Abstract Private sector meteorology is a rapidly growing enterprise. It has been estimated that the provision of weather information has, by some estimates, a global market totaling in the billions of dollars. Further, the decisions based on such information could easily total trillions of dollars in the U.S. economy alone. The private sector clearly plays an important, and growing, role at the interface of weather research and the weather information needs of society. To date, little information has been paid to the connections of the meteorological research community and the scientific needs of the private sector. Thus, the time is ripe to stimulate a more active dialogue between what is generally considered the “basic” research community of physical and social scientists and those individuals and businesses that provide weather information to myriad customers across the U.S. economy. In December 2000, the U.S. Weather Research Program (supported by NSF, NOAA, NASA, and the U.S. Navy) sponsored a worksh...

Improved performance photodetectors are required for a variety of applications in Biomedical, Astronomy and High-Energy Physics research. The combination of high Quantum efficiencies, III–V photocathodes and Avalanche PhotoDiodes (APDs) can provide enhancements applicable to these research areas. This is particularly true in the photon counting regime. Preliminary development of a Winston-cone-based Hybrid device (ReFerence) and an APD-based imaging Hybrid Photomultiplier Tube are presented. These devices take advantage of the high-performance cathodes and mechanically robust structures used in state of the art night vision imagining systems. Theoretical and observed performance are described.

A significant number of tropical cyclones move into the midlatitudes and transform into extratropical cyclones. This process is generally referred to as extratropical transition ( ET). During ET a cyclone frequently produces intense rainfall and strong winds and has increased forward motion, so that such systems pose a serious threat to land and maritime activities. Changes in the structure of a system as it evolves from a tropical to an extratropical cyclone during ET necessitate changes in forecast strategies. In this paper a brief climatology of ET is given and the challenges associated with forecasting extratropical transition are described in terms of the forecast variables ( track, intensity, surface winds, precipitation) and their impacts ( flooding, bush fires, ocean response). The problems associated with the numerical prediction of ET are discussed. A comprehensive review of the current understanding of the processes involved in ET is presented. Classifications of extratropical transition are described and potential vorticity thinking is presented as an aid to understanding ET. Further sections discuss the interaction between a tropical cyclone and the midlatitude environment, the role of latent heat release, convection and the underlying surface in ET, the structural changes due to frontogenesis, the mechanisms responsible for precipitation, and the energy budget during ET. Finally, a summary of the future directions for research into ET is given.

Summer severe weather (SSW) can strike suddenly and unexpectedly with disastrous consequences for human activity. Considerable progress has been made in the past ten years in the operational forecasting of SSW. Traditionally, SSW was defined to consist of tornadoes, strong winds, hail, lightning and heavy rain. Hazardous types of strong winds have recently been expanded to include microbursts, macrobursts and surfacing rear inflow jet damage behind mesoscale convective systems. Doppler radar was used to relate surface damage to the appropriate atmospheric phenomena, first diagnostically and then prognostically. This improvement in classification has fedback to and improved the forecast process. Concurrent progress has been made in the use of synoptic observations. The concept of helical wind profiles and improved knowledge of the role of dry mid-level air has improved the forecasting of tornadoes and strong gusty winds. Moisture pur convergence, derived from surface measurements, shows great promise in identifying areas of storm initiation. Satellite imagery has been used to identify dynamical atmospheric boundaries. Numerical modelling of the interaction of environmental wind profiles and individual thunderstorms has greatly contributed to the understanding of SSW. Studies of spatial and temporal patterns of lightning both specific cases and climatology, contribute to the forecasting of severe storms. Polarization radar results have shown progress in separating the signals of hail from those of rain and in the improved measurement of heavy rainfalls. Radar observation of clear air boundaries curd their interactions show potential for the forecasting of thunderstorm initiation. Though not traditionally considered part of SSW, hurricanes that evolve into extra-tropical storms share many of the same hazardous features. The progress in computing, communications and display technologies has also made substantial contributions to operational forecasting and to the dissemination of weather warnings.