Skip to main content

Why is Sandy unusual?

By David Nolan, Special to CNN
updated 10:46 PM EDT, Mon October 29, 2012
Atlantic City, New Jersey, resident Kim Johnson inspects the area around her apartment building, which flooded on Tuesday, October 30. Large sections of an old boardwalk also were destroyed by Superstorm Sandy. Nearly 11,000 people spent Monday night in 258 Red Cross-operated shelters across 16 states because of Sandy, the American Red Cross tells CNN.<strong> </strong><strong><a href='http://www.cnn.com/2012/10/30/us/gallery/ny-sandy/index.html'>View photos of New York recovering from impact</a></strong><strong>.</strong> Atlantic City, New Jersey, resident Kim Johnson inspects the area around her apartment building, which flooded on Tuesday, October 30. Large sections of an old boardwalk also were destroyed by Superstorm Sandy. Nearly 11,000 people spent Monday night in 258 Red Cross-operated shelters across 16 states because of Sandy, the American Red Cross tells CNN. View photos of New York recovering from impact.
HIDE CAPTION
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
Sandy's destructive path
<<
<
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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
>
>>
STORY HIGHLIGHTS
  • David Nolan: As far as hurricanes go, the storm we call "Sandy" is not very intense
  • Nolan: There are two elements that make Sandy unusual, possibly even "super"
  • He says Sandy's right-to-left pathway is atypical, as is its intact hurricane core
  • Nolan: Sandy will take its place in history, but we'll have to wait until it's over to know where

Editor's note: David Nolan is associate professor of meteorology and physical oceanography at the Rosenstiel School of Marine and Atmospheric Science, University of Miami.

(CNN) -- As far as hurricanes go, Sandy is not particularly intense. With peak winds at 90 mph Monday at 5 p.m., it is still classified as a Category One, with only a small chance of briefly achieving the low end of Category Two before making landfall somewhere in New Jersey on Monday evening.

And yet, state and local governments have gone into full alert mode, with schools closed, cities shut down, and evacuations ordered across the Eastern Seaboard. Justifying the alarm are enormous waves arriving onshore, raising the mean water level by a few feet even here in Miami, where the winds are blowing directly offshore.

Sandy could bring 'catastrophe,' affect 60 million

Sandy represents the confluence of a modestly strong hurricane coming up from the Caribbean and a fairly strong but not unusual continental weather system -- what meteorologists call a "trough" or "dip" in the jet stream -- that has been traversing the country over the last few days.

David Nolan
David Nolan

In the vast majority of cases, these weather systems weaken hurricanes while at the same time pushing them quickly out to sea. Such weather systems also generate their own cyclones, not as intense as hurricanes, but larger and slower moving.

Opinion: As Sandy descends, tips from Katrina survivors

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.



When these extra-tropical cyclones form over the ocean and move along the coast, we call them nor'easters (for the strong northeasterly winds they generate). Sometimes, tropical and extra-tropical systems merge, and the hurricane turns into a large ocean cyclone. But again, almost all of these storms move quickly out to sea.

There are two elements that make Sandy very unusual, possibly even "super."

First is its pathway. Rather than racing out to sea like most coastal storms, Sandy has already turned hard to the left and it will make landfall at nearly a right angle to the U.S. coastline. This extremely unusual track (from right to left) means that almost every piece of coastline from New Jersey to Cape Cod will receive onshore winds at some point during the event.

ISS flies over Hurricane Sandy
Watch the evolution of the superstorm
Raw video: Long Island flooding

Second, the core of Sandy -- the part that will look and feel like a hurricane -- has remained intact, even as cooler and drier air from the United States wraps around it. Thus, Sandy has each of the worst features of both kinds of storm: a small core of hurricane-force winds around its center, and a broad expanse of gale-force winds extending hundreds of miles outward that will batter the shorelines for several days.

Why did this happen?

It was simply a matter of positioning.

Sandy arrived east of Florida at exactly the right time and place to get the maximum benefits from its interaction with the dip in the jet stream. As a result, Sandy became large enough to influence that system as well, and the two will wrap around each other into a single, deep cyclone, 800 miles across, extending from the ground to 40,000 feet in the sky. This will add to the duration of the event as the circulation takes several days to wind down over Pennsylvania and New York.

Opinion: Climate change raises stakes for coast

As for whether Sandy is a "Superstorm," perhaps we should refrain from such a designation until after the event.

There was already a "Superstorm" in March 1993 -- a nor'easter that dumped snow from New Orleans to Canada. There was the Halloween Storm of 1991 -- later known as the Perfect Storm -- which, like Sandy, also grew from the confluence of a large extra-tropical cyclone and a hurricane (which, unlike Sandy, was destroyed in the process). And there was the Blizzard of '78, the Eastcoaster of 1996, and others.

Sandy will take its place in history, but we will not know what that place is until many days have passed.

Follow us on Twitter @CNNOpinion

Join us on Facebook/CNNOpinion

The opinions expressed in this commentary are solely those of David Nolan.

ADVERTISEMENT
Part of complete coverage on
updated 2:19 PM EDT, Fri October 31, 2014
As a woman whose parents had cancer, I have quite a few things to say about dying with dignity.
updated 9:04 AM EDT, Fri October 31, 2014
David Gergen says he'll have a special eye on a few particular races in Tuesday's midterms that may tell us about our long-term future.
updated 10:52 AM EDT, Fri October 31, 2014
What's behind the uptick in clown sightings? And why the fascination with them? It could be about the economy.
updated 9:01 AM EDT, Fri October 31, 2014
Midterm elections don't usually have the same excitement as presidential elections. That should change, writes Sally Kohn.
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
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT