meteoblue generally uses 2 model runs per day. These runs are based on the assimilations for 00:00 UTC and 12:00 UTC. Initialisation generally takes place 2 hours after assimilation. Updates are made between 6 and 8 hours after assimilation. Depending on the update timing by the customer, the last change may be visible - this depends also on the cache settings of the servers and the user. In unstable weather, these changes may be significant.
With some (mainly regional) models, the updates may be made 4-8 times per day.
Some of our website diagrams (mainly meteograms) and data packages receive hourly updates (post-processing) based on measurement data. Information thereabout is displayed in the respective Help text. If a forecast for the same location is made using different data packages, these may show different values for the variables which are modified by post-processing. In some cases, this may lead to substantial differences. Further differences originate from different sources, which use different forecast models.
There are 3 types of post-processing methods:
Using 1 year of historic measurement data to correct the forecast for a particular variable (temperature, relative humidity, windspeed, radiation). The correction requires 1 year of hourly measurement data from a weather station.
Using 1 week of recent measurement data to correct the forecast for particular variables (temperature, relative humidity, windspeed, radiation). This requires measurement data with less than 1 day delay.
Using the past 1 hour of measurement data to correct the forecast for a particular variables, such as temperature, relative humidity, wind speed, radiation, precipitation (in some areas). This requires near real-time updates, and depends on availability, region, and source.
Weather data are constantly updated as the weather evolves.
Weather data based on measurements are updated when measurement data become available.
To update weather data, meteoblue uses the following prioritisation scheme:
- Global weather models: these are globally available sources of information and supply most weather variables. They are updated usually twice a day, though they are also frequently the least accurate of all available sources.
- Regional weather models (also called "LAM" = local area model): these cover most regions of interest (with a "domain") and supply all necessary weather variables. They are updated 2(-8) times a day, and are more precise than global models.
- Observations: these are mostly based on remote sensing (such as satellites, radar), and are available for certain regions. Update intervals vary between 6 hours and 5 minutes, depending on the source and region. Variables detected (such as cloud cover, precipitation) are used to adjust the simulations (e.g. cloud cover and radiation, rainfall) in a process, in which observation and simulation are matched using plausibility checks.
- Measurements: these are mostly obtained from weather stations. Update intervals vary between 12 hours and 5 minutes, depending on the station and variable. Station data are used to update information in the surroundings for the measured variables, if they are available, and for any locations in the surroundings that have similar conditions to the station, such as the altitude and the proximity. If there are no updates from the station, or if the chosen location has different altitudes (although it may be close to the station), then the measurements will not be used for updating.
Most updates are not archived. Historic data are available for each of these data sources, and possible corrections can be made using comparisons between the different data sources.
A schematic example of updates is shown for 4 locations (with and without actual measurements) and 3 update timings:
(Legend for data source: n=Model; m=MOS, o=Observation: x = not available. AX= update time)
|Location with historical and current measurements|
|Location with historical (and without current) measurements|
|Location with (no historical) and current measurements|
|Location without measurements|
With 2 model runs per day, starting at 00 and 12 UTC, the resulting forecast range of 168 hours will vary by timezone. The resulting forecast hours available (in local time) are displayed in the following graph: