#613 Postby Ivanhater » Sun Oct 09, 2005 2:41 pm
Ivan strong by any measure
Winds say Category 3, but damage says Category 4
Lesley Conn
@PensacolaNewsJournal.com
The National Hurricane Center later this month is expected to officially classify Hurricane Ivan as a Category 3 storm.
But it might have had an impact more like a Category 4.
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Ivan's aftermath
In the early morning hours of Sept. 16, 2004 Hurricane Ivan roared onto shore just west of Pensacola. This section covers the aftermath of that devastating storm. Use the drop-down menu below to view articles from the section.
Select a story "You got hit the hardest." 'Monster of a hurricane' left horror in its wake 911 calls illustrate rising water, panic (with audio) Surging water terrified area Hurricane Ivan by the numbers Recovery still a dream in a beautiful place to live Insurance not enough for many Bay Street residents lose neighborhood Ivan strong by any measure Flood zones create confusion Tourism rebuilding with the beaches Ivan's lesson: Build better, stronger Some challenges we face after Ivan
Ivan's destructive water
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In harm's way
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Multimedia: Ivan's storm surge
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View hundreds of photos from the storm and the clean-up efforts.
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Special Report: The Insurance Storm.
Read our Heroes of Ivan series.
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The rating is based on sustained wind speeds calculated at 120 miles per hour. If that seems insufficient to reflect the devastation that still surrounds so many people in the Pensacola Bay Area, it may very well be, some hurricane experts acknowledge.
Ivan's enormous size, its significant storm surge and its low central pressure aren't the determining factors in setting its final category number. Yet all three combined to create a storm so punishing that Ivan is listed ninth on the list of the Top 10 Insured Loss Events in World History, according to the Insurance Information Institute.
Calculated losses of $4.3 billion statewide do not include losses for flood damage, which have not been released by the Federal Emergency Management Agency.
So why is wind speed used to establish a category?
Mostly because it is readily definable and easily measurable, said Frank Lepore, spokesman for the National Hurricane Center. Storm surge, for example, is not as easily measured and is affected greatly by the continental shelf, which can vary by hundreds of miles from one location to the next.
And because a hurricane's strength is of interest to a broad array of people, whether the merely curious or to building and insurance officials, it helps to have simple, specific parameters.
One measurement "could not possibly define the effects for every geographic effect,'' Lepore said. "The Saffir-Simpson scale is probably best for general effect, not specific effects. It's more of an indicator, not a definitive reflection.''
One persistent shortcoming of gathering specific wind information, however, is that gauges directly in the path of a storm tend to fail.
That happened with Ivan, leaving the bulk of recorded data to come from the weaker, western side of the storm.
In Ivan's case, the strongest winds likely swept over the Perdido Key and Grande Lagoon area, where there are no gauges, said National Weather Service senior meteorologist Gary Beeler, who is based in Mobile.
"I think we missed (recording) the maximum winds,'' he said. "The pressure and the surge was more conducive to a Category 4 storm.''
And at landfall, Ivan's minimum central pressure was 943 millibars, which falls within a Category 4.
The extent of Ivan's damage was plainly visible during aerial reviews after the storm.
Also obvious to hurricaneexperts was how much wider its impact was than that of Hurricane Charley, a Category 4 storm that struck Aug. 13 near Punta Gorda and cut through Orlando and Daytona Beach before plowing back into the Atlantic.
"Charley had the strongest winds at 145 mph, but it was extremely narrow,'' said Abby Sallenger, a research oceanographer for the Center for Coastal and Watershed Studies, a U.S. Geological Survey research facility in St. Petersburg. "With Ivan, you could fly for 50, 60, even 80 kilometers, and you could see breaches and (barrier island) cut-throughs.''
Storm surge and extreme wave action wrought most of that damage.
Hurricane Opal, the 1995 storm that made landfall at Pensacola Beach, was ranked as a Category 3 storm, too. Its highest sustained winds were recorded at 115 mph.
But Opal is listed as the fifth-most expensive U.S. hurricane, with damages of $3 billion.
Water, not wind, was largely to blame with Opal, too.
Opal heaved several feet of water onto Pensacola and Navarre beaches, cutting paths to Santa Rosa Sound, flattening homes and swallowing long stretches of road.
But comparisons of peak storm surge for Opal and Ivan show it was significantly higher for Ivan.
In Pensacola Pass, at Fort McRae, the surge during Opal measured 7.5 feet; Ivan was 9.7 feet. Another tide gauge at Pensacola Bay off downtown Pensacola showed a surge of 6.2 feet for Opal; for Ivan, 10.2 feet. And in Gulf Breeze, Opal's surge was recorded at 6.3 feet; Ivan was at 10.3 feet.
And where Opal's worst damage was limited largely to the beaches on Santa Rosa Island, Ivan's surge smashed past the island and kept moving inland, swamping homes from Perdido Key to Oriole Beach before moving as far north as Floridatown, north of Interstate 10 in Santa Rosa County.
Like Charley, Opal was a compact storm. Shortly before it made landfall, a reconnaissance plane measured its eye at 10 nautical miles. Ivan's eye was about 20 miles wide, and hurricane-force winds extended 120 miles.
That created waves and surge from Orange Beach, Ala., to Destin.
"Ivan's surge,'' Beeler said, "was the worst surge in modern history in Escambia, Santa Rosa and Baldwin (Ala.) counties.''
It rivals the 1926 hurricane, which also made landfall near Gulf Shores, Ala. Once again, the strongest winds and surge - to the east of the storm - swept over the Pensacola area. The storm tide, which includes tide levels and surge, reached a peak of 9.4 feet at Pensacola, 10.4 feet at Fort Pickens and 14 feet at Bagdad.
As technology continues to improve, hurricane analysis is becoming more sophisticated and more accurate, especially where wind readings are concerned.
Hurricane Andrew, the 1992 storm that made landfall near Miami, was reclassified from a Category 4 to a Category 5 storm in 2001.
Wind instruments that are dropped from the reconnaissance airplane and use a global positioning system to record wind speed, barometic pressure and water vapor provide more detailed information closer to the land, Lepore said.
That information was not available in 1992. Analysis determined that wind speeds closer to land did not drop as much as had been calculated. When Andrew's winds were recalculated, winds were about 17 miles an hour faster. The difference was enough to bump it into the highest storm category.
The Hurricane Center is reviewing all past storms with the new wind-speed formula.
Ivan's wind classification, while still under review, should not change significantly, hurricane analysts said.
In weather experts' eyes, that does little to diminish its impact.
"If people were surprised at the amount of water that showed up in their front lawn, I suspect they weren't aware of what a Category 3 or 4 storm could do locally,'' Lepore said. "A Category 3 or higher only represents 20 percent of storms, yet that represents 80 percent of all damages."
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and i have a lot of pics to show you of "superficial damage" i wish they banned you for good before , anyway on with an intelligent debate.....i know the data is very limited on ivan so its not easy to say, thats why the debate has been going on for so long with researchers, but for the pcola area, are those the only reports, from the station that broke at NAS?
