Developing an index for heavy convective rainfall forecasting over a Mediterranean coastal area

M Korologou,H Flocas,H Michalopoulou

doi:10.5194/nhess-14-2205-2014

Abstract

Abstract. Heavy convective rainfall incidents that occurred over western coastal Greece and led to flash floods are analyzed with respect to mesoscale analysis for the period from January 2006 to June 2011. The synoptic scale circulation is examined throughout the troposphere along with satellite images, lightning data and synoptic observations of weather stations. Well-known instability indices are calculated and tested against synoptic observations. Taking into account the severity of the incidents, the performance of the indices was not as good as expected. Further detailed analysis resulted in the development of a new index that incorporates formalized experience of local weather and modeled knowledge of mechanisms of severe thunderstorms. The proposed index named Local Instability Index (LII), is then evaluated and its performance is found to be quite satisfactory.

Highlights

Thunderstorms accompanied by heavy rainfall often lead to flash flood events with disastrous consequences on the economy, the environment and, in some cases, have resulted in fatalities
In order to estimate the instability, thermodynamic indices have been created by combining related meteorological parameters (Showalter, 1953; George, 1960; Boyden, 1963; Jefferson, 1963a; Jefferson, 1963b; Miller, 1967; Litynska et al, 1976; Peppler, 1988; Peppler and Lamb, 1989; Jacovides and Yonetani, 1990; Reuter and Aktary, 1993; Tian and Fan, 2013)
The objective of this study is to examine the thermodynamic environment of severe thunderstorms with respect to heavy rainfall occurring in this area for the period of 1 January 2006 to 30 June 2011

Summary

Introduction

Thunderstorms accompanied by heavy rainfall often lead to flash flood events with disastrous consequences on the economy, the environment and, in some cases, have resulted in fatalities. In order to estimate the instability, thermodynamic indices have been created by combining related meteorological parameters (Showalter, 1953; George, 1960; Boyden, 1963; Jefferson, 1963a; Jefferson, 1963b; Miller, 1967; Litynska et al, 1976; Peppler, 1988; Peppler and Lamb, 1989; Jacovides and Yonetani, 1990; Reuter and Aktary, 1993; Tian and Fan, 2013) These indices have not always shown satisfactory results due to local effects that are not well represented or due to limited data sets. It has been shown that the performance of the indices depends on the season or even month, the terrain of the area and the type of the thunderstorms (Michalopoulou and Jacovides, 1987; Prezerakos, 1989; Dalezios and Papamanolis, 1991; Haklander and Van Delden, 2003; Tyagi et al, 2011)

Objectives

Methods

Findings

Conclusion