Model run
Models & data Forecast run Model calculation
A model run is one new calculation by a weather model. It starts with an analysis of current conditions and calculates how the atmosphere may develop.
A new calculation with a new starting point
Stations, satellites, balloons, radar and aircraft supply observations. These and earlier model information are combined into the best available starting state. The model then calculates forwards. That calculation is a model run.
What “00 UTC” means
The label normally identifies the analysis start time. In Germany, 00 UTC is 01:00 in winter and 02:00 in summer. Forecast data are not instantly available at that time: computing, checking and distribution take time. Start time and publication time are different things.
Why the next curve looks different
Fresh observations alter the initial picture. Small differences can grow later, placing a shower at a different time or a few kilometres farther east. The computer has not changed its mind; it has recalculated from different starting conditions.
Comparing runs usefully
- Compare the same area and forecast time.
- Look for developments repeated across several runs.
- When results jump around, consider other models and ensembles.
The newest run has fresher information, but is not automatically the best for every variable. A single curve should not be read as a finished timetable.