Because the southern Black Sea is relatively warm (around 13°C or 55°F at the beginning of winter, typically 10 to 6 °C or 50 to 43°F by the end), sufficiently cold air aloft can create significant snowfalls in a relatively short period of time. Due to its location on a peninsula between the Black Sea and the Sea of Marmara, Istanbul is very prone to lake-effect snow and this weather phenomenon occurs almost every winter. This type of precipitation is generated by the warmer Black Sea temperature and colder air temperature, over the Istanbul area. In February 2005, a lake-effect snowfall left of snow, and in March 1987, a three-week-long lake-effect snowfall accompanied with strong winds (lake-effect blizzard) left of snow in Istanbul. The snowfall in the eastern regions of the Black Sea is amplified by the orographic effect of the nearby Caucasus Mountains, often resulting in snowfall of several meters, especially at higher elevations.