Q

Qualitative forecasts – forecasts that provide only a categorical value for the predicted variable. Examples of this include “rain/no rain” and “cloudy/partly cloudy”.

Quantitative forecasts – forecasts in which the “amount” of the forecast variable is specified.

Quantitative precipitation forecast (QPF) – a forecast of rainfall, snowfall or liquid equivalent of snowfall.

Quasi-biennial oscillation (QBO) – periodic variation in the direction, either easterly or westerly, of tropical lower stratospheric winds. The direction changes every 26 months.

Quasi-nonhydrostatic (QNH) – pilots, air traffic control (ATC) and low frequency weather beacons use this pressure setting to refer to the barometric altimeter setting that causes the altimeter to read altitude above mean sea level within a certain defined region.

Quasi-stationary front – a front which is nearly stationary or moves very little since the last synoptic position. Also known as a stationary front.