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motion, geopotential height, satellite outgoing longwave radiation (OLR), and winds. As the analysis is focused on baroclinic flood events in the satellite era, it is believed that the NCEP–NCAR data will provide an adequate description of the large-scale meteorological forcing ( Carter and Elsner 1997 ). In addition to the composite analysis, we investigate the predictability of flood events by considering climate and weather model data at lead times from days to weeks, and we study three
motion, geopotential height, satellite outgoing longwave radiation (OLR), and winds. As the analysis is focused on baroclinic flood events in the satellite era, it is believed that the NCEP–NCAR data will provide an adequate description of the large-scale meteorological forcing ( Carter and Elsner 1997 ). In addition to the composite analysis, we investigate the predictability of flood events by considering climate and weather model data at lead times from days to weeks, and we study three
1. Introduction The purpose of this study is to investigate the characteristics of afternoon thunderstorms on the island of Taiwan during the warm season (May–October 2005–2008) for days when synoptic forcing was weak. It is particularly challenging to forecast thunderstorms in Taiwan, which is a mountainous island characterized by the Central Mountain Range (CMR) running across most of it in a north-northeast–south-southwest orientation at an average height of about 2 km ( Fig. 1 ). Mountains
1. Introduction The purpose of this study is to investigate the characteristics of afternoon thunderstorms on the island of Taiwan during the warm season (May–October 2005–2008) for days when synoptic forcing was weak. It is particularly challenging to forecast thunderstorms in Taiwan, which is a mountainous island characterized by the Central Mountain Range (CMR) running across most of it in a north-northeast–south-southwest orientation at an average height of about 2 km ( Fig. 1 ). Mountains
JUNE1988 KENNETH F. HEIDEMAN AND J. MICHAEL FRITSCH 115Forcing Mechanisms and Other Characteristics of Significant Summertime Precipitation KENNETH F. HEIDEMANNOAA /ERL /PROFS, Boulder, Colorado J. MICHAEL FRITSCHDepartment of Meteorology, The Pennsylvania State University, University Park, Pennsylvania(Manuscript received 2 November 1987, in final form 29 February 1988
JUNE1988 KENNETH F. HEIDEMAN AND J. MICHAEL FRITSCH 115Forcing Mechanisms and Other Characteristics of Significant Summertime Precipitation KENNETH F. HEIDEMANNOAA /ERL /PROFS, Boulder, Colorado J. MICHAEL FRITSCHDepartment of Meteorology, The Pennsylvania State University, University Park, Pennsylvania(Manuscript received 2 November 1987, in final form 29 February 1988
288 WEATHER AND FORECASTING VOLUME7A Description of the Air Force Real-Time Nephana~ysfis Model THOMAS M. HAMILL*Meteorological Models Section. Air Force Global Weather Central, Offutt AFB, Nebraska ROBERT P. D'ENTREMONT AND JAMES T. BUNTINGSatellite Meteorology Branch, Geophysics Directorate, Phillips Laboratory, Hanscorn AFB. Massachusetts(Manuscript received 24
288 WEATHER AND FORECASTING VOLUME7A Description of the Air Force Real-Time Nephana~ysfis Model THOMAS M. HAMILL*Meteorological Models Section. Air Force Global Weather Central, Offutt AFB, Nebraska ROBERT P. D'ENTREMONT AND JAMES T. BUNTINGSatellite Meteorology Branch, Geophysics Directorate, Phillips Laboratory, Hanscorn AFB. Massachusetts(Manuscript received 24
−1 ) or gale force, damaging, and hurricane force winds in quadrants surrounding the TC. These are collectively referred to as wind radii. NHC forecasts hurricane force wind radii through 36 hours, and damaging and gale force wind radii through 72 hours, while intensity and track are forecast through 120 hours. The forecasting of TC structure/wind radii at NHC was last described in the refereed literature by Rappaport et al. (2009) . An update to that information is provided here. The 34-kt wind
−1 ) or gale force, damaging, and hurricane force winds in quadrants surrounding the TC. These are collectively referred to as wind radii. NHC forecasts hurricane force wind radii through 36 hours, and damaging and gale force wind radii through 72 hours, while intensity and track are forecast through 120 hours. The forecasting of TC structure/wind radii at NHC was last described in the refereed literature by Rappaport et al. (2009) . An update to that information is provided here. The 34-kt wind
( Gallus 1999 ) or soil moisture ( Gallus and Segal 2000 ). In addition, other mesoscale features possibly acting as the main source for convective forcing (such as outflow boundaries) are poorly resolved in the models ( Kain and Fritsch 1993 ; Stensrud and Fritsch 1994 ). The dominance of convective system rainfall and the importance of smaller-scale forcing mechanisms in the warm season result in precipitation skill scores remaining much lower in the warm season than in the cold season (e.g., Olson
