10–30-day extended-range forecast Extended-range weather forecast refers to 10–30-day weather forecast. It is of great value to meteorological disaster prevention and mitigation and sustainable economical and social development, fills time gap between 1–3-day short-range weather forecast, 3–10-day medium-range weather forecast and short-range climate prediction (monthly prediction and seasonal prediction) and meets requirement of establishing complete forecast system. Thus, it is of highlighted scientific value and very high application value and ha………