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By Stan
Finger - The Wichita Eagle
 The most
tornadoes in a seven-day span in recorded history. A June
hailstorm that dropped a record-setting cantaloupe of ice
on Nebraska. A tornado two days later in South Dakota that
produced a drop in barometric pressure far greater than
weather experts believed possible.
Winds of
120 mph, equaling a powerful hurricane, that slammed Wichita's
McConnell Air Force Base in late August. Even in Kansas,
where the wind is part of the state's personality, that
turned heads.
What the
heck is going on?
The answer
depends on who's talking. Some experts have suggested for
a while now that, because of global warming, severe storms
are going to become more frequent and more violent. Others
say the only thing that has really changed is our enhanced
ability to notice and understand what Mother Nature can
do.
"You
have to keep things in perspective," said Dan McCarthy,
director of the National Oceanic and Atmospheric Administration's
(NOAA) Storm Prediction Center in Norman, Oklahoma
"Whenever
we hear someone say, 'We're seeing things that we've never
seen before,' " McCarthy said, the thing to ask is, "Relative
to what?" Just because people are seeing something
for the first time doesn't mean it has never happened before.
It just means those people haven't seen it. Many records
now being kept go back only a few decades, offering a limited
base from which to draw comparisons.
Sometimes
the surprises can be linked to new technology. Scientists
have been trying for years to put small sensors in the
path of a tornado, hoping the sensors would get sucked
up and provide data on what goes on inside the storm.
That is
just what happened on June 24 in South Dakota.
"They
measured over a 100-millibar pressure drop" in the
atmosphere, said Jon Davies, a research meteorologist based
in Wichita. "That's larger than what had been previously
thought possible or previously recorded."
Drops in
barometric pressure have long been associated with tornadoes,
but the June 24 drop was almost twice the accepted norm.
Of all the eye-catching severe weather this summer, the
Aug. 23 straight-line winds at McConnell are likely the
easiest to explain, said Mike Kreyenhagen, a meteorologist
with the National Weather Service's Wichita office.
A layer
of cool, moist air was sandwiched between two layers of
very hot air. Temperatures in Wichita had reached or exceeded
100 degrees for the eighth straight day. Cool air naturally
sinks, Kreyenhagen said. Because the air beneath it that
night was so hot, offering a strong contrast, "once
the cool air breaks through, it just howls down," he
said.
The winds
destroyed a pole barn, uprooted several trees and damaged
roofs at McConnell.
Explanations
are proving tougher to come by for what happened June 22
in Nebraska just north of the Kansas state line. Two powerful
thunderstorms erupted 50 miles from each other and pretty
much set anchor, said Todd Holsten, a meteorologist in
the National Weather Service office in Hastings, Neb.
One cell
produced a foot of rain, hailstones as large as 2.5 inches
in diameter and eight tornadoes -- including one that killed
a person in Deshler, Neb. The other cell, farther north,
hit Aurora with hailstones as large as cantaloupes but
produced not a single tornado.
"I
don't know why the Aurora storm didn't produce a big, honking
tornado," said Davies, who tracked the storm cell
but avoided its center because he could tell from the radar
that "if we punch the core, we're probably going to
lose a windshield on this one."
He was
right.
One hailstone
from the Aurora storm measured 7 inches in diameter and
18.75 inches in circumference, seemingly earning the title
of largest hailstone ever recorded in the United States,
displacing a stone that fell in Coffeyville in 1970. But
McCarthy said a search of storm data at the Storm Prediction
Center unearthed a report of a hailstone nearly 10 inches
in diameter that fell in
Indiana on May 6, 1961. That's bigger than a basketball.
Davis said
only a half-dozen storms in a database of 550 storms he
has accumulated from the past 11 years had as much instability
as the Deshler storm. Instability typically translates
into severe weather of some kind, such as hail or tornadoes.
The Deshler
storm had twice as much instability, Davies said, as the
supercells that produced the F-5 tornado that struck Andover
in 1991, or the F-4 that hammered Hoisington in 2001. Yet,
the Deshler tornado only rated an F-2. "There'll be
a lot of future research papers that come out of those
two storms" in Nebraska, Holsten said. "There's
a lot of oddities on that day."
As radar
has improved, meteorologists can look inside a storm to
see activity at different levels, allowing them to monitor
structure, development and areas of rotation. But for every
answer, said Dick Elder, chief meteorologist at the Wichita
office of the National Weather Service, more questions arise. "It's just
like opening one door to see all the wonderful things, but
understanding there's still another door to be opened," he said.
At the
National Weather Association conference in Oklahoma City
three years ago, Elder heard a presentation on the effect
of global warming on weather patterns. Thanks to fossil
fuels, climatologists say, we have put more carbon into
the atmosphere in the past 50 years than in the previous
million years.
"Is
that carbon going to do anything?" Elder asked. "Everyone
says 'yes.' "
While one
climatologist used computer-generated models to suggest
that summer heat indexes would often reach 150 in Washington,
D.C., by the year 2050, another offered an explanation
that makes more sense to Elder. "Mother Nature is
a very resilient old gal," Elder said, recalling the
presentation. "She's going to do everything she possibly
can to keep our planet as much as we perceive it now."
The extra
carbon in the atmosphere traps more heat and more moisture,
which translates into more energy. The most efficient way
for the atmosphere to maintain equilibrium is to generate
storms. With more energy and instability on hand, there's
more fuel for the storms that fire up. That means they
can be bigger and nastier.
"We're
going to see more of those" giant storms, Elder said.
The week
of May 4-10 set an all-time record for most tornadoes in
one seven- day period. By an unofficial count, 386 tornadoes
touched down in 19 states, killing more than 40 people,
including seven in Kansas. The one-week total more than
doubles the previous record, set in 1999. But tornado records
only go back to 1950.
Davies
isn't ready to pin this year's spate of eye-popping storms
on global warming. In fact, he's not sure they can be attributed
to any particular phenomenon, such as El Nino. But they're
definitely worth a good look, he said.
"Mother
Nature isn't slowing down any," he said, "and
maybe she's picking her step up."
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