A TTF or Trend Type Forecast also known simply as a Trend, is an aviation weather forecast written by a real person on location at a major airport or military base. A TTF is a professionally considered forecast for weather over a three hour period and is based on an actual weather report, such as a METAR or SPECI.

A TTF is similar to or sometimes in addition to a TAF, a Terminal Aerodrome Forecast, but during the TTF's validity period is considered superior to a TAF.