Sean McCullough, left, plays with his children in Copley Square in Boston on Sunday, February 10, following a powerful blizzard. The storm dumped more than two feet of snow in parts of New England.
Editor's note: Julie Crockett is an assistant professor of mechanical engineering at Brigham Young University.
(CNN) -- A powerful storm is making its way through the northeastern U.S., expected to dump 2 feet of snow or more in some areas.
This weekend will be another test of how accurate those forecasts are.
Weather forecasts are much more accurate today than decades ago, but they are still not perfect. There are two big hurdles to overcome. One is creating accurate mathematical descriptions of the dynamics of the atmosphere. Two is increasing the resolution of the weather model.
There are many features of the atmosphere that interact in complex ways. For example, the microphysics of clouds is very hard to describe mathematically, and varies for different types of clouds. There are internal gravity waves, which propagate continuously through the atmosphere with significant energy and have the capability of driving, or slowing, strong winds.
The atmosphere includes general circulations that are affected by each other, and by the dynamics of the ocean and rotation of the earth. Depending on the temperature, pressure and humidity of the air, clouds will form and eventually result in rain. Any anomaly can change the entire system. (Just think of the Butterfly Effect, in which a small change such as a butterfly flapping its wings can affect something bigger, like a bird flying by, which can affect something even bigger, like an airplane, until a storm is formed.) Once we find that anomaly, we can track it because we know how the surrounding circulations can affect it.
By the numbers: Northeast blizzard
We predict the weather by putting all the observations we have on winds, temperatures, pressures and other variables into a mathematical model that estimates how these systems will interact. Unfortunately, the earth's circumference at the equator is almost 25,000 miles, so when we try to model the entire earth, and go up into the mesosphere (about 25 to 50 miles above the earth) the picture gets fuzzier.
Meteorologists can tell you, about five days out, with fair certainty what the weather will be like in your city or town. But it's nearly impossible to accurately model strong weather systems such as big storms or hurricanes, which include various cloud systems.
In 2011, some residents in Staten Island, New York, evacuated from their homes before Hurricane Irene approached, but Irene took another path and the evacuation turned out to be unnecessary. The mathematical model wasn't wrong, but it couldn't know with absolute certainty the pathway of Irene.
In 2010, a big winter storm was predicted for Utah. Many schools in the state canceled classes. The storm turned out not to be not so bad. This may be partly due to the effect of small, unresolved variations in the atmosphere, such as internal waves, that weakened the storm.
Staying safe when the lights go out
Although miscalculations occur, they are not particularly common, especially over the past decade. We have a much better understanding of the dynamics of the atmosphere, more observations from towers, balloons and radar, and faster computers with much more processing speed and memory. Weather forecasting models are continually improving.
Meteorologists are expected to know everything that is happening around the earth and tens of miles into the atmosphere. That's more space than we can even fathom. And all of the systems within that space affect each other.
Think of it this way: A meteorologist's job is equivalent to guessing when a flashmob is going to break out. At the outset, it seems impossible. But if you meet every person in your city, get to know each of their general habits, and keep track of everyone's plans, you could guess when they might break out into song and dance as a group.
We now know more about all of the systems in the atmosphere, how they affect each other and how they interact. There can still be anomalies, like that out-of-towner, but overall we have a pretty good idea what is going to happen and when. And if an anomaly occurs, how it will affect the entire system.
We tease meteorologists about being wrong when they can't predict the weather to the exact detail, but their job is much harder than most people understand. Just try to remember that the next time you have to shovel yourself out of that unexpected extra 6 inches of snow.
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The opinions expressed in this commentary are solely those of Julie Crockett.
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A man walks by a storefront behind large snowdrifts on Boylston Street in Boston on February 10.
A woman walks past a man clearing snow from a sidewalk on February 10 in Boston.
A man walks past snow banks in the Back Bay neighborhood on February 10 in Boston.
Snowmen made from backstage lamps, paper rolls and water bottle caps stand outside the rest area during Fashion Week in New York on February 10.
Snow blankets Copley Square on Saturday, February 9, in Boston.
People walk and sled through a snowy Prospect Park in Brooklyn, New York, on Saturday.
People attempt to push a stuck vehicle in the Back Bay neighborhood of Boston on Saturday.
A boy pulls a sled through a snowy Prospect Park in Brooklyn on Saturday.
A boy snowboards in Boston Common on Saturday.
People play in the snow in New York's Central Park on Saturday.
A young woman jumps down from snow piled in front of the Massachusetts State House after posing for a photo in Boston on Saturday.
A man walks along a snow-covered trail in Central Park on Saturday.
A child tubes down snow-covered stairs in Central Park on Saturday.
Emmet's on Beacon Street is covered in snow in Boston on Saturday.
A front loader and truck drive down Warren Street in the Brighton neighborhood on Saturday in Boston.
People walk along the Brooklyn Bridge following a major winter storm on Saturday in New York City. Possible record-setting blizzard conditions are expected with heavy snow warnings in effect from New Jersey through southern Maine.
The sculpture "Double Check" by John Seward Johnson II is seen in Zuccotti Park following a major winter storm on Saturday in New York City on Saturday.
People walk along a street devoid of snow due to ocean flooding Saturday in Winthrop, Massachusetts. Coastal flooding is expected as the storm lingers into the day.
A person walks through the snow in an alley in Hoboken, New Jersey, on Saturday.
