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; Charney and Shukla 1981 ; Xue and Shukla 1993 ; Clark and Arritt 1995 ; Clark et al. 2001 ). The surface boundary focus of the present Ethiopian study is SST. However, El Niño–Southern Oscillation (ENSO)-related “predictability barrier” in Northern Hemisphere spring (e.g., Goswami and Shukla 1991 ; Webster and Yang 1992 ; Webster et al. 1998 ) can pose a major challenge to providing seasonal rainfall forecasts two or more months in advance in the tropics ( Goddard et al. 2001 ; Korecha and
; Charney and Shukla 1981 ; Xue and Shukla 1993 ; Clark and Arritt 1995 ; Clark et al. 2001 ). The surface boundary focus of the present Ethiopian study is SST. However, El Niño–Southern Oscillation (ENSO)-related “predictability barrier” in Northern Hemisphere spring (e.g., Goswami and Shukla 1991 ; Webster and Yang 1992 ; Webster et al. 1998 ) can pose a major challenge to providing seasonal rainfall forecasts two or more months in advance in the tropics ( Goddard et al. 2001 ; Korecha and
Meteorology of Tropical West Africa: The Forecasters’ Handbook is set to change the way forecasters, researchers, and students learn about tropical meteorology and will serve to drive demand for new forecasting tools. Daily weather patterns directly influence human survival in Africa more so than in any other well-populated continent. Furthermore, West Africa currently exhibits one of the largest population growths on Earth, with many emerging megacities that are prone to urban flooding from
Meteorology of Tropical West Africa: The Forecasters’ Handbook is set to change the way forecasters, researchers, and students learn about tropical meteorology and will serve to drive demand for new forecasting tools. Daily weather patterns directly influence human survival in Africa more so than in any other well-populated continent. Furthermore, West Africa currently exhibits one of the largest population growths on Earth, with many emerging megacities that are prone to urban flooding from
NOAA’s African Desk, established in 1994, provides decision support services and contributes to the development of capacity in weather and climate forecasting through knowledge and technology transfer. Drought is one of the leading causes of death in Africa because of its impact on access to sanitary water and food. This challenge has mobilized the international community to develop famine early warning systems (FEWS) to bring safe food and water to populations in need. Over the past several
NOAA’s African Desk, established in 1994, provides decision support services and contributes to the development of capacity in weather and climate forecasting through knowledge and technology transfer. Drought is one of the leading causes of death in Africa because of its impact on access to sanitary water and food. This challenge has mobilized the international community to develop famine early warning systems (FEWS) to bring safe food and water to populations in need. Over the past several
A hydrological modeling framework suitable for multiscale flood forecasting is introduced and used to build capacity in the Republic of Namibia and around the world. Situated along Africa’s southwest coast, Namibia is a country renowned for its ancient deserts. The most arid country in sub-Saharan Africa, Namibia contains the majority of the Namib Desert, the oldest in the world, and a large portion of the dry Kalahari savannah and semidesert region ( Barnard et al. 1998 ). However, 15% of the
A hydrological modeling framework suitable for multiscale flood forecasting is introduced and used to build capacity in the Republic of Namibia and around the world. Situated along Africa’s southwest coast, Namibia is a country renowned for its ancient deserts. The most arid country in sub-Saharan Africa, Namibia contains the majority of the Namib Desert, the oldest in the world, and a large portion of the dry Kalahari savannah and semidesert region ( Barnard et al. 1998 ). However, 15% of the
short-term forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF), this study revealed positive biases in LLJ speed, negative biases in low-level cloud cover, and therefore a large overestimation of solar radiation during the day. The LLJ biases, which should also affect advection and turbulent mixing, are consistent with biases in the north–south pressure gradient due to the misrepresentation of convection in the Sahel ( Marsham et al. 2013 ). For the more recent CMIP5
short-term forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF), this study revealed positive biases in LLJ speed, negative biases in low-level cloud cover, and therefore a large overestimation of solar radiation during the day. The LLJ biases, which should also affect advection and turbulent mixing, are consistent with biases in the north–south pressure gradient due to the misrepresentation of convection in the Sahel ( Marsham et al. 2013 ). For the more recent CMIP5
