Roy Rasmussen, Ben Bernstein, and Greg Stossmeister. Co-nominees and co-authors included Masataka Murakami (Meteorological Research Institute, Tsukuba, Japan), Jon Reisner (Los Alamos National Laboratory) and Boba Stankov (NOAA).

Shallow upslope storms, which develop along the Front Range two to six times per year and last from three to four days each, are of great interest to atmospheric scientists as well as to pilots. The storms' relatively warm cloud tops allow droplets to remain unfrozen for long periods, posing a significant aviation hazard. This study examines a 1990 storm in detail, showing the dynamical and microphysical mechanisms that led to long-lived regions of supercooled liquid water and freezing drizzle aloft. These mechanisms include upper-level jet streaks, which can help suppress vertical development of the precipitation, and sequential surges of cold air, which at first hasten but eventually diminish the production of supercooled liquid water. Insights from this and later work have led to improved pilot training, better algorithms of in-flight icing, and improved paramaterization of supercooled liquid water in mesoscale models.

James Wilson and Daniel Megenhardt 

Using 32 days of data from the Convection and Precipitation/Electrification (CaPE) field project in Florida, this paper shows how the area's longer-lived multicellular storms - those more likely to cause serious damage - are sustained. Analysis shows that the formation and duration of these storms is related to the vertical wind shear and storm motion relative to two recurring boundaries, the East Coast Sea Breeze Front and the West Coast Front. By calculating the boundary-relative cell motion, forecasters can use these findings to improve storm forecasts, including those issued by automated systems. This represents a fundamental advance in short-term storm forecasting, with the findings already being applied in New Mexico, Alabama, Virginia, and Australia.

Roy Rasmussen, Jothiram Vivekanandan, and Jeff Cole. Co-authors included: M. Kuperman (United Airlines, San Francisco, CA), Barry Myers (Transport Canada, Montreal, Quebec), and Charles Masters (FAA, Atlantic City, NJ). 

A combination of five years of fundamental research and practical application went into these papers, which analyze a series of aircraft accidents that involved inadequate deicing. The authors found that the standard relationship between snowfall intensity and visibility that is used by many weather services can be misleading because of variations in snow type and differences in how visibility is affected by snowfall during the day versus the night. Because of this work, airlines have improved the procedures they use to estimate snowfall rates.

Juanzhen Jenny Sun (RAL/MMM) and N. Andrew Crook (RAL/MMM) 

The papers make an important contribution to atmospheric science by presenting a new method for improving 0-12 hour forecasts and, in so doing, advancing the scientific understanding of convection. They also break new ground in assimilating Doppler radar data into a cloud-scale model, providing the potential for significantly improving initial conditions in the model.

Larry Cornman, Corinne Morse, and Kent Goodrich (RAP). Co-nominee included Stephen Cohn (ATD now EOL). Co-authors included Warner Ecklund (Boulder, CO), Stephen Cohn (ATD now EOL), Eli Karplus (NCAR), Steven W. Mueller (RAP), and R. Andrew Weekley (RAP).

The papers describe new analysis techniques that represent a groundbreaking step in solving radar data quality problems.

These papers describe a new technique for retrieval of cloud microphysical parameters from dual-polarization radar measurements. The knowledge gained about cloud microphysical properties will allow development of improved parameterizations in operational and research weather prediction and climate models. Basic knowledge of cloud microphysical properties will also be enhanced, and it will be possible to better calculate the propagation characteristics of microwaves.

Bob Sharman (AAP/RAL). Co-nominees and co-authors included Todd Lane (ASP/CMS), Terry Clark (MMM/CSM), and Hsiao-Ming Hsu (MMM)

The article addresses two fundamental issues in atmospheric science that can affect aviation: the processes underlying the generation of gravity waves by cumulus convection (which can induce strong turbulence close to the tops of clouds), and the effect of lower-stratospheric gravity wave breaking on mixing and stratosphere-troposphere exchange. The work that builds on this research will help the Federal Aviation Administration develop new safety guidelines for specifying the distance between aircraft and the tops of convective clouds.

Janice Coen (RAL and MMM). Co-nominees and co-authors included Shankar Mahalingam (University of California, Riverside) and John Daily (University of Colorado, Boulder).

This paper represents an important contribution to our knowledge of wildfire dynamics and the coupling of fires with the surrounding atmosphere, and it presents fundamentally new observations that will change the focus and direction of future theoretical and modeling studies.

Rita Roberts. Co-nominee and co-author included Steven Rutledge (Colorado State University)

This paper outlines the incorporation of operational radar data into an automated nowcasting system for consistent and reliable improvement in short-term forecasts of thunderstorm behavior. The technique is now being incorporated in the production of National Weather Service warnings and in research at NOAA, NASA, and the Federal Aviation Administration.