Precpitation downstream of a mesoscale mountain ridge

Predicting precipitation quantities in complex terrain is a difficult task, particularly if the terrain is not resolved in the numerical model at hand. To investigate the connection between resolved flow parameters and the impact of a 700 m high and a 10 km wide mountain ridge, on the precipitation downstream of the mountain ridge, precipitation data has been collected in the Reykjanes peninsula, SW-Iceland for a period of 10 years. Precipitation from two weather stations is compared. One of the stations is located downstream of the mountain range, in the prevailing winds during precipitation, while the other station is receives at the same time winds that have not passed over the mountains. The comparison reveals that warm airmasses and strong low level winds give much more precipitation in the flat land than downstream of the mountains, while during weak winds and/or in cold air, there is little difference in the precipitation.