What type of report is issued if there is a significant change in weather conditions?

A SPECI, which stands for "Special Weather Report," is issued to convey significant changes in weather conditions that occur between regularly scheduled METAR reports. These changes may include alterations in visibility, clouds, or hazardous conditions that could affect flight operations. The issuance of a SPECI helps pilots and air traffic controllers stay informed of current weather conditions that may impact safety during flight. In contrast, AIRMETs and SIGMETs are meant for broader weather phenomena affecting multiple flight operations over larger areas; an AIRMET addresses less severe conditions, while a SIGMET is issued for more significant weather events such as severe turbulence or thunderstorms. PIREPs are pilot reports that provide real-time observations from the cockpit but do not serve as official weather reports like the SPECI does.