How do rainfall levels differ between the Tyrrhenian and Adriatic slopes of the Apennines?

Rainfall levels in the Apennine Range are generally higher on the western, or Tyrrhenian, slopes than on the eastern, or Adriatic, side of the mountains.1

While the Apennines as a whole experience moderate amounts of precipitation, the Tyrrhenian slopes benefit from exposure to prevailing southwesterly winds and the influence of the sea. In contrast, the Adriatic coast is typically drier. Across the range, average annual rainfall on the Tyrrhenian slopes ranges between 40 and 80 inches (1,000 and 2,000 mm). As a general rule, the Tyrrhenian coast is both warmer and wetter than the Adriatic coast.21