior meteorologist with the Weather Service in Wakefield, Va., said in an email. “It was still around 90F at 10 p.m., and I think that was a big factor that helped the storms actually intensify across the Piedmont after crossing the mountains.”

For television meteorologists, the appearance of solid blocks of severe-thunderstorm warnings to the west from late afternoon into early evening spelled certainty of significant impact east of the Appalachians. Newsrooms throughout the region were alerted by their weather teams to expect headline rewrites for the news at 11 p.m.

The fury of the derecho winds was ominously foretold by the destructive impacts as the storm bulldozed from Ohio to West Virginia.

“I remember seeing the reports of 70-plus mph gusts in West Virginia and telling our readers on social media to charge their devices and secure their lawn furniture,” Samenow said.

Sue Palka, chief meteorologist with WTTG Fox 5 in Washington, was off that night and traveling home from New York when she saw vivid lightning to the west as she approached Washington. She became “alarmed” when she saw the Weather Service’s “particularly dangerous situation” severe-thunderstorm warning on her phone.

“I urged my husband to step on it or we wouldn’t beat this line of storms home,” she said in an email. “We literally got home with only 5-10 minutes to spare! I used the time to gather flashlights and candles which my husband thought was ‘overdoing it!’ I told him we’re going to lose power when this hits.”

The “particularly dangerous situation” warning mentioned by Palka was rare for this area and added urgency to the warnings, even though there was little anyone could do to escape the damage and outages that would scour the area over just a minute or two.

“I was covering the storm from home and lost power just as it struck. I’ll never forget that sudden, jarring wall of wind,” Samenow said. “Without electricity, I was no longer able to post updates to our live blog on the storm. I called the newsroom in a panic and dictated updates to a copy editor over the phone.”

The storm complex, blasting eastward at over 60 mph, toppled so many trees that roads were impassible all over the region.

“Both my daughters were in DC that Friday night attending a theatre performance,” Palka said in her email. “So many trees and wires down that they couldn’t drive home. They briefly got word to us that they were ok before cell service was also disrupted. They finally made it home before dawn.”

“We were fortunate that our power lines are underground and power was restored in about 12 hours. Many others were to suffer for days without power in the middle of a scorching DMV summer.”

Andrew Zimmerman, a senior meteorologist at the Weather Service’s Wakefield office, remembered the smallest of silver linings.

“One thing I still recall clearly was how much the derecho modified our air mass,” he said in an email. “When I left for work the following morning it was a beautiful morning and much less humid. High temperatures the following day were greatly affected by the derecho, and we fell way short of the excessive heat warning we had out for that Saturday.”

That slight, albeit brief, expunging of the extremely hot and humid air at least gave temporary relief the following morning for the hundreds of thousands left without power and faced with assessing the damage.

But the searing heat rapidly rebuilt, and according to the post-storm assessment report from the Weather Service, there were more heat-related deaths in the days that followed than from the derecho itself. No power and no air conditioning for several days left a deadly legacy well after the 90-second torrent of winds from the derecho.

Indeed, memories on this anniversary of the 2012 derecho not only caution us about the potency of storms such as this but, just as important, tell us that for any episode of severe weather, there’s crucial need to stay aware of risks that can last long beyond the event itself.

Jim Duncan recently retired from his 40-year career as chief meteorologist with NBC12 WWBT-TV in Richmond. He runs his own meteorological consulting firm, Jim Duncan LLC, serving clients in media, education and other industries.

Read more on the 2012 derecho

Derecho of June 29, 2012: Ten telltale images of historic “land hurricane”

Dangerous chase: Derecho pursuit in Washington, D.C.

Dissecting a derecho bolt: More to lightning than meets the eye (and camera lens)

Jefferson’s derecho — the video from June 29, 2012

Could forecasters have better predicted the June 29 derecho?

Did global warming intensify the derecho in Washington, D.C.?

‘Derecho’ was one of 2012’s trending words

The forgotten derecho of 1954 that slammed Washington