Nowcasting
Nowcasting is very short-range forecasting that uses current observations and conditions to predict what will happen over roughly the next few hours.
Weather radar: A remote-sensing system that detects precipitation and estimates its location, intensity, and motion. Radar reveals storm structure and movement between routine weather-station reports.
Severe thunderstorm warning: An official alert that a severe thunderstorm is occurring or imminent in a specified area. Rapid storm nowcasts support warnings for damaging winds, hail, and intense rainfall.
Weather station: A site equipped to measure atmospheric conditions such as temperature, pressure, wind, and precipitation. Surface stations provide direct measurements that complement remote sensing.
Short-range weather forecasting: Prediction of atmospheric conditions over the next several hours to a few days. This broader horizon extends beyond the immediate conditions targeted by nowcasting.
Satellite meteorology: The use of satellite observations to monitor atmospheric conditions and weather systems. Satellite imagery tracks cloud development and storm evolution across broad areas.
Flash flood warning: An alert that dangerous flash flooding is occurring or expected soon in a specified area. Rainfall nowcasts help identify where runoff may overwhelm streams and drainage systems.
Lead time: The interval between issuing a forecast or warning and the event it predicts. Nowcasts trade long lead times for frequent, detailed updates about imminent conditions.
Numerical weather prediction model: A computer program that simulates atmospheric change from initial conditions using mathematical equations. Model-based forecasts can cover longer horizons, while nowcasts often track observed features directly.
Doppler effect: The change in a wave's observed frequency caused by relative motion between its source and observer. Doppler radar uses frequency shifts to estimate the motion of precipitation.
Aviation weather: Weather information used to plan and conduct aircraft operations safely. Short-term forecasts help aviation manage rapidly changing storms, wind shear, and visibility.