Recent Hurricanes:
Hurricane Dennis
- July 10, 2005
Hurricane Ivan
- September
16, 2004
Hurricane Dennis
follows Ivan's path . . .
The core drilled the Florida Panhandle and the Alabama coast with
estimated 120 mph winds, officially making landfall on Santa Rosa Island
July 10, 2005 at 2:25 p.m. That made it a major Category 3
hurricane and put it squarely in the same area pounded by Ivan 10 months
earlier.
Dennis was the strongest hurricane to ever directly strike Florida in
July but also one that moved with charitable swiftness at about 18 miles
per hour. Had Dennis been traveling at six miles per hour, it would have
been more catastrophic than Ivan.
Why Hurricane
Dennis let us off lightly . . .
Willie Drye
for National Geographic News, July 11, 2005
Hurricane Dennis, one of the most intense July hurricanes on record in
the U.S., came ashore yesterday afternoon at Santa Rosa Island, Florida,
just off Pensacola.
Despite its 120-mile-an-hour (190-kilometer-an hour) winds, Dennis's
U.S. landfall was considerably weaker than expected, largely due to
unusually cool seas and the "choking" effect of thunderstorms that were
spawned by the hurricane.
The small eye of the compact, fast-moving storm struck about 30 miles
(48 kilometers) east of where Hurricane Ivan made landfall in Alabama
last fall.
Residents on the Gulf of Mexico coast had feared that Hurricane Dennis
would inflict massive damage and had prepared for a battering. About
500,000 people moved inland as Dennis approached. In Alabama, state
officials stopped southbound traffic along a stretch of Interstate 65
during the weekend so all lanes could be used for northbound traffic
leaving the city of Mobile.
But the storm struck a less populated area of Florida's Panhandle, and
its smaller size reduced the area that was exposed to its strongest
winds. Still, as many as half a million people today are without power
from Mississippi to Florida.
No deaths were reported in the area where Hurricane Dennis came ashore,
and the storm weakened to a tropical depression as it moved inland
Sunday night. But the U.S. National Hurricane Center warned Monday
morning of possible "significant flooding" as the remnants of Dennis
move slowly over the U.S. South during the next several days.
Dennis was the second major hurricane to strike the storm-battered Gulf
Coast in less than a year and the fifth hurricane to strike Florida
during the same period. And the hurricane barely waited for tropical
storm Cindy to clear out before it arrived.
When Cindy departed Thursday, coastal residents from Louisiana to the
Florida Panhandle scarcely had time to replenish their supplies before
hunkering down for an even worse pounding from Dennis.
Could Have Been
Much, Much Worse
As bad as Hurricane Dennis was, however, it could have been much, much
worse.
After lashing Haiti and other Caribbean nations, the storm came ashore
on the southern coast of Cuba with winds approaching 150 miles (240
kilometers) an hour. At least 20 deaths were reported as a result of the
hurricane's rampage across the Caribbean, which began July 5.
Crossing Cuba disrupted the hurricane's organization, however, and by
the time it passed over Havana and emerged in the Gulf of Mexico, its
strength was greatly reduced.
At 10 a.m. on Saturday, as Dennis was beginning its journey across the
Gulf, its strongest winds were 90 miles (145 kilometers) an hour. The
weakened hurricane inflicted less damage than expected as its eye passed
offshore of the Florida Keys.
Jeffrey Pinkus, mayor of the Keys city of Marathon, said, "Ninety-nine
percent of the damage here is just landscape damage. I haven't heard
anybody say there was a storm surge problem." Caused by strong winds, a
storm surge is an abnormal rise in sea level that can lead to coastal
flooding.
But more than 500 miles (800 kilometers of warm ocean water lay ahead of
Dennis. Hurricanes draw their power from warm water, and the Gulf of
Mexico was prime fuel for Dennis.
The hurricane steadily regained strength as it moved northward. By 6
p.m. Saturday its winds had increased to 115 miles (185 kilometers) an
hour, making Dennis a major hurricane.
But between then and 4 a.m. Sunday, Dennis underwent a meteorological
phenomenon often referred to as bombing out. In only ten hours the
storm's strongest winds leaped to 145 miles (230 kilometers) an hour. By
early Sunday morning city officials in Mobile were confronting a
potential catastrophe.
At that time forecasters expected Dennis to charge into Mobile Bay. The
bay would have acted as a giant funnel, channeling a storm surge of
perhaps 17 feet (5 meters) into downtown Mobile. The surge would have
flooded a part of the city where many residents hadn't evacuated,
because they either had no place to go or were unable to leave.
Mobile officials called in the city's bus drivers early Sunday morning.
All residents who wanted to leave were taken to a shelter on the west
side of the city.
"It was a phenomenal effort," Mobile fire department captain Debbie
Bryars said. "The emergency-management department got the drivers to
come in and got the word out about the evacuation."
Hundreds of people were moved out of harm's way, Bryars said.
But as Dennis bore down on the narrow Alabama coast Sunday afternoon,
several factors intervened to diminish its winds and drag it away from
Mobile Bay.
How Dennis Was
Defanged
Randy McKee, chief meteorologist at the National Weather Service's
Mobile office, said Dennis's power was diminished when it went through
an "eye wall replacement."
This process often happens to very intense hurricanes, such as Dennis,
when a second wall of intense thunderstorms begins forming around the
storm's existing eye. The eye wall acts as a giant noose, choking the
hurricane's momentum and reducing its winds.
The thunderstorms forming and dissipating around Dennis's eye also
pulled the storm off its Mobile-bound course.
The thunderstorms had the same effect as putting a small weight on a
spinning top, McKee said. "If you had the top spinning perfectly and you
put a little weight on one place, it would affect the top's path," he
said.
"That little hiccup in there was enough to move the hurricane's landfall
from Mobile Bay to the east," McKee said.
Hurricane Dennis ran into another impediment as its eye drew within 150
miles (240 kilometers) of the Alabama coast. At that point the hurricane
began crossing over seas that had been churned up by Tropical Storm
Cindy late last week. The churning had cooled the water, depriving
Dennis of the warm seas it needed to maintain its fearsome winds.
So between 9 a.m. and 3 p.m. Sunday, Dennis became a different
hurricane. It was still potent but not quite the monster it had been,
and it was headed away from the heavily populated cities of Mobile and
nearby Pensacola, Florida.
A Storming
Trend?
Meteorologists have predicted that the 2005 hurricane season—which runs
from June 1 to November 30—will continue a ten-year trend of unusually
active seasons.
The hurricane season usually becomes busy in mid-August and reaches its
peak around September 10. But so far this year, four named storms
already have formed. That's the first time on record that this has
happened, and the usual peak of the hurricane season is still two months
away.
Willie Drye is the author of Storm of the Century: The Labor Day
Hurricane of 1935, published by National Geographic Books
Source:
nationalgeographic.com
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Dennis drills the Florida
panhandle with
120-mile-an-hour
winds Sunday, July 10, 2005.
This sign appeared in front
of a home on Olive Road appealing to Gulf Power. It appeared to be
working as power trucks moved into the area working on the lines.
Navarre, Fla. -- John Larker, real
estate developer wades through flood waters after surveying the damage
to his home, shown in the background, caused by Hurricane Dennis. Larker and his wife Cathy,
finished repairing damage from last year's Hurricane Ivan only five
weeks before Dennis arrived.
Aerial photos from Santa
Rosa County
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