Today is Historically the Peak of the Hurricane Season
September 10, 2010
By Ken Kaye, Sun Sentinel, Fort Lauderdale, Fla.
Sept. 10--It's here, the peak of storm season, the day hurricanes are most likely to be swirling in the Atlantic.
Since 1851, when records were first kept, more hurricanes have been in existence on Sept. 10 than any other date. In that 159-year period, there have been 86 hurricanes on Sept. 10. The next closest date: Sept. 9, with 83 hurricanes.
"It's the day, historically, we see the most overall activity," said James Franklin, top hurricane specialist at the National Hurricane Center in Miami-Dade County.
Although it is expected to steadily strengthen, what once was Tropical Storm Igor likely will not follow tradition and grow into a hurricane by Friday. The system deflated into a tropical depression as it moved west in the eastern Atlantic on Thursday.
The long-range forecast calls for Igor to arrive in the central Atlantic in five days as a Category 2 hurricane with sustained winds of about 100 mph. From there, models indicate it might turn north. If that holds, the risk to the U.S. East Coast would be reduced.
Although it's not the midpoint of the six-month season, Sept. 10 is almost dead center of the meanest stretch of the season, from mid-August through the first week in October.
During that seven-week period, the waters in the eastern Atlantic tend to be at their warmest and the winds at their lightest, allowing hurricanes to spawn near the Cape Verde Islands. It is when conditions are at their ripest for storms to bulk up, Franklin said.
"Cape Verde hurricanes do tend to be the stronger storms," he said.
On the other hand, storms aren't more likely to be at their maximum strength on Sept. 10, said Phil Klotzbach, the Colorado State University climatologist who develops seasonal predictions with William Gray.
"In general, more major hurricanes occur during the month of September than in any other month," Klotzbach said. "But I don't think that storms on Sept. 10 necessarily are going to be more intense than storms, say, 10 days earlier or 10 days later."
Extremely intense hurricanes can develop at any time between July and November. Consider that Wilma was the most intense hurricane ever, packing sustained winds of 185 mph while it was in the western Caribbean in mid-October 2005. And Paloma burgeoned into a Category 4 system with 145 mph winds while in the Caribbean in early November 2008.
Furthermore, hurricanes aren't more likely to strike land on Sept. 10; none have hit the U.S. coast on that date in the past 20 years. However, Category 4 Hurricane Donna struck the Florida Keys on that date in 1960, killing 12 and causing about $2.5 billion damage in 2010 dollars.
On average, by Sept. 10, six named storms have emerged, including three hurricanes, one with winds greater than 110 mph. So far, this season is progressing faster than normal, with nine named storms, including three hurricanes, two intense.
In 10 of the past 15 years, a hurricane was swirling on Sept. 10. Major hurricanes were churning on that date in four of those years, including 2004, when Ivan was at Category 4 strength with sustained winds of 150 mph. It went on to strike Alabama as a Category 3, pummeling Pensacola at the same time.
After Sept. 10, the tropics slowly start to wind down. The Atlantic waters start to cool, and the winds begin to pick up, making storm formation more difficult. By early October, tropical waves coming off the coast of Africa are less likely to develop.
"The favored location for formation shifts to the west, in the Gulf and Caribbean," Franklin said.
During the middle of October, there is a second, though less-vigorous peak. Two tropical systems, including a hurricane, on average form in that month. And it isn't unheard of to see tropical activity as late as December.
That is why emergency managers urge residents not to let down their guard after the peak passes.
"The storm season is six months long," said Bill Johnson, Palm Beach County emergency management director. "So you need to be prepared, vigilant and informed throughout the season."
Ken Kaye can be reached at kkaye@SunSentinel.com or 954-572-2085.
Copyright (c) 2010, Sun Sentinel, Fort Lauderdale, Fla.
Story Image: This is a satellite image showing Category 4 Hurricane Earl churning through the western Atlantic on September 2, 2010. (NASA, AP)
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