## 2 Materials and Methods  
### Study Region and Data  
Galicia is a region located in the northwest of Spain, ranging from 41\({}^{\circ}\)49\({}^{\prime}\) N to 43\({}^{\circ}\)47\({}^{\prime}\) N in latitude and from 6\({}^{\circ}\)42\({}^{\prime}\) W to 9\({}^{\circ}\)18\({}^{\prime}\) W in longitude, with a total area of 29,574 km\({}^{2}\) (Figure 1). Its relief is low on the coast and higher in the interior, with high plains in the north and mountains and depressions in the southeast (Figure 2). Figure 1: Location of automatic weather stations of MeteoGalicia. As described in [21], the length of its coastline is 2555 km, which is divided into 1659 km of coastal perimeter, 432 km of islands, and 464 km of marshes. Its coastline is abrupt and jagged, with a multitude of inlets and outlets, as well as small islands. The estuaries are one of the particulars of Galicia: they are inlets of the sea on the coast that have been generated by the flooding of the river valleys when the land level descended. The largest urban centres are located next to the estuaries, which are of great fishing importance, thus making the Galician coast one of the most important fishing areas in the world. The interior is made up of low, blunt mountains with a multitude of short-distance rivers with gentle slopes that sometimes give way to rugged slopes. The highest mountains are in the eastern limit of the region: these are Pena Trevinca, with an altitude of 2127 m, and Cabeza de Manzaneda, with an altitude of 1178 m. The central area of Galicia is made up of various lower mountain ranges, between which opens the Lugo plateau with an elevation of about 500-600 m and the Mino valley to the south, with a maximum altitude of 1177 m.  
As a penisular oceanic region, Galicia is among the rainiest in Western Europe, but it has an irregular distribution of rainfall. It is an area that progressively passes from the pure oceanic domain, which determines a homogeneous distribution of the annual distribution of rainfall, to the suboceanic climatic margins or even features a Mediterranean trend. Being located at the southern end of the usual route of the disturbances associated with the west winds, its annual rainfall records should be lower than those registered, but the orography plays a decisive role by firstly intensifying the water discharge when rising the reliefs, thus creating maximum catchment slopes to the windward and rain shadow sectors to the leeward, and secondly by conditioning the uneven distribution of rainfall. For these reasons, it is in the Atlantic areas where the greatest amount of rainfall is collected, while in the inland areas, this amount is less due to the discharge experienced in the first orographic barriers. The distribution of rainfall is quite homogeneous in the north because the valleys and rivers barely modify it; however, in the south it is very heterogeneous due to the great discontinuities of the terrain. The average rainfall in Galicia is 1180 mm, ranging from 500-600 mm in the south to maximums above 1800-2000 mm in the coastal mountains. Of the average total, 337 mm (28%) are collected in winter, 280 mm (24%) in spring, 156 mm (13%) in summer, and 407 mm (35%) in autumn, which is the true rainy season. It is common for springs and summers to be less rainy than winters and authurns: this is the seasonality of rainfall in this region, which increases from north to south. The increase in rainfall in autumn-winter  
Figure 2: Elevation map of Galicia. responds to the predominance of an intense zonal circulation with associated frontal systems that sweep the territory to cause abundant rainfall, especially in the north of the region, because it is where the tail fronts pass with associated storms. In the south, the rains are more seasonal, and they are more related to the advection of highly unstable polar maritime cyclonic air masses from the northwest, as well as maritime tropical air masses from the southwest.