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 11:39 AM EDT, Thu October 30, 2014
Mike Downey says the Giants and the Royals both lived through long title droughts. What teams are waiting for a win?
updated 2:32 PM EDT, Thu October 30, 2014
Mel Robbins says if a man wants to talk to a woman on the street, he should follow 3 basic rules.
updated 5:03 PM EDT, Wed October 29, 2014
Peter Bergen and David Sterman say more terrorism plots are disrupted by families than by NSA surveillance.
updated 5:25 PM EDT, Wed October 29, 2014
Time magazine has clearly kicked up a hornet's nest with its downright insulting cover headlined "Rotten Apples," says Donna Brazile.
updated 4:55 PM EDT, Wed October 29, 2014
Leroy Chiao says the failure of the launch is painful but won't stop the trend toward commercializing space.
updated 7:45 AM EDT, Wed October 29, 2014
Timothy Stanley: Though Jeb Bush has something to offer, another Bush-Clinton race would be a step backward.
updated 8:37 AM EDT, Tue October 28, 2014
Errol Louis says forced to choose between narrow political advantage and the public good, the governors showed they are willing to take the easy way out over Ebola.
updated 2:03 PM EDT, Mon October 27, 2014
Eric Liu says with our family and friends and neighbors, each one of us must decide what kind of civilization we expect in the United States. It's our responsibility to set tone and standards, with our laws and norms
updated 7:45 AM EDT, Mon October 27, 2014
Sally Kohn says the UNC report highlights how some colleges exploit student athletes while offering little in return
updated 3:04 PM EDT, Sun October 26, 2014
Terrorists don't represent Islam, but Muslims must step up efforts to counter some of the bigotry within the world of Islam, says Fareed Zakaria
updated 9:02 AM EDT, Fri October 24, 2014
Scott Yates says extending Daylight Saving Time could save energy, reduce heart attacks and get you more sleep
updated 8:32 PM EDT, Sun October 26, 2014
Reza Aslan says the interplay between beliefs and actions is a lot more complicated than critics of Islam portray
updated 7:19 AM EDT, Mon October 27, 2014
Julian Zelizer says control of the Senate will be decided by a few close contests
updated 8:12 AM EDT, Fri October 24, 2014
The response of some U.S. institutions that should know better to Ebola has been anything but inspiring, writes Idris Ayodeji Bello.
updated 9:12 AM EDT, Tue October 21, 2014
Sigrid Fry-Revere says the National Organ Transplant Act has caused more Americans to die waiting for an organ than died in both World Wars, Korea, Vietnam, Afghanistan and Iraq
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT