Meteorologists remember the mid-Atlantic derecho in June 2012

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A decade has passed since one of the most memorable storm events in Washington weather history: June 29, 2012, Derecho. The violent, bending storm complex – which downed thousands of trees and cut power to over a million people – swept from the Midwest to the Mid-Atlantic on that muggy summer night. The power of its gale force winds and the catastrophic consequences remain strikingly alive.

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

“The derecho of 2012 is the most violent DC-area storm I’ve reported on since joining the Washington Post in 2008,” said Jason Samenow, chief weather forecaster for the Capital Weather Gang. “It was a wild, unforgettable night.”

Derecho: Behind the destructive outbreak of thunderstorms in Washington, DC, June 29, 2012

Before the storm complex formed, most mid-Atlantic forecasters focused on the day’s sweltering heat and stifling humidity. In Washington, the temperature rose to a June record of 104 degrees that day. The heat helped create extraordinary atmospheric instability — or fuel for the storms to come.

The first hints of real trouble came in the afternoon. As meteorologists monitored the storms building and churning eastward from the Midwest, concern grew that the merging line of intertwined cells would maintain its strength and even intensify as it penetrated the searing heat and muggy humidity downwind . Indeed, the merging of so many factors ultimately resulted in a blanket of severe thunderstorm warnings stretching hundreds of kilometers into early evening.

Meteorologists from the National Weather Service took notice.

“I remember how hot it was that day,” Larry Brown, chief meteorologist at the Wakefield, Va., weather service, said in an email. “At 10pm it was still around 90C and I think that was a big factor in contributing to the storms actually getting stronger across Piedmont after crossing the mountains.”

For television meteorologists, the appearance of massive blocks of severe thunderstorm warnings in the west from late afternoon through early evening meant the certainty of significant impacts east of the Appalachia. Newsrooms across the region have been alerted by their weather teams to expect headline updates for the news at 11pm

The fury of the derecho winds was ominously foretold by the devastating effects as the storm rolled from Ohio into West Virginia.

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

Sue Palka, chief meteorologist at WTTG Fox 5 in Washington, was out that night, traveling home from New York, when she saw bright flashes to the west as she approached Washington. She was “shocked” when she saw the storm warning “particularly dangerous situation” from the weather service on her cell phone.

“I was urging my husband to step on it or we wouldn’t be hitting that storm line home,” she said in an email. “We literally got home with only 5-10 minutes! I used the time to collect flashlights and candles, which my husband thought was “overkill”! I told him that if this happens we will lose power.”

The “particularly dangerous situation” alert mentioned by Palka was rare for the area, increasing the urgency of the alerts, although there was little anyone could do to avoid the damage and outages that would comb the area in just a minute or two.

“I was reporting the storm from home and was losing power just as it hit. I will never forget that sudden, shattering wall of wind,” said Samenow. “Without power, I could no longer post updates on our live blog about the storm. I called the office in a panic and dictated updates to an editor over the phone.”

The storm complex, which swept east at over 60 miles per hour, downed so many trees that roads across the region were impassable.

“Both of my daughters were in DC this Friday night to see a theatrical performance,” Palka said in her email. “So many trees and cables they couldn’t drive home. They briefly let us know they were fine before the cell service was also cut off. They finally made it home before dawn.”

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

Andrew Zimmerman, chief meteorologist at the Weather Service’s Wakefield office, recalled the tiniest silver lining.

“One thing I remember vividly was how much the derecho changed our air mass,” he said in an email. “When I left for work the next morning, it was a beautiful morning and a lot less humid. High temperatures the following day were heavily influenced by the derecho and we fell well short of the excessive heat warning we issued for this Saturday.”

This slight, if brief, blow of extremely hot and humid air provided at least temporary relief the following morning for the hundreds of thousands who were without power and surveying the damage.

But the searing heat quickly built up again, and according to the Weather Service’s post-storm assessment report, there were more heat-related deaths in the days that followed than from the derecho itself -Second gale of winds from the derecho.

Indeed, memories of this anniversary of Derecho 2012 not only warn us of the strength of storms like this one, but also tell us that with any severe weather episode, it is extremely important to be aware of the risks that can linger long over the event out.

Jim Duncan recently retired from his 40-year career as Chief Meteorologist at NBC12 WWBT-TV in Richmond. He runs his own meteorological consulting company, Jim Duncan LLCserving customers in media, education and other industries.

Read more about the Derecho 2012

Derecho of June 29, 2012: Ten Tell-Tale Images of Historic “Land Hurricane”

Dangerous Chase: Derecho Chase in Washington, DC

Dissecting a Derecho Bolt: More to the Flash than the Eye (and Camera Lens)

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

Could forecasters have predicted the derecho of June 29 any better?

Has global warming amplified the derecho in Washington, DC?

“Derecho” was one of the trending words of 2012

The forgotten derecho of 1954 that slammed Washington

About Mike Crayton

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