*2.2. Climatic Setting*

The Abruzzo Region climate is affected by the physiographic and morphological setting of the Central Apennine Chain and its eastern front in the proximity of the upper watershed divide. This geographic position, located not far from the Adriatic Sea—approximately 40 km as the crow flies—largely influences the climate setting, varying from a Mediterranean type along the coasts and the hilly piedmont areas to a more temperate and continental type in the chain area [70,71]. The morphological arrangement also regulates the rainfall distribution; the highest annual rainfall values (up to 1500–2000 mm/y) occur along the main ridges and in the inland sectors, decreasing down to ~600 mm/year along the hilly piedmont and coastal areas. It is occasionally characterized by heavy rainfall events (>100 mm/d and 30–40 mm/h) [72–74]. The average temperature values range between 8 and 10 ◦C in the mountain sectors (average minimum values of 0–5 ◦C at high elevations) and between 16 and 18 ◦C along the coast. The winter temperature (average January values) shows low values in the inland areas (0–2 ◦C, with minimum values of approximately −5 to −10 ◦C at high elevations) and higher ones (8–10 ◦C) in the hilly piedmont sectors. Over the past two decades, the Abruzzo Region has been affected by some heavy rainfall events and snowstorms, generated by heavy rainfall ranging from 60 to 100 mm in a few hours to >200 mm per day and by snowfall up to >100 cm/day (e.g., January 2003, April 2004, October 2007, March 2011, September 2012, December 2013, February-March 2015, and January-February 2017 [75]).

More in detail, the mountainous landscape and the homogeneous aspect exposure distribution with north exposed slopes determines a harsh climate poorly mitigated by the maritime influence, as confirmed by the presence of the Calderone glacier—the southernmost one in Europe [64,76].

The Abruzzo Apennine chain sector represents an orographic barrier able to strongly diversify the effects of atmospheric currents on its slopes, with upwind (Stau) and downwind (Föhn or, locally, "Garbino") flows that rule and modify the spatial and altitudinal distributions of rainfall and snowfall events [77,78]. Inland sectors, according to their upwind exposure to cold polar currents moisture-laden after transit through the Adriatic and/or Tyrrhenian sides, are characterized by intense and frequent rainfall events [79]. Furthermore, even if, in such a climatically dynamic framework, it is not uncommon to detect minimum winter temperatures around −25 ◦C, the Central Apennines (i.e., Abruzzo and Molise regions) show geomorphological situations that determine the presence of a cold air pool. About this, the absolute minimum values were recorded in recent times in several intermontane plains at an elevation ranging from 1200 to 1500 m a.s.l., such as the Piane di Pezza Plain (−37.4 ◦C), Cinquemiglia Plain (−30 ◦C), Campo Felice Plain (−32 ◦C), and Marsia Plain (−36 ◦C) [80].

According to previous analyses and data [70,71,81,82], the study area is characterized by transitional thermal–meteoric features that largely influence the climate setting varying from continental sub-Apennine to sub-Mediterranean Apennine regimes, considering its southern latitudinal location and the relatively small distance from the Adriatic Sea, which exerts a strong maritime influence.

#### **3. Materials and Methods**

The study area was investigated through an integrated and multidisciplinary approach (Figure 3) based on (i) a morphometric analysis, (ii) geomorphological analysis, (iii) climatic analysis, (iv) nivological analysis, and (v) analysis for the assessment of snow avalanche hazard, supported by the combination of literature data and GIS-based techniques.

**Figure 3.** Schematic flowchart diagram showing the main methodological steps.
