A hindcast study of the Piedmont 1994 flood: the CIMA Research Foundation hydro-meteorological forecasting chain

Abstract

Between the 4th and the 6th of November 1994, Piedmont and the western part of Liguria (two regions in north-western Italy) were hit by heavy rainfalls that caused the flooding of the Po, the Tanaro rivers and several of their tributaries, causing 70 victims and the displacement of over 2000 people. At the time of the event, no early warning system was in place and the concept of hydro-meteorological forecasting chain was in its infancy, since it was still limited to a reduced number of research applications, strongly constrained by coarse-resolution modelling capabilities both on the meteorological and the hydrological sides. In this study, the skills of the high-resolution CIMA Research Foundation operational hydro-meteorological forecasting chain are tested in the Piedmont 1994 event. The chain includes a cloud-resolving numerical weather prediction (NWP) model, a stochastic rainfall downscaling model, and a continuous distributed hydrological model. This hydro-meteorological chain is tested in a set of operational configurations, meaning that forecast products are used to initialise and force the atmospheric model at the boundaries. The set consists of four experiments with different options of the microphysical scheme, which is known to be a critical parameterisation in this kind of phenomena. Results show that all the configurations produce an adequate and timely forecast (about 2 days ahead) with realistic rainfall fields and, consequently, very good peak flow discharge curves. The added value of the high resolution of the NWP model emerges, in particular, when looking at the location of the convective part of the event, which hit the Liguria region.

A convection-permitting and limited-area model hindcast driven by ERA5 data: precipitation performances in Italy

“…The PIE1994 case was initially analysed by Buzzi et al (1998), who provided an exhaustive description of both the synoptic and small scale meteorological conditions that led to the disastrous flooding of a relatively vast area in northwestern Italy. Recently, several authors (Capecchi, 2020;Cerenzia et al, 2020;Davolio et al, 2020;Garbero and Milelli, 2020;Parodi et al, 2020) produced new reforecasts of the event by using state-of-the-art and limited-area numerical weather models (Meso-NH, COSMO, MOLOCH and WRF), all set in a convection-permitting mode. Although numerical experiments that shortly followed PIE1994 (Buzzi et al, 1998;Ferretti et al, 2000) were able to reproduce the rainfall due to the direct uplift of the flow impinging the Alps, it is by implementing higher-resolution and convection-permitting models that is possible to attain more accurate forecasts.…”

A convection-permitting and limited-area model hindcast driven by ERA5 data: precipitation performances in Italy

“…The PIE1994 case was initially analysed by Buzzi et al (1998), who provided an exhaustive description of both the synoptic and small scale meteorological conditions that led to the disastrous flooding of a relatively vast area in northwestern Italy. Recently, several authors (Capecchi 2020;Cerenzia et al 2020;Davolio et al 2020;Garbero and Milelli 2020;Parodi et al 2020) produced new reforecasts of the event by using state-of-the-art and limited-area numerical weather models (Meso-NH, COSMO, MOLOCH and WRF), all set in a convection-permitting mode. Although numerical experiments that shortly followed PIE1994 (Buzzi et al 1998;Ferretti et al 2000) were able to reproduce the rainfall due to the direct uplift of the flow impinging the Alps, it is by implementing higher-resolution and convectionpermitting models that is possible to attain more accurate forecasts.…”

Detecting Extreme Rainfall Events Using the WRF-ERDS Workflow: The 15 July 2020 Palermo Case Study

“…The innermost domain is centered over Italy and may involve weather radar data assimilation over Italy (reflectivity CAPPI-Constant Altitude Plan Position Indicator-at 2000, 3000, 4000 and 5000 m), alone or in combination with authoritative weather stations over the Italian area. A detailed overview of several validation studies performed by CIMA Research Foundation in mid-latitude areas is reported in [3,4].…”