High impact weather in the Mediterranean

What is it about?

In the Eastern Mediterranean, the Gulf of Antalya-Turkey was affected by very heavy precipitation (238 mm in 6 h) that resulted in a devastating flash flood on 9 October 2011. Analysis of numerical model products, based on diagnostics and comparison with conventional and remote-sensing observations, indicates that the remarkable amount of accumulated precipitation was strongly modulated by mesoscale effects induced on the synoptic-scale flow. This study investigates the underlying upper- and low-level triggering mechanisms that paved the way for this devastating event. Particular attention is paid to the processes responsible for the instigation, development and maintenance of the event. Using state-of-the-art numerical weather prediction models and ensemble prediction techniques, the aim is to explore the quantitative precipitation forecasting (QPF) performance of this event 72 h in advance.

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Why is it important?

The findings have the following implications for the Mediterranean and also places around the world which bear similar geographical features. (i) Forecasting high impact precipitation events (HIPEs) to 72 h is related to their strong connection to identifiable and predictable synoptic precursors, which establish the mesoscale environment favourable for large precipitation as well as serving as the primary triggering agents; (ii) complex topography and warm sea surface temperatures play very important roles in instigating and sustaining HIPEs; (iii) ensemble-based quantitative precipitation forecasting capabilities to predict HIPEs well in advance, with sufficient space and time accuracy for a suitable alert procedure to take preventive and mitigation actions, may be feasible in cases in which the phenomenon is embedded in dynamical precursors with some degree of predictability.