Last night, a destructive tornado tore through a community near Charleston, S.C., destroying homes and lofting debris tens of thousands of feet into the air. Tornadoes were not in the forecast last night—this happened largely by surprise. Owning a weather radio is your best defense against unexpected natural disasters like this.

Meteorologists from the National Weather Service office in Charleston, South Carolina, are currently surveying the damage on Johns Island, a community a few miles west of the city that’s famously the home of the Angel Oak, a very old and very pretty tree that makes you feel very small when you stand next to it. Though several homes appear to have been destroyed and many more buildings were damaged, nobody was injured by the tornado (and the Angel Oak is okay).

Forecasts did not call for the chance of tornadoes last night. The Storm Prediction Center included the Charleston area under a general risk for non-severe thunderstorms, and the NWS office there did the same. However, as early as 5:30 PM on Thursday, a meteorologist did mention the risk for landfalling waterspouts in their forecast discussion:

THERE ARE SMALL PROBABILITIES FOR AN ISOLATED WATERSPOUT TO MOVE ONSHORE ALONG THE LOWER SOUTH CAROLINA COAST LATER THIS EVENING AS AN AREA OF ENHANCED LOW-LEVEL HELICITY ASSOCIATED WITH THE APPROACHING LOW AND COASTAL FRONT DRAWS CLOSER. BEST CHANCES COULD BE ALONG THE CHARLESTON COUNTY COAST.

Helicity is a parameter that tells you how conducive the winds are for a thunderstorm’s updraft to begin rotating. Some of that favorable wind shear must have moved onshore, because what happened last night was definitely not a waterspout.

(Mobile users: this GIF is 5.56 MB)

The thunderstorm that produced the tornado did have a little bit of rotation over the ocean, but the twisting cranked up after it came ashore west of Folly Beach and started making its way toward Johns Island. In the animated radar image above, you can see the hook echo for a few frames as it approaches the community.

It’s not too uncommon for a thunderstorm with rotation to drop a significant tornado once it makes landfall and encounters the friction of land. This situation is reminiscent of the EF-2 tornado that tore through Mobile, Alabama, on Christmas Day in 2012, though that occurred as part of a larger outbreak in the Deep South.

Despite the tornado occurring without anyone saying “hey, tornadoes are possible today,” the local NWS office did a very good job issuing warnings on the storm in the minutes leading up to the incident.

They issued a severe thunderstorm warning for the area at 12:37 AM, and put up a tornado warning one minute later at 12:38 AM. At 12:45 AM—seven minutes after the tornado warning went out—a sweep of the radar showed the storm kicking debris into the air.

A few minutes later—at 12:50 AM—the plume of debris was enormous, indicating that the tornado was tearing up lots trees and structures along its path. The debris signature is best seen in the product on the bottom-right (and at the top of this post), which is called the “correlation coefficient,” or CC for short. CC shows you how similar the objects are in size and shape—lower values, indicated by cooler colors, tell you there’s an area of objects of different sizes and shapes, which makes it perfect for detecting tornado debris.

The tornado sucked up so much debris during the couple of minutes it was on the ground that the radar detected items lofted as high as 15,000 to 20,000 feet into the thunderstorm.

Usually when there’s a “surprise” tornado, it wasn’t really all that unexpected. The majority of tornadoes that take people off guard are ones that either go without warning, form so quickly that there’s almost no lead time, or people simply didn’t get the warning. While some tornadoes do go unwarned—an August tornado that injured six people when it extensively damaged a Walmart in Troy, Alabama, is a recent example—the latter is probably the most common cause.

Over the years, we’ve seen countless news interviews that begin with survivors shouting the same old, tired line into the camera: “WE HAD NO WARNING!” The sad fact is that they probably did have warning, they were just in a position where they had no way of receiving that alert.

We live in an era where we’re so surrounded by technology that people go to bed with Fitbits on their wrists to track their sleeping patterns—there is absolutely no excuse for anybody not to hear a tornado warning these days.

Sometimes, though, the normal means of communication don’t do you much good. If you’re asleep, AM/FM radio and television news broadcasts are useless. Cell phone apps can be unreliable, as are those untrustworthy tornado sirens, which are only meant to be heard outdoors anyway.

This is where the benefits of a NOAA Weather Radio come into play.

I write about these devices frequently, often in advance of a dangerous severe weather outbreak, because they work. A weather radio is a smoke detector for the weather. That’s not to say that it’s the only way you can stay safe ahead of a bad storm, but it’s your best line of defense—a direct line between you and your local NWS office that, when properly set up, can alert you with a loud siren the instant they push out a severe weather alert for your county.

Tornadoes are dangerous anytime, but they’re even more so at night or when it’s the “off-season,” the months when people let their guards down and don’t expect severe weather to strike. Last night’s tornado in South Carolina fit both descriptions. The storm tore through neighborhoods after midnight, when most (if not all) of their occupants were sleeping or in a lowered state of alert, and one doesn’t typically think about tornadoes on a rainy September night, especially when they’re not called for in the forecast.

Thankfully, though numerous homes were damaged or destroyed, nobody was injured in last night’s tornado. It’ll be interesting to see if that was pure luck or if many (if not most) of the survivors received enough warning that they took adequate shelter. This incident could have easily been a tragic disaster, and one that plays out year after year in communities across the United States that are struck by tornadoes at night or with little notice.

This tornado in South Carolina is the textbook example of why everyone should own a weather radio. It’s not even just tornadoes—these devices can alert you to everything from flood warnings to evacuation orders to 911 telephone outages. It’s worth the couple of bucks, and it could save your life when you least expect it.

[Radar Images: Gibson Ridge | Radio Image: author]

Email: dennis.mersereau@gawker.com | Twitter: @wxdam

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