Storm-Scale Numerical Rainfall Prediction for Five Precipitating Events over France: On the Importance of the Initial Humidity Field

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Abstract
This paper presents results of numerical experiments on five precipitating events: two cases of convective systems over the northern French plains that induced localized flooding, two cases of quasi-stationary systems over the southern French mountainous areas with recorded precipitation above 100 mm in less than 3–4 h, and the extreme flooding case of 12–13 November 1999 with daily precipitation having reached 550 mm, which led to more than 30 deaths. The ability of a high-resolution (2.5 km) model to forecast the quantitative precipitation associated with these five events is evaluated. Both qualitative evaluations that compare observed and modeled reflectivities or surface precipitation, and quantitative evaluations based on classical scores are performed to assess the quality of the numerical experiments. Starting from the same analysis as the operational models, the high-resolution model improves the results for one of the cases, the extreme flash flood case. For the four other cases, higher... Abstract This paper presents results of numerical experiments on five precipitating events: two cases of convective systems over the northern French plains that induced localized flooding, two cases of quasi-stationary systems over the southern French mountainous areas with recorded precipitation above 100 mm in less than 3–4 h, and the extreme flooding case of 12–13 November 1999 with daily precipitation having reached 550 mm, which led to more than 30 deaths. The ability of a high-resolution (2.5 km) model to forecast the quantitative precipitation associated with these five events is evaluated. Both qualitative evaluations that compare observed and modeled reflectivities or surface precipitation, and quantitative evaluations based on classical scores are performed to assess the quality of the numerical experiments. Starting from the same analysis as the operational models, the high-resolution model improves the results for one of the cases, the extreme flash flood case. For the four other cases, higher...