50 th Anniversary of Operational Numerical Weather Prediction

1. 50th Anniversaryof Operational NumericalWeather Prediction John Jones Deputy Assistant Administrator for Weather ServicesJune 15, 2004 University of MarylandCollege Park

2. Overview • Forecasting 60 years ago: before Numerical Weather Prediction • Forecasting today: Model-based • Remaining challenges for the future • Debt to the Joint Numerical Weather Prediction Unit

3. Weather Prediction – 60 Years Ago June 15, 1944 • Forecasting was a subjective art • Based on surface observations • Forecasts of extreme events were poor beyond 12 hours

4. Limits of Predictability of Public Weather Forecasts (from Cressman 1970) Even as late as the early 70’s, forecast skill for snowstorms and hurricane force winds was only 12 hours

5. Revolution in Forecasting after World War II • Expanding Raob network • Improved theoretical basis • Development of computers All came together for: • Development of Numerical Weather Prediction models • Creation of the Joint Numerical Weather Prediction Unit in 1954

6. Forecasting Today Commissioned/Operational IBM Supercomputer in Gaithersburg, MD (June 6, 2003) • Based on sophisticated global and regional numerical models • Initialized with global observations, satellites, raobs, aircraft, ships, buoys, radar • Which produce accurate forecasts of extreme events 5-7 days in advance • Including “hazards assessment” product to day 14

7. Measuring Progress • Improved short range QPF • Fine scale is being improved

8. Measuring Progress • Increasing skill through day 7 • Predictions extended with improved skill

9. Major Advancement in Prediction: Extreme Events Captured 4-7 Days Ahead • Severe Weather – May 3-5, 2003 Outbreaks predicted 3+ days in advance • Snowstorms – Feb 17-19, 2003 predicted 5 days in advance • Hurricanes – Isabel, September 6-19, 2003, landfall predicted with record skill 5 days in advance

10. Cressman Chart for 2000 Today’s Weather 6 day s Gale-Force 4 day s Winds Of Hurricanes Severe Weather Outbreaks 2 day s 1 day Hurricane-Force Winds Time 12 hour s Heavy Snow Hurricanes 6 hour s Thunderstorms Heavy Snow 1 hour 10000 Km 1 Km 1000 Km 100 Km 10 Km Distance

11. Hurricane Isabel Thursday, 9/18/03 12 PM EDT 3-day forecast 5-day forecast

12. National Hurricane Center Atlantic Track Forecast Errors 500 1964-1973 400 1974-1983 1984-1993 300 Error (nautical miles) 1994-2002 200 2003 Isabel 100 0 72 12 24 36 48 96 120 Forecast Period (hours)

13. Remaining Challenges for the Future • As we approach the NPOESS era (2012), apply global satellite data to weather, climate, ocean and ecosystem prediction • Extend forecasts to Day 14 • Apply ensemble-based approach to quantify forecast uncertainties • We look forward to working with the international community to develop and implement “super ensemble” systems

14. Our Debt to the JNWPU • All these achievements were made possible by the creation of the JNWPU • The meteorological community owes much to the original members of the Air Force, Weather Bureau and the Navy who pushed for the creation of the JNWPU • They had the guts and foresight to get the best minds working on a challenging problem • Transformed weather prediction from a subjective “art” to a mathematically-based applied science • This transformation represents one of the great intellectual achievements of the 20th Century