AMeDAS (Automated Meteorological Data Acquisition System), commonly known in Japanese as "アメダス" (amedasu), is a high-resolution surface observation network developed by the Japan Meteorological Agency (JMA) used for gathering regional weather data and verifying forecast performance. The system began operating on November 1, 1974, and currently comprises 1,300 stations throughout Japan (of which over 1,100 are unmanned), with an average separation of 17 km (11 mi). For about 280 stations (manned or unmanned) located in areas of heavy snowfall, snow depth is also observed.