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Jen Pinkowski
Jen Pinkowski

Why Are Nor'easters So Hard to Forecast?

Jen Pinkowski
Jen Pinkowski

There could be a major snowstorm along the East Coast this weekend. Of course, snowstorms are common in the United States in January. But decent thumps of wintry precipitation along the East Coast always seem to be more high-maintenance than snow in other parts of the country. These systems are notoriously hard to predict more than a day or two in advance—an uncertainty that tends to drive people crazy, especially in an era when we expect (and often get) instant answers. 

GFS model forecast from January 18, 2016, showing surface pressure (mb) and wind speed (kt) for January 23, 2016. Image credit: Pivotal Weather

If there’s one thing we humans don’t like, it’s uncertainty. Telephone psychics, fortune cookies, and novelty toys like the Magic 8-Ball thrive on our undying desire to know what the future holds. Political junkies live and breathe opinion polls to know what voters will decide before they cast their ballots. Sports analysts spend hours trying to predict the outcome of games that haven’t yet started.

But unlike the outcome of an election or sporting event, we need to know what the weather will be like in order to live and survive. Meteorologists have it harder than these forecasters because the atmosphere is unlike humans in that we have no control over what it does. We can’t directly influence a storm to move one way or another. The weather is destined to happen as it happens, and it’s a meteorologist’s seemingly impossible task to figure out what it’s going to do long before a cloud forms.

The Northeast Megalopolis has about the same population as 12 Midwestern states combined. |mage credit: Dennis Mersereau

Predicting the whereabouts and actions of a snow or ice storm on the East Coast is an especially high-stakes exercise that requires an attention to science and skill. The Interstate 95 (I-95) corridor between Richmond, Virginia, and Boston, Massachusetts, is home to more than 50 million people; this strip of land, known as the Northeast Megalopolis, is home to about as many people as 12 Midwestern states combined. New York City alone has a greater population (about 8.4 million people) than 39 of the 50 states.

Given the great amount of people who live there, many of whom are packed tightly together, snow and ice that would be seen as a simple nuisance in colder and snowier places has the potential to turn into a disaster along the I-95 corridor, crippling ground and air travel, severing power to millions, and disrupting schools and businesses for a week or more. The freak-out before a storm makes this region the butt of jokes for its reaction, but whether or not the societal chaos that unfolds is justified, a lot of this anxiety stems from uncertainty, and East Coast storms are a hard nut to crack. 

But why? All of the big, historic snows that live in the record books in cities like Washington D.C. and New York were produced by a unique kind of East Coast storm known as a “nor’easter,” so called because the storm produces strong northeasterly winds along the coast. Nor’easters form when the dynamics in the upper levels of the atmosphere come together just right to form a low-pressure system at the surface that eventually tracks off the coast of the Mid-Atlantic—think North Carolina and Virginia—and moves parallel to the coast as it heads toward New England and eventually Canada.

Nor’easters can grow into very powerful storms, sometimes the strength and size of a hurricane. The strong winds wrapping around the low-pressure system often drag bitterly cold air from the west and warm, moist air from the south. The varying temperatures through the storm usually lead to the whole spectrum of precipitation, including snow, sleet, freezing rain, and regular rain. The temperature gradient can be so sharp that two neighboring towns can see completely different weather conditions, with one hit by heavy snow while the other gets ice or rain.

When you have such dramatic differences in weather over such short distances, the track of the storm is everything when it comes to determining who will see the worst snow and who will see a cold rain—and this is usually where the greatest uncertainty lies. It takes a very specific path and combination of atmospheric ingredients in order to produce feet of snow along the I-95 corridor. It’s challenging to determine the exact track of a low-pressure system—if you’ve ever followed a hurricane drawing closer to the coast, you know that the center wobbles and shifts and can sometimes go far off the track that meteorologists predicted it would follow. Nor’easters are similar in this regard. If a storm shifts a few dozen miles to the east or west, it can result in a city that expected rain to see all snow, or a city that braced for a blizzard to wake up to clear skies.

Weather radar from January 27, 2015, showing the heaviest snow staying just east of New York City. | Source: Intellicast.com

New York City grew intimately familiar with the perils of predicting East Coast snowstorms in January 2015, when forecasters expected a powerful blizzard to bring 2 feet of snow to the Big Apple. The nor’easter tracked a few dozen miles farther out to sea than they anticipated, and most of the city ultimately got less than 10 inches of snow, while Long Island got pounded with more than 2 feet of snow.

Weather is hard. Despite the difficulty, meteorologists usually manage to predict the weather with stunning accuracy—a level of accuracy they only dreamed of just a few decades ago. We’ve gotten really good at figuring out what the weather will do in the future, but there are still some limits. Determining the exact track—down to the mile—of a large snowstorm with lots of variables pushing and pulling and swirling about is very hard. It’s doable, but in many cases it’s tough, and there’s always inherent uncertainty built into even the best forecast. When your friendly neighborhood meteorologist calls for a large range of snow totals or says that they’re not quite sure what could happen yet, just prepare for the worst and hope for the best. 

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science
The Surprising Reason Why Pen Caps Have Tiny Holes at the Top
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iStock

If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

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Big Questions
What Causes Sinkholes?
Mark Ralston/AFP/Getty Images
Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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