Speci

SPECI is a special meteorological observation used in aviation weather reporting to convey significant changes in weather conditions at an airport between routine hourly METAR observations. It is part of the METAR/SPECI system operated by national meteorological services and coordinated internationally through the World Meteorological Organization. A SPECI provides timely updates intended to inform flight operations and air traffic control when conditions may affect safety or efficiency.

A SPECI is issued when weather changes deteriorate or improve sufficiently to impact flights. Triggers include rapid changes in wind speed or direction, visibility, or cloud ceiling, as well as the onset or cessation of significant weather phenomena such as thunderstorms, heavy precipitation, fog, snow, or icing. The decision to issue a SPECI is typically made by the on-duty weather observer or by automated systems that monitor thresholds.

The content of a SPECI is similar to a METAR and includes wind, visibility, present weather, cloud cover, temperature and dew point, and altimeter setting. It may also include remarks such as runway visual range or noteworthy weather phenomena. Like METARs, SPECI reports are produced in standardized formats and transmitted through aviation weather networks for pilots, air traffic controllers, and operators.

In practice, SPECI reports provide timely, localized updates between hourly observations, helping to support decision-making for departures, arrivals, and en route operations. They are not routine; they are issued only when significant weather changes warrant immediate dissemination.