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Get Your Shovel: A Big Storm Will Stun the Southeast Tonight

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Abandoned vehicles line an exit ramp along I-75 South during the winter storm January 29, 2014 in Atlanta. Drivers and kids on school buses were stuck in their vehicles overnight. Image Credit: Daniel Shirey/Getty Images

 
A significant winter storm will stun parts of the southeastern United States overnight on Friday, January 6, greeting the first full weekend of the new year with a crust of snow from the fields of Alabama to the beaches of Virginia. The storm could produce amounts of snow this region only sees once or twice a decade, potentially snarling traffic and leading to widespread business closings. And as if the snow isn’t bad enough, a bitter cold snap will follow soon after and make post-storm cleanup even more challenging.

The snow and ice will start on Friday afternoon as a low-pressure system comes together at the surface due to a strong jet stream streaking overhead from west to east. Winds swirling around the low will help drag Arctic air as far south as the Gulf of Mexico, ensuring that most of the precipitation that falls across the south on Friday and Saturday falls in the form of snow, sleet, or freezing rain.

Folks in Alabama and Georgia can expect the wintry precipitation to begin before sundown on Friday and last through the nighttime hours. The heaviest snow and ice will reach the Carolinas and Virginia after sunset on Friday and last through Saturday morning, ending from west to east as the storm trudges out to sea.

The Weather Prediction Center’s snowfall forecast from the morning of January 6, 2017, through the morning of January 9. Image Credit: Dennis Mersereau

 
Meteorologists expect this storm to be a nuisance in Alabama and Georgia and a genuine thumping as you head farther north along the coast. Central Alabama can expect a general dusting of snow with localized higher amounts, while a couple of inches of snow are likely across adjacent parts of Georgia. Atlanta is understandably jittery about even a small blanket of the white stuff given how frozen precipitation has paralyzed the city in recent years. Small amounts of snow can readily freeze into a sheet of ice on heavily trafficked roads, bringing vehicles to a standstill and stranding commuters for many hours before help arrives.

The heaviest snow is expected to fall along a stretch of land that extends from about Charlotte, North Carolina, through Norfolk, Virginia. This is where forecasters expect the greatest mixture of cold air, deep moisture, and upward lift to generate hours of steady—and at times heavy—snowfall. Close to 6 inches of snow are possible in many of these locations, with some totals closer to 1 foot possible between Raleigh, North Carolina, and the Virginia beaches.

A sloppy mixture of snow, ice, and plain old rain is possible closer to the coast where temperatures will be warmer. A thin glaze of ice is possible from central Alabama through eastern parts of the Carolinas by the end of the storm. Even though ice accretions are expected to measure just a few hundredths of an inch, any coating of ice will make roads and sidewalks slick and potentially impassable.

The National Weather Service’s forecast low temperatures, in degrees Fahrenheit, for the morning of Monday, January 9, 2016. Image Credit: NWS EDD

 
The hazards don’t end with the snow. Temperatures for several days after the skies clear out will be brutally cold compared to normal, approaching record territory in some spots. Low temperatures on Sunday night will likely reach the single digits as far south as Charlotte, North Carolina, with some communities pushing zero degrees before sunrise. Temperatures will likely remain below freezing from Friday night until Tuesday afternoon across areas where the thickest blanket of snow falls, complicating cleanup efforts and making rush hour on Monday and Tuesday a dicey bet. Snow that isn’t removed from roads and sidewalks soon after it falls risks freezing into thick layers of solid ice as the sun melts it and subfreezing temperatures refreeze the meltwater.

The South’s inability to cope with even the tiniest snowfall is a running joke in the rest of the country, but this typically mild region just isn’t equipped to deal with significant amounts of winter weather. Many factors play into this unique problem, including inadequate infrastructure and the simple fact that people just aren’t used to winter driving. The saving grace with this storm should be that the bulk of the hazardous weather will occur overnight on a weekend, minimizing traffic congestion and disruption to everyday life.

This storm has been well-advertised since the beginning of this week, and stores started running out of bread and milk as soon as Wednesday afternoon. People certainly know it’s coming. Still, this storm could cause unexpected disruptions where the forecast doesn’t hit the mark. Exact snow and ice accumulations depend on the track that this storm takes. A tiny shift to the north or south in the storm’s track could result in the bands of heaviest snow setting up farther north or south of where forecasters and models think it’ll set up right now. A track error of just 25 miles could mean that towns expecting a light snowfall could get slammed while cities expecting to spend an afternoon shoveling might get lucky and not see much at all. As with everything in life, prepare for the worst but hope for the best.

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Weather Watch
3 Ways We Can (Kind of) Control the Weather, and 5 Ways We Can't

Humans have the incredible ability to control the world around us. We can move mountains and land robots on other planets. We can keep each other alive longer than ever before and even bring entire species back from the brink of extinction. But despite all of our leaps forward, we're still unable to control the weather, a tremendous force that affects every human being on this planet. Still, humans have come up with some pretty crafty ways of influencing the weather—in small doses.

1. WE CAN MAKE IT RAIN … SOMEWHAT.

The desire to control weather has been a mainstay of imagination since, well, the beginning of imagination. The fortunes of entire societies can hinge on flood or drought. We have strong motivation to want to create a rainstorm in one spot or moderate snowfall in another. But the greatest success we've ever had is a technique that can (maybe) encourage a tiny bit of rain to form over a tiny area.

