Hurricane Almanac 2006: The Essential Guide To Storms Past, Present, And Future - Softcover

BRYAN NORCROSS is the on-air hurricane analyst for CBS News, appearing nationally on the CBS Evening News and other programs. He is also director of Meteorology at WFOR-TV, the CBS station in Miami. His award-winning coverage of Hurricane Andrew in 1992 made him a national figure.

Chapter One 

Hurricanes Today
 
The Hurricanes Return--1995-2005
 
Hurricanes come in cycles. A casual glance at a list of active hurricane seasons shows clusters of activity in the 1880s-1890s and 1920s-1960s, while the early twentieth century and the 1970s, 1980s, and early 1990s look relatively calm. Another active period started in 1995 and continues today.
 
Dramatic economic growth, immigration, increasing longevity, and other factors coincided with the hurricane downturn of the late 1960s to mid-1990s. The effect can be seen throughout the coastal zone. Would 18 million people be living in Florida today if hurricanes had continued coming at the rate they occurred in the late 1940s and in the last two years? I wonder.
 
Unfortunately, the people in government with the responsibility for seeing that citizens are safe during disasters were (and are) not very good students of history. Most coastal areas, including the state of Florida, were developed without regard to the hurricanes of the past and without protection from the hurricanes to come. Thus, future disasters are guaranteed.
 
Hurricane cycles correlate with the natural fluctuation in the temperature of the ocean.
 
This chart compares the Atlantic Ocean water temperature to normal. The match with hurricane activity is remarkable. Notice that the late 1800s and the period from the late 1920s to the late 1960s show warmer than normal temperatures. They were active hurricane periods as well. The swing in temperature is only about plus or minus one degree Fahrenheit, but the amount of energy that slight difference makes spread out over the entire Atlantic Basin is significant. See "Global Warming and Hurricanes," page 74.
 
Hurricane Season 2005
 
Every hurricane has its own personality, and every hurricane season does as well. Anytime there are a lot of landfalling storms, let alone a record-setting season like last year's, lessons abound--big and small. In my opinion, the biggest lesson of the hurricane season of 2005 was: The worst does happen!
 
In case after case people suffered and property was destroyed because someone--a governmental body or official, a business owner or a private citizen--decided to ignore hurricane history, ignore hurricane research, and hope for the best. Thus the lesson. Hoping does not hold back wind and water.
 
The two most remarkable storms of 2005 were Hurricanes Katrina and Wilma. That's not to ignore or discount the effects of Dennis, Emily, Ophelia, Rita, Stan, Gamma, and the rest. In a normal hurricane season, any one of those storms would be memorable. But Katrina and Wilma rose above the pack in this extraordinary season of storms.
 
An easy-to-forget aspect of the 2005 season is that none of the record-setting hurricanes formed in the deep tropics. Through history, most of the "great" hurricanes have formed well east of the Lesser Antilles. From there they have time to organize and gain strength. The fact that the traditional breeding ground for big, powerful hurricanes was not fertile in 2005, and yet fifteen hurricanes formed, gives us pause. See "Hurricane Season 2006," page 15.
 
Researchers still haven't determined for sure why the deep tropics were shut off in 2005. A reasonable explanation might have to do with the "waviness" of the weather pattern around the earth. Rarely are all parts of the Atlantic Basin in a favorable mode for storm development at the same time. Normally, when one part is favorable, other parts are not. In 2005, however, the weather pattern in the Gulf of Mexico and the western Atlantic was ideal for strong storms from June to December. Perhaps the favorable area just never shifted, so the eastern Atlantic stayed in an unfavorable mode. More research remains to be done.
 
Thursday, August 29, 2005--Hurricane Katrina
 
Katrina was a hurricane catastrophe . . . in southern Mississippi. In Louisiana, it was a healthy hurricane hit . . . and a levee design/engineering/maintenance/operation debacle . . . compounded by a FEMA fiasco . . . that led to human suffering on a scale that we had not seen in the United States in modern times. Everyone involved, from Washington, D.C., to Louisiana, should be ashamed and embarrassed. We should all be disgusted with our governments.
 
Katrina's winds in New Orleans. There is very little, if any, reason to think that most of New Orleans experienced more than a category 1 hurricane. For the city it was nowhere near a historic hurricane event. Here is the evidence:
 
•           The only wind in New Orleans over category 1 strength was measured on the far east side of the city, and it was 96 mph, the lowest number in the category 2 range. All of the other measurements--although there weren't many--were low-end category 1 or tropical storm force.
 
•           An anemometer in the middle of Lake Pontchartrain that survived measured a peak sustained wind of 78 mph. While this may not have been the highest wind over the lake, it should be reasonably representative. And it's low-end category 1.
 
•           The water did not top the Lake Pontchartrain levee. Originally designed for a category 3 storm surge, the levee at its existing height would likely only withstand a category 2, according to research by a group at Louisiana State University. That levee, along with all of southern Louisiana, is sinking. So the evidence is that the storm surge rose to less than category 2 levels.
 
•           The wind rating of the roof shingles on most of the houses in New Orleans was 60 mph. Most of the shingles stayed on.
 
•           A rough estimate of the wind on the left side of the storm (the New Orleans side of Katrina) is 93 mph.
 
 
Follow me now. There are two components to the maximum wind speed in a storm: the intrinsic wind of the counterclockwise circulation and the contribution from the forward movement of the system. As Katrina moved north toward the Gulf Coast, the total wind speed on the right side included the forward speed of the storm. The wind speed on the left side was the intrinsic wind in the storm minus the forward speed. Therefore, the wind on the left is the right-side wind (the maximum wind) minus twice the forward motion.
 
So, as an approximation, the maximum wind on the left side--the New Orleans side--of Katrina was at most 93 mph, a strong category 1. It's a rough estimate, to be sure, but the calculation adds to the case that the winds were not the cause of the catastrophe.
 
Katrina's storm surge in East New Orleans. New Orleans was subject to storm surges coming from two directions, each caused by two different factors. To understand what happened during Katrina we have to look at them separately.
 
To the east side of the city, a massive storm surge was generated by Katrina's winds, which the day before, had been 165 mph. That water was forced into the "corner" formed by the southeastern Louisiana and southern Mississippi coasts and then up the Mississippi River-Gulf Outlet Canal (the MR-GO) toward the city. Under the pressure of this water, the levees on both sides of the canal failed, inundating New Orleans East and St. Bernard's Parish. The high-speed water continued west into the Industrial Canal, where the levees also collapsed, putting the Lower Ninth Ward under water.
 
The MR-GO Canal had previously been identified as a threat to the eastern part of the city. As water funnels into a narrow canal the power...