Where does the wind data come from?
Understand the different sources of wind data, including modelled forecasts, observations, and climatology, and how they are used.
ON THIS PAGE
01Modelled Forecasts
The instrument's forecast comes from the Open-Meteo service, which supplies a best-match blend of global weather models at 10, 80, 120 and 180 metres above ground. These are mathematical models that simulate the atmosphere. The forecast runs for 7 days, or 16 days on the Pro plan and above. Hours that lack the core wind values are dropped and counted, never filled with zeros. Remember that modelled forecasts are for planning support, not on-site measurement. Your own threshold and procedure guide your decisions. You can learn how to read differing models in When models disagree.
02Deterministic Models
Deterministic models give a single forecast. The instrument compares three: ECMWF IFS, GFS and ICON. They are run by different meteorological organisations and use different methods. If their agreement score for an hour is under 60 out of 100, the map chip reads SPLIT, which prompts you to check the exceedance fan and the observation line before relying on one number. Gust is available at 10 m only. For more detail on these models, see ICON, GFS, ECMWF, UKMO.
03Ensemble Models
Ensemble models run the same forecast many times from slightly different starting conditions, creating a range of outcomes called members. The instrument uses three ensembles: GEFS, ECMWF ENS and ICON-EPS. They are available at 10, 80, 100 and 120 m, with gust at 10 m only, and an hour needs at least 10 usable members before odds are given. The P(>limit) value is the fraction of members at or above your limit for that hour. For example, if 10 of 40 members are at or above it, you see 25%. It is raw and uncalibrated, and has not been tuned against past outcomes. Treat it as a measure of forecast disagreement about your limit.
04Observations
Observations are measurements, not forecasts. The instrument searches within 150 km of your place for the latest METAR airport report, from aviationweather.gov, and for buoy reports from NOAA NDBC. It shows the nearest usable one with its age and distance, and flags it as stale if it is more than 90 minutes old. The Ireland pages add Met Éireann stations and the Irish weather buoy network. If no station is usable, the instrument shows UNKNOWN rather than zero, because a missing value is not calm. See Unknown and missing data.
05Climatology and Map Base
Climate context comes from ERA5, a reanalysis dataset from Copernicus. The instrument uses it to build a 16-sector wind rose from the last ten years, within 15 days either side of today's date, and to say how the next 7 days compare with that history. It is shown on /app under the climatology heading. The map base is OpenFreeMap with OpenStreetMap data. The instrument reports wind at your working height, not only the 10 m value in most general forecasts.
06Data Attribution and Licence
Sources are credited in two places. The site footer on content pages carries a DATA ATTRIBUTION line, and the instrument's explainer carries the same credits. They name Open-Meteo, ECMWF IFS and ENS, NOAA GFS and GEFS, DWD ICON, ERA5 from Copernicus, aviationweather.gov METAR, NOAA NDBC, and OpenFreeMap with OpenStreetMap. Open-Meteo data is licensed CC BY 4.0. The instrument is a working tool, and the decision to proceed rests with the person responsible on site, based on their own limits and procedures.
Questions
What is the difference between modelled and measured data?
Modelled data comes from computer simulations of the atmosphere, providing forecasts for future conditions. Measured data comes from physical instruments like weather stations and buoys, providing real-time observations of current conditions. The instrument uses both: models for forecasts and observations to show what is happening now. Forecasts are for planning, while observations confirm actual conditions. The instrument always states the source of the data.
Why does the instrument show wind at my working height?
Wind speed changes with height above the ground. Most general forecasts show wind at 10 metres, but a crane jib, a drone at 100 metres or a rotor hub is in different wind. The instrument interpolates between the 10, 80, 120 and 180 m levels on a logarithmic height scale for any height in between, and extrapolates with a neutral log law below 10 m or above 180 m, labelling it. You can set heights from 2 to 300 m.
What does it mean if the map chip says SPLIT?
It means the agreement score of the three deterministic models (ECMWF IFS, GFS and ICON) is under 60 out of 100 for that hour. It is a prompt to look closely at the exceedance fan and the observation line, because it points to more uncertainty. AGREE means the score is 60 or more. The decision to proceed is always yours.
Can I see how fresh the data is?
Yes. The note at the foot of the inspector gives the fetch time of the forecast, in UTC, and the observation line gives the report's age in minutes. The ensemble readout shows how many members arrived out of those expected. Together these let you judge how recent the information is. How fresh is the data has more.
Why does it show UNKNOWN instead of zero for missing data?
The instrument displays UNKNOWN, or a dash, when data is missing, because a missing value is not calm. If a station is silent, no model level is usable, or an ensemble hour has too few members, showing zero would read as calm, so the gap is marked instead. See Unknown and missing data.