Children carry a sled through the Financial District in New York City on Saturday.
Saniyyah Phillips, 8, scrapes the snow off of the top of her father's car in the Brighton neighborhood of Boston on Friday.
Snow covers a sidewalk and building awning in Boston on Saturday.
Josephine Sipayung and her son Eric, 6, sled down an empty street past snow-covered vehicles in Boston on Saturday.
Snow-covered vehicles sit on Commonwealth Avenue in the Brighton neighborhood of Boston on Saturday.
A worker carries a snow shovel across the Ground Zero construction sight on Saturday in New York.
A woman walks through the snow as a worker clears snow from a sidewalk in the Back Bay neighborhood of Boston.
Snow gathers on shoes hung from power lines in the Lower East Side of New York City.
Mary Leahy shovels her sidewalk in Medford, Massachusetts.
Paul DeCarlo uses a snow blower to clear the walk in front of his house in Greenfield, Massachusetts.
A man walks through snowy Central Park in New York.
Mike Streeter shovels snow in his front yard as ocean water crashes over the sea wall just feet away on February 9 in Winthrop, Massachusetts.
A pair of cows feed in the snow at Eden Pond Farm in Leyden, Massachusetts.
A child drags his toboggan up a hill in Central Park.
A woman walks in Boston on Saturday.
Phoebe Lightburn, 9, makes a snow angel in Central Park in New York.
A man shovels snow along Winthrop Shore Drive in Winthrop, Massachusetts.
A cyclist rides through the snow in the Back Bay neighborhood of Boston.
Snow blankets Boston on February 9.
Pedestrians shield themselves from blowing snow as a blizzard arrives in the Back Bay neighborhood of Boston on Friday, February 8.
Two women look for a taxi in snow-covered Times Square on February 8.
A food vendor stands under his cart as snow falls in Times Square.
A man shovels snow in front of the Apple store in New York on February 8.
People wait for a taxi in the snow in Times Square.
A pedestrian makes his way through driving snow with a broken umbrella in the Back Bay neighborhood on Friday, February 8 in Boston.
A fashion week attendee makes her way through the snow in high-heeled shoes on Friday.
Snow is cleared in front of Boston Public Library on Friday.
New York City residents cross a street covered in slush on Friday during a storm affecting the Northeast on Friday.
A woman walks through the snow past Copley Square on Friday in Boston. Massachusetts and other states from New York to Maine are preparing for a major blizzard with possible record amounts of snowfall in some areas.
A snowplow sits on the street while snow falls near Boston Common on Friday.
People walk through Times Square as a major winter storm moves in on Friday.
A snowman sits on the duck pond in the Boston Common.
A woman hails a taxi as snow and freezing rain fall over Midtown Manhattan as the city braced for the major storm on Friday.
A man operates a snow blower in the Back Bay neighborhood on Friday in Boston.
Memorial Drive sits empty following a driving ban and state of emergency that was issued in Boston on Friday.
Pedestrians battle wind, snow and sleet in Manhattan on Friday.
People walk through the snow in Boston's Back Bay neighborhood on Friday.
Bicyclists wait at a light in wind, snow and sleet on Friday.
This umbrella doesn't stand a chance in the wind-driven snow Friday in Boston as a potentially 
Jeannine Strampel walks through the snow past a statue of Alexander Hamilton along Commonwealth Avenue Mall on February 8.
Jerry Trebino loads sand onto the back of a snowplow February 8 in Wrentham, Massachusetts. The storm is expected to spawn travel headaches for a large swath of the region.
A woman battles her way to the subway in Boston on February 8.
Skiing seems like a good idea as snow begins to fall in Boston on February 8.
A woman struggles with her umbrella in New York's Financial District on February 8. Accumulations of up to a foot of snow are expected in the Big Apple.
Ines Cuadrado, left, and Anne Levine trek along a snow-covered road in Middlefield, Connecticut, on February 8.
Alfie Times shovels snow from the sidewalk outside the XL Center in Hartford, Connecticut, on February 8.
Ricky Varona copes with the wind and precipitation February 8 in New York.
Tourists brave the high winds in New York's Financial District on February 8.
A sweeper clears snow in front of the Mercedes-Benz Fashion Week tents on February 8 at Lincoln Center in New York.
A man walks along the promenade in Brooklyn Heights as Lower Manhattan stands in a cloud of snow and sleet in the early hours of a major winter storm on February 8.
A man walks across the Brooklyn Bridge in the snow and sleet on February 8.
Cars are lined up outside a gas station in Queens borough of New York on February 8.
A sign bears bad news on a fuel pump in Manhasset, New York, on February 8.
A woman tries to shield herself from wind and precipitation as the beginnings of a large winter storm hits the New York area on February 8.
Snow falls over Lower Manhattan in the early hours of a major winter storm on February 8.
A woman tries to right her umbrella while dealing with wind and precipitation in New York on February 8.
Two people carefully walk across the Brooklyn Bridge in the snow and sleet on February 8.
A satellite image released by the National Oceanic & Atmospheric Administration on February 8, shows a large storm over the Northeastern United States.
People walk through the blowing snow while a blizzard arrives in the Back Bay neighborhood on February 8 in Boston.
A man operates a snowblower while a blizzard arrives in the Back Bay neighborhood in Boston on February 8.
A sign warns drivers along Interstate 495 of a blizzard watch in Franklin, Massachusetts, on Thursday, February 7.
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