January 4, 2000
Storms That Surprised Europe Show Forecast Limits
Related Articles
Storm-Battered France Assesses Human Toll and Cleanup Costs (Dec. 30, 1999)
22 Die as France Is Hit by 2nd Part of Weather's One-Two (Dec. 29, 1999)
The New York Times on the Web: Science
Forum
Join a Discussion on The Environment
By SUZANNE DALEY with WILLIAM K. STEVENS
ARIS, Jan. 3 -- The day before
the first of two fierce storms touched
down on France's west coast last
week, streaking across the country
and causing heavy damage in other
parts of Europe as well, meteorologists here predicted stormy weather,
but nothing out of the ordinary.
|
 
AFP; AP
|
Meteorologists failed to forecast the intensity of storms that hit France last week. The roof of the cathedral at Rouen was damaged, and 10,000 trees were uprooted in the royal park at Versailles.
|
There was no warning of the gale
force winds that tore down one-quarter of the country's electric grid,
uprooted thousands of trees and
damaged some of the country's best
known historic monuments, including Notre Dame and Versailles.
A week later, France is still struggling with the damage, with more
than 400,000 homes yet to get power
back.
So in this age of satellite weather
pictures and computer projections,
how could these storms have taken a
continent so completely by surprise?
Are fierce and unpredictable storms
part of a new weather pattern related to global warming? Are there
more to come?
Experts say that predicting weather in Europe remains particularly
difficult, despite the latest technology. Most meteorologists rely heavily on computerized models that
must be fed a great number of up-to-the-minute weather observations.
The problem is that many of Europe's weather patterns come off the
Atlantic Ocean, where observations
are sparse. Key factors may not be
detected, so the models, never fool-proof, have a greater chance of failing.
"The problem with this storm is
that it came like a cannon shot, very
fast and very straight, so there wasn't much time to collect anything,"
said Patrick Galois, a forecaster
with the French national weather
service, Météo.
"But it's always hard to get good
information over the Atlantic. There
are boats out there that send wind,
temperature and pressure information and we get information from
satellites, too, but they look down
over what is going on from very high
up. We just don't get a good picture
of everything going on over the sea."
Mr. Galois said new satellites to be
launched later this year might improve the information that went into
forecasting.
Severe fall and winter storms are
not rare in Europe, Mr. Galois said.
In late October 1987, for instance, a
storm with 100-mile winds paralyzed
London, killing 13 people and destroying some 1,000 trees at Kew
Gardens, the world's oldest and most
famous arboretum.
In early 1990,
storms with hurricane-force winds
slashed through Western Europe
three times in six weeks, killing
more than 140 people and causing
perhaps a billion dollars in damage.
But, like other experts, Mr. Galois
pointed out that the intensity of the
two most recent hurricanelike
storms was rare, and that the appearance of two such storms within
48 hours was even more so, a phenomenon seen perhaps once in a century. Mr. Galois said the first storm
took a mere 24 hours to cross the
Atlantic. Usually, weather patterns
take 48 hours.
Whether or not global warming
will be a factor in creating more such
storms remains an open question.
Mr. Galois said not enough information was yet available about what
added warmth might touch off.
"It does not create storms, but
maybe it will have an effect on
them," Mr. Galois said. "If the
oceans are warmer, that could be
another source of energy out there
that might intensify a storm."
Some climatologists say that if the
earth's atmosphere warms as predicted, storms will become more intense. But while there is some evidence that rainstorms have become
heavier in some parts of the world,
there is no solid indication of stronger wind storms. At any rate, experts
say, no specific weather development can yet be attributed to global
climate change.
The two storms that struck Europe beginning Dec. 26 are the kind
that develop along a front, or boundary, between cold arctic air and
warmer southern air that circles the
globe. Above this boundary is the jet
stream, the high altitude river of air
in which most storm systems are
embedded, and that carries them on
a general west-to-east course.
In this case, meteorologists say,
the jet stream was classically placed
and of classic strength to promote
the development of superstorms. It
was a "fast, ripsnorting jet stream
right straight west to east, across the
Atlantic from the U.S. to Europe,"
said Jim Wagner, a meteorologist
with the federal Climate Prediction
Center at Camp Springs, Md. This is
the kind of atmosphere setup that
can cause a storm to blossom explosively if one should develop.
The faster the jet stream, the more
air it whisks away from the area of a
developing storm below it. This further lowers the air pressure within
the storms (by taking air away from
them). The lower the pressure, the
faster air rushes in from outside the
storm to try to equalize things. This
rush of air is wind, and the lower the
storm's pressure, the stronger it is.
Relatively warm air off the ocean
also imparted extra energy to the
system.
Meanwhile, farther south, an unusually strong high-pressure system
made the difference between the center of the storm and the outside air
even greater, and the winds became
even stronger -- in this case, as
strong as a moderately severe hurricane. All these factors played a role
in producing the winds that did most
of the European damage.
The storms themselves were relatively small vortexes of wind and
precipitation circling counterclockwise around a central core. It was
the sustained winds of these vortexes, much like those that circulate
around a hurricane, that blasted the
continent. Some tornadoes might
have spun off, said Todd Miner, a
meteorologist at Pennsylvania State
University. But if they did, he said,
they were not the major problem.
The first storm hit northern
France hardest. The second tore
through the southern half of the
country. Together they caused perhaps as much as $4 billion worth of
damage, according to some insurers,
and killed 88 people in France alone.
The national electricity company,
EDF, said today that the task of
restoring power was proving more
difficult than expected and was hampered by bad weather. Fog prevented some helicopters from taking off.
Snow and flooding were also making
repairs more difficult.
But lack of electricity was not the
only problem. The Education Minister, Claude Allegre, announced that
about 40 schools would remain closed
because of damage when classes resumed on Tuesday after the Christmas and New Year's holiday. About
900 of France's 11,400 schools were
damaged by the storms.
