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provements in weather forecasts and warnings over the past several decades and is now poised to make even more spectacular advances. The main stumbling block to realizing significant progress in basic research and operational meteorology is the need for better measurements of the atmosphere, oceans, and land surface, and the need to better understand and delineate optimal combinations of measurement systems for specific forecast problems. Our nation has invested heavily in environmental satellites, and this investment has been paid back many times in improved understanding of the atmosphere and better warnings of hazards ranging from hurricanes to severe thunderstorms and tornadoes. However, observing systems of great importance, some of low cost, have been allowed to deteriorate. Examples include research Doppler radar facilities, global rawinsonde coverage, small research aircraft for boundary layer studies, and research surface mesonets. Meanwhile, the measurement of atmospheric water vapor continues to be vastly inadequate for a number of purposes, ranging from quantitative precipitation forecasting to climate prediction. In some cases, we have just begun to realize the potential benefits of certain types of measurements, such as soil moisture and the detailed structure of the tropopause. We must stand back and take a hard look at the costs and benefits of all existing and proposed measurement systems, from the perspective of basic scientific progress and societal need, with a blind eye toward the objectives and budgets of individual federal agencies.

If we elect to take a rational and well-thought-out approach toward observations in support of basic research and operational objectives, there is every reason to believe that the potential exists for great advances in understanding and prediction. A proper accounting of land surface physics and irreversible processes in the atmosphere may lead to large increases in the skill of seasonal forecasts. Better measurements of atmospheric water vapor and of cloud microphysical processes, particularly those involving ice, may allow us to solve a number of outstanding problems such as predicting the development and movement of mesoscale convective systems and the response of atmospheric water vapor and cloud cover to climate change. Advanced applications of ensemble and adjoint techniques to numerical weather prediction may reveal, in near real time, those parts of the atmosphere that are particularly susceptible to initial error, allowing us to target such regions for observational scrutiny and thereby greatly reduce numerical forecast errors. Better in situ observations in the atmospheric and oceanic environment of hurricanes may lead to dramatically improved forecasts of the motion and intensity of these great hazards. These are but examples of what we can expect to achieve in the coming decades if we take the right approach now.