Abstract. Recent recurring episodes of heavy flash floodproducing rainfall events on the Veneto coastal area have renewed the interest in documenting the frequency and key dynamical ingredients of such events. A climatological analysis of the precipitation in Veneto reveals that, in comparison with the rest of the region, the coastal area is characterized by fewer rain days, lower rainfall accumulations, yet more days with heavy precipitation. If set in relation to the yearly rainfall, daily accumulation can reach values as high as 40 % of the yearly total rainfall, more regularly between 15 % and 30 %, often in periods of 12 h or less.Four such heavy rainfall events were analyzed and synthetically described to highlight key ingredients which appear instrumental in producing the high rainfall accumulations. These comprise an upper-level trough elongating or cutting off into the Western Mediterranean basin after a period of one to two weeks of anticyclonic fair weather conditions with temperatures above normal. The moisture supply over the Adriatic onto north-eastern Italy is favoured by above normal sea surface temperatures, enhanced advection by a surface low in the Gulf of Genoa, and in three of the four cases, an additional surface low over southern Italy. The air flows associated with the upper-level trough for the cases discussed were of moderate to weak intensity, and convectively conditionally unstable. The flow intensity was such that the lower tropospheric portion was blocked by and forced to flow around the Alpine barrier, i.e. manifesting as a north-easterly, low-level flow over much of the north-eastern Italian plains. This blocked flow seemed to interact with the larger-scale synoptic flow to form a distinct and persistent low-level convergence in the area of the Veneto coast.It is suggested that these low-level convergence patterns are key in releasing the convective instability present in the larger-scale flow just on the Veneto coastal area. Hereby, it is the synoptic rather than the convective setting which dictated the observed timescales of intense rainfall. Therefore, the convective rainfall rates paired with the synoptic durations combine to produce the exceptionally high rainfall accumulations observed. Cases like these are significant contributors to forming the coastal precipitation climatology, which for this area is found to be distinctly different than for the rest of the region in terms of precipitation concentration.

Background Asthma still represents a cause of death and hospital admissions worldwide. Our study aimed at analyzing the trend of Emergency Room (ER) asthma admissions in Northeast Italy in order to investigate the relevance of specific patient-related determinants and environmental triggers (pollens, mold spores, and pollutants). Methods Retrospective data from admissions for asthma exacerbations registered between the years 2013 and 2015 in two main ERs in Northeast Italy were collected. Data about patients' age, sex and nationality were recorded. Classification of disease severity followed the current Italian ER triage scoring system (white: no need for emergency treatment; green: need for fast treatment; yellow: severe condition; red: life-threatening condition). Data on pollen/mold spore counts and pollutants were analyzed. Results Overall, 1745 ​ER admissions for asthma were registered, with a persistent and significant increase year by year. A slight prevalence of females and patients over 50 years old was observed. Immigrants accounted for 32%, 36% and 26% of admissions respectively in 2013, 2014 and 2015. The prevalence of immigrants' admissions was significantly higher when comparing the relative ratio of immigrant populations/Italian nationals (p ​< ​0.05). The admissions were coded as follows: white, 6.30%; green, 35.36%; yellow, 39.37%; red, 18.97%. People aged ≥50 years were more frequently admitted with a red code, but the trend was not statistically significant (p ​= ​0,0815). By contrast, amongst immigrants there was a higher prevalence of white and green codes observed in comparison with Italian nationals. Grass pollen peak and PM 10 high levels represented environmental determinants of ER admissions increase. Conclusions The increasing rate of asthma-related ER admissions highlights the need for implementing asthma control strategies. Investigating the traits of patients referring to ER for asthma exacerbations, as well as environmental-related determinants, may help in identifying at-risk individuals and in orienting preventive strategies accordingly. Immigrants represent the most vulnerable sub-population, and their potential difficulties in accessing treatments and health services should be specifically addressed. Overall, implementing patient education in order to improve treatment adherence, as well as providing an asthma action plan to every asthmatic patient, continue to be the most urgent needs.

Abstract.A case of snow fall in the plains of the Northern Italian region Veneto is presented from a forecasters' perspective. Contrasting forecast guidance came from the ECMWF global model and the limited area model LAMI. The former showed a marked warm-moist Sirocco flow coming from the Adriatic Sea onto the coast at all levels, the latter discerned a distinct cold air flow from the north-east along the foothills of the Alps. The integrated observing network of the Centro Meteorologico di Teolo ARPA Veneto revealed this cold-air structure and helped the forecaster in the choice of the forecast and underpin the snowfall alert to the road authorities. It is argued that this feature is a crucial element for the occurrence of snowfall over the Veneto plains, and that the high-resolution numerical weather prediction model was essential in describing this mesoscale feature. The nature of the north-easterly flow is thought to be a combination of a Bora like flow and a barrier jet induced by flow blocking by the Alps.

No abstract

Abstract. In this study consideration is given to the potential use of radar-derived quantitative precipitation estimates (QPE) as flash flood guidance in the context of the Italian Civil Protection flood risk management system. The interest in high precipitation intensities and accumulation motivated the case study of the 26 September 2007 event, in which a quasi-stationary mesoscale convective system brought within 3-6 h 40% of the mean annual precipitation to the wider Venice-Mestre area, i.e. 260 mm in Venice-Mestre and 325 mm in closeby Valle Averto.Comparison of the radar-derived QPE in the area with the rain gauge network revealed a good correspondence for warm season rainfall, both for daily accumulations in the longterm (about 2 years) and hourly accumulations for the case under consideration. The long term average radar to gauge ratio is very close to 0 dB with an uncertainty of approximately ±3 dB, i.e. roughly a factor of two, slightly better for higher precipitation intensities. For the hourly accumulations during this very intense event the spread is similar, while the average is slightly positive.The locations of the rainfall accumulation maximum as detected, respectively, by the radar and by the rain gauge network do not coincide. Given the relatively good quality of the precipitation estimation, it is argued that these areas effectively have received even larger rainfall amounts, and that it is worthwhile to further investigate the potential of radar to be used as flash flood guidance.