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George Cressman (1919–2008)

Basic Facts

  • Full name: George Parmley Cressman
  • Born: 7 October 1919, West Chester, Pennsylvania, USA
  • Died: 17 April 2008 (age 88), Rockville, Maryland, USA
  • Cause of death: Alzheimer’s disease

Education

Year Degree / Institution Notes
– B.S., Pennsylvania State University Introduced to meteorology by Helmut Landsberg and Hans Neuburger, both refugees from Nazi Germany
WWII Military meteorology course, New York University  
1949 Doctorate, University of Chicago Studied under Carl-Gustaf Rossby

Career

  • WWII: Served as a military meteorologist with the United States Army Air Forces.
  • Post-WWII: Taught meteorology at the University of Chicago (under Rossby’s program).
  • 1950s: Worked on weather predictions for atomic bomb tests in Nevada.
  • 1954–1964: First director of the Joint Numerical Weather Prediction Unit (JNWPU) / National Meteorological Center. Led the effort to bring numerical weather prediction into routine operational use.
  • 1965–1979: Chief of the Weather Bureau (later Director of the National Weather Service after NOAA’s creation in 1970). Oversaw the transition to the National Weather Service and expanded weather radar networks nationwide.
  • Post-retirement: Consulted for weather services in China, Spain, and Brazil.

Major Scientific Contributions

Joint Numerical Weather Prediction Unit (JNWPU)

The JNWPU was established on 1 July 1954 as a joint effort of the Weather Bureau, the Air Weather Service, and the Navy Aerological Service. Cressman was chosen as its first director. Working with colleagues from all three services, he led the task of making numerical weather prediction operationally reliable – bridging the gap between the research demonstrations of the early 1950s and routine daily forecasting.

Cressman Objective Analysis (1959)

Cressman’s most enduring scientific contribution was his method of “objective analysis” – the systematic procedure for transferring irregularly spaced weather observations to regularly spaced grid points suitable for numerical computation. Published as “An Operational Objective Analysis System” in Monthly Weather Review (1959), the technique was based on ideas originally developed by Pall Bergthorsson and Bo Doos (1955) in Sweden.

The Cressman method is a successive correction technique: it starts with a “first guess” field (typically a previous forecast) and iteratively adjusts it toward observed values using a distance-weighted influence function with decreasing scan radii. This approach was the precursor to modern data assimilation methods (optimal interpolation, variational methods) that are essential to every operational NWP system today.

Operational NWP Pioneer

Cressman applied computers to meteorology and, as one obituary stated, “helped to change weather forecasting into a codified science.” He developed the first program to accurately and reliably produce routine computer-based weather forecasts.

National Weather Service Leadership

As head of the Weather Bureau / National Weather Service (1965–1979), Cressman:

  • Oversaw the expansion of weather radar networks across the United States
  • Supervised the organizational transition from the Weather Bureau to the National Weather Service under the newly created NOAA (1970)
  • Advocated for sharing weather data with the Soviet Union in the early 1960s, during the Cold War

Awards and Honors

  • International Meteorological Organization Prize (1977)
  • President of the American Meteorological Society (1978)

Connections to Other Scientists

  • Carl-Gustaf Rossby: Doctoral advisor at the University of Chicago.
  • Helmut Landsberg and Hans Neuburger: Introduced him to meteorology at Penn State.
  • Jule Charney: Cressman’s JNWPU implemented Charney’s theoretical advances operationally.
  • Pall Bergthorsson and Bo Doos: Their 1955 successive correction analysis method was the basis for Cressman’s operational scheme.
  • Philip Thompson: Colleague in early NWP development.

Key Publications

  • Cressman, G. P. (1959). “An Operational Objective Analysis System.” Monthly Weather Review, 87(10), 367–374.

Sources

Accessed: 2026-04-02