Skip to main content

Can you trust the weatherman?

By Julie Crockett, Special to CNN
February 9, 2013 -- Updated 1846 GMT (0246 HKT)
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
October 28, 2014 -- Updated 1237 GMT (2037 HKT)
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.
October 27, 2014 -- Updated 1803 GMT (0203 HKT)
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
October 27, 2014 -- Updated 1145 GMT (1945 HKT)
Sally Kohn says the UNC report highlights how some colleges exploit student athletes while offering little in return
October 26, 2014 -- Updated 1904 GMT (0304 HKT)
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
October 24, 2014 -- Updated 1302 GMT (2102 HKT)
Scott Yates says extending Daylight Saving Time could save energy, reduce heart attacks and get you more sleep
October 27, 2014 -- Updated 0032 GMT (0832 HKT)
Reza Aslan says the interplay between beliefs and actions is a lot more complicated than critics of Islam portray
October 27, 2014 -- Updated 1119 GMT (1919 HKT)
Julian Zelizer says control of the Senate will be decided by a few close contests
October 24, 2014 -- Updated 1212 GMT (2012 HKT)
The response of some U.S. institutions that should know better to Ebola has been anything but inspiring, writes Idris Ayodeji Bello.
October 22, 2014 -- Updated 2101 GMT (0501 HKT)
Paul Callan says the grand jury is the right process to use to decide if charges should be brought against the police officer
October 23, 2014 -- Updated 1619 GMT (0019 HKT)
Theresa Brown says the Ebola crisis brought nurses into the national conversation on health care. They need to stay there.
October 21, 2014 -- Updated 2235 GMT (0635 HKT)
Patrick Hornbeck says don't buy the hype: The arguments the Vatican used in its interim report would have virtually guaranteed that same-sex couples remained second class citizens
October 24, 2014 -- Updated 1630 GMT (0030 HKT)
The Swedes will find sitting on the fence to be increasingly uncomfortable with Putin as next door neighbor, writes Gary Schmitt
October 24, 2014 -- Updated 1632 GMT (0032 HKT)
The Ottawa shooting pre-empted Malala's appearances in Canada, but her message to young people needs to be spread, writes Frida Ghitis
October 26, 2014 -- Updated 0148 GMT (0948 HKT)
Paul Begala says Iowa's U.S. Senate candidate, Joni Ernst, told NRA she has right to use gun to defend herself--even from the government. But shooting at officials is not what the Founders had in mind
October 23, 2014 -- Updated 2208 GMT (0608 HKT)
John Sutter: Why are we so surprised the head of a major international corporation learned another language?
October 23, 2014 -- Updated 2154 GMT (0554 HKT)
Jason Johnson says Ferguson isn't a downtrodden community rising up against the white oppressor, but it is looking for justice
October 24, 2014 -- Updated 1621 GMT (0021 HKT)
Sally Kohn says a video of little girls dressed as princesses using the F-word very loudly to condemn sexism is provocative. But is it exploitative?
October 21, 2014 -- Updated 2006 GMT (0406 HKT)
Timothy Stanley says Lewinsky is shamelessly playing the victim in her affair with Bill Clinton, humiliating Hillary Clinton again and aiding her critics
October 23, 2014 -- Updated 1414 GMT (2214 HKT)
Imagine being rescued from modern slavery, only to be charged with a crime, writes John Sutter
October 21, 2014 -- Updated 1600 GMT (0000 HKT)
Tidal flooding used to be a relatively rare occurrence along the East Coast. Not anymore, write Melanie Fitzpatrick and Erika Spanger-Siegfried.
October 21, 2014 -- Updated 1135 GMT (1935 HKT)
Carol Costello says activists, writers, politicians have begun discussing their abortions. But will that new approach make a difference on an old battleground?
October 21, 2014 -- Updated 1312 GMT (2112 HKT)
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