( Gallus 1999 ) or soil moisture ( Gallus and Segal 2000 ). In addition, other mesoscale features possibly acting as the main source for convective forcing (such as outflow boundaries) are poorly resolved in the models ( Kain and Fritsch 1993 ; Stensrud and Fritsch 1994 ). The dominance of convective system rainfall and the importance of smaller-scale forcing mechanisms in the warm season result in precipitation skill scores remaining much lower in the warm season than in the cold season (e.g., Olson
—for the experiments presented in this study—is running at a horizontal resolution of 18 km with 37 levels. The integration domain covers Europe and large parts of the North Atlantic ( Fig. 1 ), and the maximum forecast range is 54 h. While ALADIN-LAEF is in operational mode, a breeding–blending technique is used to generate the initial perturbations ( Wang et al. 2011 ); in this study the downscaling configuration (of ECMWF-EPS or GEFS) is used to clearly separate the effects of forcing the regional
—for the experiments presented in this study—is running at a horizontal resolution of 18 km with 37 levels. The integration domain covers Europe and large parts of the North Atlantic ( Fig. 1 ), and the maximum forecast range is 54 h. While ALADIN-LAEF is in operational mode, a breeding–blending technique is used to generate the initial perturbations ( Wang et al. 2011 ); in this study the downscaling configuration (of ECMWF-EPS or GEFS) is used to clearly separate the effects of forcing the regional
membership (84 members for every 24-h cycle), all providing an improved sampling of forecast uncertainty. Fig . 1. Average anomaly correlation by lead day for 500-hPa geopotential heights over the NH covering the period of 1 Sep 2013–28 Feb 2014 for the deterministic GFS (blue) and the GEFS ensemble mean (red). In this study, the operational GEFS v11 configuration is extended to 35 days, and the forecast skill is evaluated ( Melhauser et al. 2016 ). Various SST forcing experiments are performed to
membership (84 members for every 24-h cycle), all providing an improved sampling of forecast uncertainty. Fig . 1. Average anomaly correlation by lead day for 500-hPa geopotential heights over the NH covering the period of 1 Sep 2013–28 Feb 2014 for the deterministic GFS (blue) and the GEFS ensemble mean (red). In this study, the operational GEFS v11 configuration is extended to 35 days, and the forecast skill is evaluated ( Melhauser et al. 2016 ). Various SST forcing experiments are performed to
1. Introduction Extratropical cyclones producing extreme surface wind conditions are ubiquitous over the oceans during winter. Winds with speeds in excess of 20 m s −1 are observed more than 10% of the time within broad swaths of the storm tracks located over the western and central North Pacific, and over the North Atlantic to the north of 30°N ( Sampe and Xie 2007 ). The number of storms producing hurricane force (HF) winds (speeds greater than 32.9 m s −1 ) is generally greater than 20 per
1. Introduction Extratropical cyclones producing extreme surface wind conditions are ubiquitous over the oceans during winter. Winds with speeds in excess of 20 m s −1 are observed more than 10% of the time within broad swaths of the storm tracks located over the western and central North Pacific, and over the North Atlantic to the north of 30°N ( Sampe and Xie 2007 ). The number of storms producing hurricane force (HF) winds (speeds greater than 32.9 m s −1 ) is generally greater than 20 per
uncertainties. Such an approach has the ability to filter unpredictable stochastic processes and capture more realistic ENSO evolutions ( Zheng et al. 2009a ). But there are still large systematic biases since the Markov stochastic model perturbation cannot approximate the effect of all model errors to the greatest extent ( Qi et al. 2017 ). Therefore, an optimal method was suggested to represent the combined effect of different kinds of model errors. Duan and Zhou (2013) extended the (linear) forcing
uncertainties. Such an approach has the ability to filter unpredictable stochastic processes and capture more realistic ENSO evolutions ( Zheng et al. 2009a ). But there are still large systematic biases since the Markov stochastic model perturbation cannot approximate the effect of all model errors to the greatest extent ( Qi et al. 2017 ). Therefore, an optimal method was suggested to represent the combined effect of different kinds of model errors. Duan and Zhou (2013) extended the (linear) forcing
