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The Third Northeast Regional Operational Workshop, focusing on hydrometeorology in the northeastern United States, was held 6–7 November 2001 in Albany, New York. Sessions covered cold season events, warm season events, modeling, and operational techniques. A summary of workshop presentations is provided.
The Third Northeast Regional Operational Workshop, focusing on hydrometeorology in the northeastern United States, was held 6–7 November 2001 in Albany, New York. Sessions covered cold season events, warm season events, modeling, and operational techniques. A summary of workshop presentations is provided.
The First Northeast Regional Operational Workshop, focusing on hydrometeorology in the northeastern United States, was held 21–23 September 1999 in Albany, New York. Sessions in local and mesoscale modeling, lake-effect snow, hydrology, heavy precipitation forecasting and events, operational techniques, and northeast severe convection were presented. A summary of workshop presentations is provided.
The First Northeast Regional Operational Workshop, focusing on hydrometeorology in the northeastern United States, was held 21–23 September 1999 in Albany, New York. Sessions in local and mesoscale modeling, lake-effect snow, hydrology, heavy precipitation forecasting and events, operational techniques, and northeast severe convection were presented. A summary of workshop presentations is provided.
Abstract
Analyses and predictions of explosive cyclogenesis over the western North Atlantic Ocean during the 1987/88 cold season were compared. The analyses were the manual and automated series produced at the National Meteorological Center (NMC). The forecasts were those produced by the nested grid model (NGM) and the “aviation run” of the global spectral model (AVN) at NMC, and also by a simple checklist employed by the National Weather Service (NWS) Forecast Office, Boston.
Skill of the forecast has evidently improved since the preceding year. Probability of detection of an event in a specified 24-h period, with the manual analyses used as verification, approached 72% for the NGM in the range of 0–24 h with a false alarm rate of 17%. In the range of 36–60 h, the values for the AVN forecasts were 42% and 30%. When the automated analyses were used for verification, forecast performance was somewhat better.
The accuracy of the checklist forecasts was comparable to that of the AVN forecasts but not as good as that of the NGM predictions, in the small sample available for comparison.
Deepening in the NGM forecasts over the range of 12–24 h was 2 mb less than in the manual analyses, with a correlation of 0.55. The accuracy was limited mainly by errors in timing, with the model failing to well represent the initial analyzed deepening but catching up later. The automated analyses displayed a similar failure, with a correlation of 0.49 between analyses. Uncertainty in initial analysis is a major factor limiting present accuracy, especially at short range.
Abstract
Analyses and predictions of explosive cyclogenesis over the western North Atlantic Ocean during the 1987/88 cold season were compared. The analyses were the manual and automated series produced at the National Meteorological Center (NMC). The forecasts were those produced by the nested grid model (NGM) and the “aviation run” of the global spectral model (AVN) at NMC, and also by a simple checklist employed by the National Weather Service (NWS) Forecast Office, Boston.
Skill of the forecast has evidently improved since the preceding year. Probability of detection of an event in a specified 24-h period, with the manual analyses used as verification, approached 72% for the NGM in the range of 0–24 h with a false alarm rate of 17%. In the range of 36–60 h, the values for the AVN forecasts were 42% and 30%. When the automated analyses were used for verification, forecast performance was somewhat better.
The accuracy of the checklist forecasts was comparable to that of the AVN forecasts but not as good as that of the NGM predictions, in the small sample available for comparison.
Deepening in the NGM forecasts over the range of 12–24 h was 2 mb less than in the manual analyses, with a correlation of 0.55. The accuracy was limited mainly by errors in timing, with the model failing to well represent the initial analyzed deepening but catching up later. The automated analyses displayed a similar failure, with a correlation of 0.49 between analyses. Uncertainty in initial analysis is a major factor limiting present accuracy, especially at short range.
The modernization of the National Weather Service (NWS) will provide new datasets along with advanced technological capabilities that will enhance our understanding of meteorological and hydrological processes. Improved local warning and forecast techniques should flow from this new understanding. The knowledge transfer to improved services can be greatly accelerated by local partnerships with universities and others in the scientific community. Hence, a key objective of the modernization and associated restructuring of the NWS is to stimulate collaborative research activities among weather forecast offices, river forecast centers, universities, and others in the scientific community. This article describes steps the NWS is taking to improve opportunities for collaboration.
The modernization of the National Weather Service (NWS) will provide new datasets along with advanced technological capabilities that will enhance our understanding of meteorological and hydrological processes. Improved local warning and forecast techniques should flow from this new understanding. The knowledge transfer to improved services can be greatly accelerated by local partnerships with universities and others in the scientific community. Hence, a key objective of the modernization and associated restructuring of the NWS is to stimulate collaborative research activities among weather forecast offices, river forecast centers, universities, and others in the scientific community. This article describes steps the NWS is taking to improve opportunities for collaboration.
Abstract
The complex combination of synoptic and mesoscale interactions, topographic influences, and large population densities poses a multitude of challenging problems to winter weather forecasters throughout the eastern United States. Over the years, much has been learned about the structure, evolution, and attendant precipitation within winter storms. As a result, numerous operational procedures, forecast applications, and objective techniques have been developed at National Weather Service offices to assess the potential for, and forecast, hazardous winter weather. A companion paper by Maglaras et al. provided an overview of the challenge of forecasting winter weather in the eastern United States.
This paper focuses on the problem of cyclogenesis from an operational perspective. Since pattern recognition is an important tool employed by field forecasters, a review of several conceptual models of cyclogenesis often observed in the east is presented. These include classical Miller type A and B cyclogenesis, zipper lows, 500-mb cutoff lows, and cold-air cyclogenesis. The ability of operational dynamical models to predict East Coast cyclones and, in particular, explosive cyclogenesis is explored. An operational checklist that utilizes information from the Nested Grid Model to forecast the potential for rapid cyclogenesis is also described. A review of signatures related to cyclogenesis in visible, infrared, and water vapor satellite imagery is presented. Finally, a study of water vapor imagery for 16 cases of explosive cyclogenesis between 1988 and 1990 indicates that an acceleration of a dry (dark) surge with speeds exceeding 25 m s−1, toward a baroclinic zone, is an excellent indicator of the imminent onset of rapid deepening.
Abstract
The complex combination of synoptic and mesoscale interactions, topographic influences, and large population densities poses a multitude of challenging problems to winter weather forecasters throughout the eastern United States. Over the years, much has been learned about the structure, evolution, and attendant precipitation within winter storms. As a result, numerous operational procedures, forecast applications, and objective techniques have been developed at National Weather Service offices to assess the potential for, and forecast, hazardous winter weather. A companion paper by Maglaras et al. provided an overview of the challenge of forecasting winter weather in the eastern United States.
This paper focuses on the problem of cyclogenesis from an operational perspective. Since pattern recognition is an important tool employed by field forecasters, a review of several conceptual models of cyclogenesis often observed in the east is presented. These include classical Miller type A and B cyclogenesis, zipper lows, 500-mb cutoff lows, and cold-air cyclogenesis. The ability of operational dynamical models to predict East Coast cyclones and, in particular, explosive cyclogenesis is explored. An operational checklist that utilizes information from the Nested Grid Model to forecast the potential for rapid cyclogenesis is also described. A review of signatures related to cyclogenesis in visible, infrared, and water vapor satellite imagery is presented. Finally, a study of water vapor imagery for 16 cases of explosive cyclogenesis between 1988 and 1990 indicates that an acceleration of a dry (dark) surge with speeds exceeding 25 m s−1, toward a baroclinic zone, is an excellent indicator of the imminent onset of rapid deepening.
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