Skip to main content

Can you trust the weatherman?

By Julie Crockett, Special to CNN
updated 1:46 PM EST, Sat February 9, 2013
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. 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.
HIDE CAPTION
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
Northeast blizzard
`Northeast blizzard
Northeast blizzard
<<
<
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
>
>>
STORY HIGHLIGHTS
  • A powerful storm is making its way through the Northeast
  • Julie Crockett: Weather forecasts are much more accurate than decades ago
  • It's nearly impossible to accurately model strong weather systems, she says
  • Crockett: The dynamics of the atmosphere is complex; meteorologists have a tough job

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.

Julie Crockett
Julie Crockett

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

Become a fan of CNNOpinion
Stay up to date on the latest opinion, analysis and conversations through social media. Join us at Facebook/CNNOpinion and follow us @CNNOpinion on Twitter. We welcome your ideas and comments.



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.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of Julie Crockett.

ADVERTISEMENT
Part of complete coverage on
updated 12:26 PM EDT, Wed August 27, 2014
The death of Douglas McAuthur McCain, the first American killed fighting for ISIS, highlights the pull of Syria's war for Western jihadists, writes Peter Bergen.
updated 6:42 PM EDT, Tue August 26, 2014
Former ambassador to Syria Robert Ford says the West should be helping moderates in the Syrian armed opposition end the al-Assad regime and form a government to focus on driving ISIS out
updated 9:21 AM EDT, Wed August 27, 2014
Ruben Navarrette says a great country does not deport thousands of vulnerable, unaccompanied minors who fled in fear for their lives
updated 9:19 AM EDT, Wed August 27, 2014
Robert McIntyre says Congress is the culprit for letting Burger King pay lower taxes after merging with Tim Hortons.
updated 7:35 PM EDT, Tue August 26, 2014
Wesley Clark says the U.S. can offer support to its Islamic friends in the region most threatened by ISIS, but it can't fight their war
updated 7:26 AM EDT, Wed August 27, 2014
Jeff Yang says the tech sector's diversity numbers are embarrassing and the big players need to do more.
updated 4:53 PM EDT, Tue August 26, 2014
America's painful struggle with racism has often brought great satisfaction to the country's rivals, critics, and foes. The killing of Michael Brown and its tumultuous aftermath has been a bonanza.
updated 4:19 PM EDT, Tue August 26, 2014
Ed Bark says in this Emmy year, broadcasters CBS, ABC and PBS can all say they matched or exceeded HBO. These days that's no small feat
updated 3:19 PM EDT, Tue August 26, 2014
Rick Martin says the death of Robin Williams brought back memories of his own battle facing down depression as a young man
updated 11:58 AM EDT, Tue August 26, 2014
David Perry asks: What's the best way for police officers to handle people with psychiatric disabilities?
updated 3:50 PM EDT, Mon August 25, 2014
Julian Zelizer says it's not crazy to think Mitt Romney would be able to end up at the top of the GOP ticket in 2016
updated 4:52 PM EDT, Mon August 25, 2014
Roxanne Jones and her girlfriends would cheer from the sidelines for the boys playing Little League. But they really wanted to play. Now Mo'ne Davis shows the world that girls really can throw.
updated 12:29 PM EDT, Mon August 25, 2014
Peter Bergen and Emily Schneider say a YouTube video apparently posted by ISIS seems to show that the group has a surveillance drone, highlighting a new reality: Terrorist groups have technology once only used by states
updated 5:04 PM EDT, Mon August 25, 2014
Kimberly Norwood is a black mom who lives in an affluent neighborhood not far from Ferguson, but she has the same fears for her children as people in that troubled town do
updated 5:45 PM EDT, Fri August 22, 2014
It apparently has worked for France, say Peter Bergen and Emily Schneider, but carries uncomfortable risks. When it comes to kidnappings, nations face grim options.
updated 1:27 PM EDT, Tue August 26, 2014
John Bare says the Ice Bucket Challenge signals a new kind of activism and peer-to-peer fund-raising.
updated 8:31 AM EDT, Fri August 22, 2014
James Dawes says calling ISIS evil over and over again could very well make it harder to stop them.
updated 9:05 PM EDT, Sat August 23, 2014
As the inquiry into the shooting of Michael Brown continues, critics question the prosecutor's impartiality.
updated 6:47 PM EDT, Fri August 22, 2014
Newt Gingrich says it's troubling that a vicious group like ISIS can recruit so many young men from Britain.
updated 10:50 AM EDT, Thu August 21, 2014
David Weinberger says Twitter and other social networks have been vested with a responsibility, and a trust, they did not ask for.
updated 7:03 AM EDT, Fri August 22, 2014
John Inazu says the slogan "We are Ferguson" is meant to express empathy and solidarity. It's not true: Not all of us live in those circumstances. But we all made them.
updated 8:23 AM EDT, Fri August 22, 2014
Retired Lt. Gen. Mark Hertling says he learned that the territory ISIS wants to control is amazingly complex.
updated 3:51 PM EDT, Wed August 20, 2014
Cerue Garlo says Liberia is desperate for help amid a Ebola outbreak that has touched every aspect of life.
updated 1:42 PM EDT, Thu August 21, 2014
Eric Liu says Republicans who want to restrict voting may win now, but the party will suffer in the long term.
updated 11:38 AM EDT, Thu August 21, 2014
Jay Parini: Jesus, Pope and now researchers agree: Wealth decreases our ability to sympathize with the poor.
updated 8:00 AM EDT, Thu August 21, 2014
Judy Melinek offers a medical examiner's perspective on what happens when police kill people like Michael Brown.
updated 6:03 PM EDT, Tue August 19, 2014
It used to be billy clubs, fire hoses and snarling German shepherds. Now it's armored personnel carriers and flash-bang grenades, writes Kara Dansky.
updated 1:27 PM EDT, Wed August 20, 2014
Maria Haberfeld: People who are unfamiliar with police work can reasonably ask, why was an unarmed man shot so many times, and why was deadly force used at all?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT