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Weather Service is adding ‘destructive’ to its storm-warning language. Your smartphone will notice.

The National Weather Service is turning up the volume on some of its thunderstorm alarms.

A strong line of storms moves toward Center City seen from Brewerytown in June 2020. The National Weather Service will add the "destructive" label to extreme thunderstorms.
A strong line of storms moves toward Center City seen from Brewerytown in June 2020. The National Weather Service will add the "destructive" label to extreme thunderstorms.Read moreMONICA HERNDON / Staff Photographer

Emergency managers and the people they are paid to protect were warned that nature was about to deliver something disruptive, yet the ferocity of what followed that steamy night in 2012 was shocking.

The traditional “severe thunderstorm” warnings were issued, but they could not capture what occurred late on June 29 and early on June 30, when a powerful derecho — a rapidly moving and propagating squall line — knocked out power to four million customers from Ohio to the Atlantic coast. Winds gusted perhaps to 100 mph at the Jersey Shore.

It wouldn’t be the last time that the warning language didn’t quite cut it: “Severe thunderstorm” doesn’t have the same attention-getting power as, say, “tornado.” So now the National Weather Service is about to raise the volume on some of those thunderstorm alarms.

» READ MORE: ‘Derecho,’ calm, and supercell thunderstorms a 'rare’ and deadly combination for Philly region

Starting later this month it will add the “destructive” tag to warnings on the potentially most damaging thunderstorms, such as the derecho encore that ripped through here in June 2020.

Thursday’s storms took down tree limbs and wires, and did prompt one “tornado warning” and a possible sighting in Milford, Del., but the thunderstorms themselves would not have qualified for the “destructive” tag.

It will be coded in such a way as to automatically activate a wireless emergency alert, which means your smartphone will get the shakes and begin making scary noises, as it does for certain other emergencies. It will show up as a text message, followed by what FEMA describes as “a unique attention signal and vibration, which is particularly helpful to people with hearing or vision-related disabilities.”

The weather service also will add a “considerable” damage label that won’t set off the alarms but will be a step above the generic “base” category, which will have descriptions of expected winds and hail size, said Sarah Johnson, lead meteorologist at the agency’s office in Mount Holly.

The warnings won’t be bound by county or state boundaries, she said, but rather by “polygons” — think rectangles and their variants — that can be smaller than a county or as large as a state, depending on the threat.

The phone alerts will be tied to where you are, not where you live, she said. So if you’re away on vacation enjoying a cocktail at sunset, you wouldn’t get an alarm alerting you that you might have to file a significant insurance claim when you get back home.

Montgomery County officials are bullish on the automatic alert, said spokesperson Todd Stieritz. “We believe that these changes will be beneficial,” he said.

Those changes did not come lightly, or quickly.

The process

After the devastating 2011 tornado season, the weather service added voltage to its twister warnings by invoking the word catastrophic in some of its tornado bulletins, said Jasmine Blackwell, spokesperson for the National Oceanic and Atmospheric Administration.

A year later came the derecho.

In its post-derecho assessment, the weather service said: “A common theme that emerged from talking to emergency managers, media, and the public was that although they received the warnings, they were surprised by the intensity of the winds.”

» READ MORE: More than 45 deaths, 4 million power outages, part of legacy of 'derecho'

Blackwell said that in the years since, “there have been plenty of instances where either high-end wind events or destructive hail storms have hit different parts of the country,” and it was the same deal. “Many people affected did not feel that they had adequate lead time to prepare, despite warnings being issued well in advance.”

Four years ago, she said, the weather service began working on the thunderstorm language upgrades, drawing on social science research, and “an extensive internal and external feedback gathering effort.”

Destructive won the day.

“Many, many news articles, survivor accounts, and general descriptions of these past wind and/or hailstorms used that term,” she said.

» READ MORE: Most warnings are false alarms, but tornado watches get attention — with good reason