-resolution simulations is attributed to the treatment of convection (explicit vs parameterized) and not directly to the resolution differences. With preliminary testing to select physical parameterizations that work well in the region, the regional Weather Research and Forecasting (WRF) Model ( Skamarock et al. 2008 ) accurately reproduces West African rainfall on seasonal to interannual time scales (e.g., Hagos and Cook 2007 ; Cook and Vizy 2012 ; Vizy et al. 2013 ; Crétat et al. 2014 ). Working on the synoptic
-resolution simulations is attributed to the treatment of convection (explicit vs parameterized) and not directly to the resolution differences. With preliminary testing to select physical parameterizations that work well in the region, the regional Weather Research and Forecasting (WRF) Model ( Skamarock et al. 2008 ) accurately reproduces West African rainfall on seasonal to interannual time scales (e.g., Hagos and Cook 2007 ; Cook and Vizy 2012 ; Vizy et al. 2013 ; Crétat et al. 2014 ). Working on the synoptic
60% of the Atlantic basin tropical storms and nonmajor hurricanes, and that they account for about 85% of major hurricanes ( Landsea 1993 ). However, the proportion that strengthens to tropical cyclones among those leaving the West Africa coast is quite small [about 6%, see Hopsch et al. (2010) and Arnault and Roux (2011) ]. Based on automatic tracking of vorticity centers in European Centre for Medium-Range Weather Forecasts (ECMWF) analyses, Thorncroft and Hodges (2001) developed a 20-yr
60% of the Atlantic basin tropical storms and nonmajor hurricanes, and that they account for about 85% of major hurricanes ( Landsea 1993 ). However, the proportion that strengthens to tropical cyclones among those leaving the West Africa coast is quite small [about 6%, see Hopsch et al. (2010) and Arnault and Roux (2011) ]. Based on automatic tracking of vorticity centers in European Centre for Medium-Range Weather Forecasts (ECMWF) analyses, Thorncroft and Hodges (2001) developed a 20-yr
fields on 3-hourly intervals over West Africa. To reduce the uncertainty of using reanalysis data, other global reanalyses are also compared with MERRA, including the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR; Saha et al. 2010 ), the ECMWF interim reanalysis (ERA-Interim; Dee et al. 2011 ), and the ECMWF reanalysis from their operational forecasts for the AMMA observational campaign with AMMA radiosonde data assimilated (ECMWF-OPERA; Agustí
fields on 3-hourly intervals over West Africa. To reduce the uncertainty of using reanalysis data, other global reanalyses are also compared with MERRA, including the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR; Saha et al. 2010 ), the ECMWF interim reanalysis (ERA-Interim; Dee et al. 2011 ), and the ECMWF reanalysis from their operational forecasts for the AMMA observational campaign with AMMA radiosonde data assimilated (ECMWF-OPERA; Agustí
performed better in humid regions than in arid regions and overestimated light rainfall while underestimating moderate and heavy rainfall. Reanalyses combine model forecast with observations to provide globally continuous fields of the analyzed observations and other variables derived from the background model. While observationally driven, their ability to estimate physical processes, such as precipitation, depends on many factors, including observational coverage and model performance, and is
performed better in humid regions than in arid regions and overestimated light rainfall while underestimating moderate and heavy rainfall. Reanalyses combine model forecast with observations to provide globally continuous fields of the analyzed observations and other variables derived from the background model. While observationally driven, their ability to estimate physical processes, such as precipitation, depends on many factors, including observational coverage and model performance, and is
-Saharan drought did not appear in conjunction with unusually dry southerly surface air from the tropical Atlantic. Lamb (1983) also found that during the extremely dry year, the northward moisture flux across the Gulf of Guinea was shallow compared with the much deeper monsoon layer, during the less severe drought years. Cadet and Nnoli (1987) used one summer (1979) of the European Centre for Medium-Range Weather Forecasts (ECMWF) data to study the water vapor transport over Africa. They analyzed biweekly
-Saharan drought did not appear in conjunction with unusually dry southerly surface air from the tropical Atlantic. Lamb (1983) also found that during the extremely dry year, the northward moisture flux across the Gulf of Guinea was shallow compared with the much deeper monsoon layer, during the less severe drought years. Cadet and Nnoli (1987) used one summer (1979) of the European Centre for Medium-Range Weather Forecasts (ECMWF) data to study the water vapor transport over Africa. They analyzed biweekly
