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Carl W. Kreitzberg

This paper outlines a mesoscale forecast system that could be implemented within a few years in spite of relatively sparse direct observations. Methods are discussed of using satellite information on large mesoscale features to initiate numerical models. The models develop further mesoscale structures through the influence of mesoscale geographic features and organized convective systems. The output of the numerical model serves as the physical foundation upon which the latest detailed satellite data can be interpreted.

Although many of the techniques described are not off-the-shelf items today, they are entirely feasible. It is important that the components of the forecast system be developed in parallel, rather than in series, if the system is to be completed within five years. The components include: polar-orbiting satellites for high latitudes; geosynchronous satellites for low latitudes; a mesoclimatological data base largely from satellite data; a mesoscale numerical prediction model with lateral boundary data supplied from a conventional large-scale model; and a variety of simple models and empirical schemes for treating special mesoscale phenomena.

A review of current activities in mesometeorology provides substantial evidence that the revolution in large-scale weather prediction in the past decade will be followed by a similar revolution on the mesoscale in the next five years.

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Carl W. Kreitzberg

Effective reasoning, analysis and communication regarding natural phenomena require the use of models to render tractable the complexities of nature. This paper attempts to put into perspective the proper roles of different types of models to maximize the effectiveness of their utilization. The advances in short term forecasting envisioned for the 1970's from full implementation of new knowledge, models and technology will materialize only if the managers and researchers join in an interagency effort to provide the operational meteorologists with the education, techniques, tools and, particularly, the challenging working environment needed to fully develop man's role in forecasting. A program to meet these requirements is outlined.

The types of models discussed include: descriptive or synoptic, dynamic or analytic, numerical or physical, statistical or optimized. The uses of models discussed include: education (basic concepts), research (experimental), operations (customized). Since the operational meteorologist is responsible for the intelligent use of these types of models, he must continually update his training and properly understand the potential contributions of the models.

It is anticipated that during the 1970's routine computer models will become more refined and specialized data such as trajectories and probabilities will become more common. Highly specialized products will be available from special purpose models on a special request basis as field forecasters gain access to remote terminals. Also, forecasters will have access to specialized consultants when unusual events or unusual forecast requirements arise. Background materials will be provided to the applied meteorologists so that he may gain physical understanding from educational and research models including systematic numerical experiments. Communication advances will provide for dynamic (motion picture) displays of radar, synchronous satellite, weather map and weather forecast data.

Only if the operational forecasters do receive the necessary management and scientific support, will their jobs be challenging and attractive to highly motivated and qualified students; only then will the customers of specialized short term forecasts receive the benefits made feasible by science and technology.

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Ron Hadlock and Carl W. Kreitzberg

The Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) field study is designed to determine physical mechanisms and processes, and their critical spatial and temporal combinations, which can account for the wintertime phenomenon of explosively developing over-ocean atmospheric storms. Theoretical and numerical modeling research, during the five-year Office of Naval Research (ONR) Heavy Weather at Sea Accelerated Research Initiative ERICA program, comprises continuing effort, including the field study scheduled for 1 December 1988–28 February 1989. The ONR core field study is supplemented by the substantial participation of many other agencies and universities from the United States and Canada. Data will be obtained over the North Atlantic Ocean from Cape Hatteras to beyond Newfoundland, centered east of Cape Cod and south of Nova Scotia. The general timing and siting is chosen through consideration of historical storm occurrence data. Measurements in individual rapidly intensifying storms will be made from aircraft, buoys, and satellites, and by soundings and radars. Observations made during the pre-ERICA field test, January 1988, are discussed. This article describes the measurement objectives and the ways by which the field data will be collected.

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Donald J. Perkey, Kevin N. Young, and Carl W. Kreitzberg

Newspapers, television, and newsweeklies contained numerous articles proclaiming drought conditions during 1980 and 1981. This study investigates the causes and consequences of the drought as it affected eastern Pennsylvania. Precipitation data indicate below-average amounts during this period, while temperature records show above-average values. These values show that a meteorological drought did occur in this region during 1980 and 1981. However, meteorological factors were only part of the cause of the region's water shortage.

In addition to analyzing the drought's meteorological origin, this study probes the anthropogenic and regional social-political causes and impacts of the water shortage. Although regional water storage facilities are adequate when below-average precipitation amounts occur in very local areas, they are not adequate when below-average amounts occur over larger regions. This inadequacy is compounded when demands such as the needs of other political regions and the river-basin ecological system are included in addition to the primary region's industrial and domestic water requirements. Thus, this paper illustrates some of the complexities involved in trying to prepare for the normal fluctuations in a climatic variable such as precipitation amount.

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Richard Rotunno, Leonard J. Pietrafesa, John S. Allen, Bradley R. Colman, Clive M. Dorman, Carl W. Kreitzberg, Stephen J. Lord, Miles G. McPhee, George L. Mellor, Christopher N. K. Mooers, Pearn P. Niiler, Roger A. Pielke Sr., Mark D. Powell, David P. Rogers, James D. Smith, and Lian Xie

U.S. Weather Research Program (USWRP) prospectus development teams (PDTs) are small groups of scientists that are convened by the USWRP lead scientist on a one-time basis to discuss critical issues and to provide advice related to future directions of the program. PDTs are a principal source of information for the Science Advisory Committee, which is a standing committee charged with the duty of making recommendations to the Program Office based upon overall program objectives. PDT-1 focused on theoretical issues, and PDT-2 on observational issues; PDT-3 is the first of several to focus on more specialized topics. PDT-3 was convened to identify forecasting problems related to U.S. coastal weather and oceanic conditions, and to suggest likely solution strategies.

There were several overriding themes that emerged from the discussion. First, the lack of data in and over critical regions of the ocean, particularly in the atmospheric boundary layer, and the upper-ocean mixed layer were identified as major impediments to coastal weather prediction. Strategies for data collection and dissemination, as well as new instrument implementation, were discussed. Second, fundamental knowledge of air–sea fluxes and boundary layer structure in situations where there is significant mesoscale variability in the atmosphere and ocean is needed. Companion field studies and numerical prediction experiments were discussed. Third, research prognostic models suggest that future operational forecast models pertaining to coastal weather will be high resolution and site specific, and will properly treat effects of local coastal geography, orography, and ocean state. The view was expressed that the exploration of coupled air-sea models of the coastal zone would be a particularly fruitful area of research. PDT-3 felt that forecasts of land-impacting tropical cyclones, Great Lakes-affected weather, and coastal cyclogenesis, in particular, would benefit from such coordinated modeling and field efforts. Fourth, forecasting for Arctic coastal zones is limited by our understanding of how sea ice forms. The importance of understanding air-sea fluxes and boundary layers in the presence of ice formation was discussed. Finally, coastal flash flood forecasting via hydrologic models is limited by the present accuracy of measured and predicted precipitation and storm surge events. Strategies for better ways to improve the latter were discussed.

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