http://www.washingtonpost.com/wp-dyn/content/article/2008/05/08/AR2008050803063_pf.html
George Cressman; Modernized Weather
Service Forecasting
By Matt Schudel
Washington Post Staff Writer
Friday, May 9, 2008; B07
George P. Cressman, 88, a former National Weather Service director
who took the lead in applying computers to meteorology and helped
change weather forecasting from a form of cloud-gazing guesswork to a
codified science, died April 17 at the National Lutheran Home in
Rockville. He had Alzheimer's disease.
In the 1950s, Dr. Cressman developed the first program that could
produce accurate and reliable forecasts prepared by computer, which led
to a monumental change in how weather is predicted and brought
meteorology into the computer age.
As director of the Weather Service from 1965 to 1979, Dr. Cressman
expanded the number of local weather radars, developed a nationwide
weather radio network and introduced systems to provide early warnings
of tornados and flash floods. He also made important contributions to
cooperative meteorological efforts around the globe.
"He really, truly was a giant in meteorology," said Richard E. Hallgren,
who succeeded Dr. Cressman as National Weather Service director.
"Worldwide, he was extraordinarily well known. He is one of the few
who have contributed to so many things."
In the late 1940s, meteorologists were among the first scientists
attempting to harness the new technology of computers. They had little
sustained success until Dr. Cressman was named director of the federal
Joint Numerical Weather Prediction Unit in Suitland in 1954. Using an
IBM 701 computer, he recorded the weather conditions at equally
spaced points around the world, then devised a program that allowed the
computer to produce forecasts derived from the cumulative data.
"At the time, that was a major breakthrough," said Ron McPherson,
executive director emeritus of the American Meteorological Society.
"Before that was done, forecasting was mostly an art" based on
extrapolations from hand-drawn weather charts.
"When computers came in, forecasting became much more of a science,"
McPherson added. "It started, literally, a revolution in forecasting."
George Parmley Cressman was born Oct. 7, 1919, in West Chester, Pa.
He and a boyhood friend, who also became a meteorologist, took an
early interest in weather to determine when snowstorms would provide
good opportunities for sledding.
After graduating from Pennsylvania State University, Dr. Cressman
studied meteorology in a military course at New York University, then
served as a forecaster with the Army Air Forces. In January 1943, he
began teaching meteorology to military students at the University of
Chicago, where he became a protege of Carl-Gustaf Rossby, a renowned
meteorologist who identified the jet stream.
Dr. Cressman manned such distant outposts of the U.S. Weather Bureau
as Lewistown, Mont., Homestead, Fla., and Mount Home, Idaho, before
receiving his doctorate from the University of Chicago in 1949. He then
worked at the Air Force's central weather command at Andrews Air
Force Base, seeking ways to improve the scientific validity of weather
predictions. In the early 1950s, he compiled forecasts for atomic bomb
tests in the Nevada desert.
In 1955, one year after Dr. Cressman began to concentrate on applying
computers to meteorology, the Weather Bureau (renamed the National
Weather Service in 1967) was issuing its first computer-generated
forecasts. The "Cressman Analysis" or "Cressman Method," as it
became known, greatly refined forecasting methods and gave rise to
what meteorologists call "numerical weather prediction."
"That is an achievement that, I think, 100 years from now he'll still be
known for," Hallgren said.
In the early 1960s, when Dr. Cressman was director of the National
Meteorological Center, which was the government's joint military and
civilian forecasting unit at the time, he instigated efforts to share weather
data with the Soviet Union. He continued to expand the use of
computers in weather forecasting throughout the 1960s.
As director of the Weather Service, Dr. Cressman added 100 weather
radars to the national network in the 1970s and established dozens of
Weather Service branches to provide accurate local forecasts across the
country. He stepped down in 1979 but continued to work as a consultant
to weather services in China, Spain and Brazil for several years.
He was president of the American Meteorological Society and received
the International Meteorological Organization Prize -- the highest honor
in his field -- in 1978. He conducted research on gravity waves and other
climatic phenomena until the late 1980s.
Dr. Cressman lived in District Heights before moving to Rockville in
1964. He was a skilled photographer, won awards in archery, enjoyed
mountain hiking with his family and was a member of the Cosmos Club.
He also enjoyed classical music, and throughout the 1950s was organist
at the old Bethlehem Lutheran Church in Southeast Washington.
His first wife of 32 years, Nelia Hazard Cressman, died in 1974.
Survivors include his wife of 32 years, Frances Cressman, of North
Bethesda; four children from his first marriage, Ruth Boyd of
Kealakekua, Hawaii, George I. Cressman of Manchester, Mo., Catherine
Beck of Grove City, Pa., and Florence Gardner of Mooresville, N.C.; a
brother; nine grandchildren; and 10 great-grandchildren.
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