Cloud seeding is a process through which fine particles like silver iodide are released into a cloud in order to encourage the formation of rain or snow. These particulates serve as a nucleus around which water vapor can condense and turn into a raindrop or a snowflake. This is most commonly done with small airplanes, but it can also be accomplished by launching tiny rockets or flares from the ground.

In theory, the practice of cloud seeding could have innumerable uses around the world, including crop maintenance, providing drinking water, and even possibly weakening severe thunderstorms or hurricanes. There's only one problem: It doesn't work all that well.

The effectiveness of cloud seeding is a hot topic of debate among scientists, but most studies have either found negligible impacts on precipitation, or the researchers were unable to determine the exact impact of cloud seeding. Cloud seeding is a great concept if you want to help one cloud produce a little extra rain or snow just to say you can do it, but it's not the way to go if you're desperate and want to trigger a deluge. This process requires the pre-existing presence of clouds, so even if the technology improves in the future, it's not a viable solution for drought-stricken areas that haven't seen meaningful clouds in weeks.

2. WE CAN DEFINITELY ATTRACT LIGHTNING USING ROCKETS.

Lightning safety is one of the things you learn from a very young age. "When thunder roars, go indoors," as the motto goes. We learn to stay away from open areas and water during thunderstorms. But what if you wanted to attract lightning? It's surprisingly easy to do if you have the right equipment and really, really want to encounter some of nature's fury.

Scientists who want to study lightning can bring it right to their doorstep by using specially designed rockets attached to conductive wires that lead to the ground below. When a thunderstorm blows over the observation station, operators can launch these rockets up into the clouds to trigger a lightning strike that follows the wire right down to the ground where the rocket was launched. Voila, instant lightning. Just add rocket fuel.

3. WE CAN CREATE CLOUDS AND HEAT—EVEN WHEN WE DON'T MEAN TO.

Most of the ways in which we control—or, more accurately, influence—the weather is through indirect human actions—often unintentional. "Whoops, the nuclear power plant just caused a snowstorm" isn't as crazy as it sounds. Steam stacks can and do produce clouds and updrafts with enough intensity to create rain or snow immediately downwind. The very presence of cities can generate microclimates with warmer temperatures and heavier rain. And there's also climate change, the process in which our accumulated actions over a long period of time are influencing the very climate itself.

BUT WE CAN'T DO THE FIVE FOLLOWING THINGS.

Despite our limited ability to influence a few aspects of weather over small areas, there are some rather colorful conspiracy theories about whether or not governments and organizations are telling the whole truth about how much we can accomplish with today's technology. There are folks who insist that the trails of condensed water vapor, or "contrails," left behind jet aircraft are really chemicals being sprayed for sinister purposes. (They're not.) There are theories that a high-frequency, high-power array of antennas deep in the Alaskan wilderness can control every weather disaster in the world. (It doesn't.) There are even folks who insist that Doppler weather radar carries enough energy to "zap" storms into existence on demand. (Dr. Evil wishes.)

There are also some bizarre and unworkable theories that are offered in good faith. A meteorologist a few years ago opined on whether building an excessively tall wall across middle America could disrupt weather patterns that could lead to tornado activity. And every year the National Hurricane Center is peppered with questions about whether or not detonating nuclear bombs in a hurricane would disrupt the storm's structure. Unfortunately, while pseudoscience offers up great theories to test in the movies, when it comes to weather, we're still not in control.

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Weather Watch
NASA Figures Out Why When It Rains, It (Sometimes) Drizzles
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What’s the difference between drizzle and rain? It has to do with updrafts, according to new research by NASA scientists into the previously unexplained phenomenon of why drizzle occurs where it does.

The answer, published in the Quarterly Journal of the Royal Meteorological Society, could help improve how weather and climate models treat rainfall, making predictions more accurate.

Previously, climate researchers thought that drizzle could be explained by the presence of aerosols in the atmosphere. The microscopic particles are present in greater quantities over land than over the ocean, and by that logic, there should be more drizzle over land than over the ocean. But that's not the case, as Hanii Takahashi and her colleagues at the Jet Propulsion Laboratory found. Instead, whether or not rain becomes full droplets or stays as a fine drizzle depends on updrafts—a warm current of air that rises from the ground.

Stronger updrafts keep drizzle droplets (which are four times smaller than a raindrop) floating inside a cloud longer, allowing them to grow into full-sized rain drops that fall to the ground in the splatters we all know and love. In weaker updrafts, though, the precipitation falls before the drops form, as that light drizzle. That explains why it drizzles more over the ocean than over land—because updrafts are weaker over the ocean. A low-lying cloud over the ocean is more likely to produce drizzle than a low-lying cloud over land, which will probably produce rain.

This could have an impact on climate modeling as well as short-term weather forecasts. Current models make it difficult to model future surface temperatures of the Earth while still maintaining accurate projections about the amount of precipitation. Right now, most models that project realistic surface temperatures predict an unrealistic amount of drizzle in the future, according to a NASA statement. This finding could bring those predictions back down to a more realistic level.

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