Weather models, comparison and forecast verification

The additional models complement GFS, AIGFS, IFS, AIFS and GEM. They are displayed for comparison and error monitoring. Availability is checked for each location, run, time and variable. A catalogue entry does not mean every map has already been collected.

Maps and meteograms

Interactive meteograms and daily comparisons use data for the selected point. Additional deterministic series are collected at six-hour intervals: intermediate hours and daily values are estimates using interpolation and precipitation apportionment. Lows and highs are not guaranteed to be the true model extremes. Static images labelled GFS remain GFS meteograms.

Each map belongs to a specific run, time and area. “Awaiting collection” is not a forecast. Missing data are never replaced by zeros or another model. Pressure levels at 850/500 hPa appear only when supplied; the additional ensemble feeds do not include 850 hPa or member maps.

New direct maps are collected from DWD, Met Office, Météo-France and JMA. Point forecasts use Open-Meteo. Ensembles and images primarily use Open-Meteo, with official DWD backups for ICON-EU EPS/ICON Global EPS and Met Office for MOGREPS-G, preserving complete real member populations and separate runs. These are separate feeds and can differ in resolution, available run and variables. The public direct JMA grid is 1.25°; this integration uses its six-hour steps through 132 hours. ICON Global is displayed by sampling the nearest triangular cells. UKMO screen temperature is air at 1.5 m.

Elevation and temperature

Additional deterministic models retain native grid temperature and apply one adjustment of 6.5 °C per 1,000 m from that model’s terrain to the known point elevation. This approximation does not resolve inversions or local microclimates. Without a known target elevation, the temperature is not presented as elevation-adjusted for the location.

Maps retain the model-terrain reference. Temperatures at 850/500 hPa do not receive a surface adjustment. Open-Meteo ensembles validate provider-returned elevation without a second adjustment. Direct backups use the nearest native cell and verified model terrain, with one −0.0065 °C/m correction to the requested elevation. MOGREPS-G Direct screen temperature refers to 1.5 m; ICON refers to 2 m. Direct precipitation uses exact six-hour interval sums.

Forecast-point elevation remains the value in the geographic catalogue. New deterministic series select the nearest native grid cell. This is distinct from the land-cell policy in other feeds. Point elevation, model terrain and native temperature are retained separately.

Backtest: what is evaluated

Automatic verification evaluates 2 m temperatures captured before their verification times at identified station locations. Today’s forecast does not create a historical backtest. N counts eligible forecast–observation pairs. MAE is mean absolute error, RMSE is root mean squared error, and bias is the mean forecast minus observation difference.

Native and elevation-adjusted temperatures are evaluated separately. Fair comparison requires matching locations, runs and valid times. Tables also show common N; a smaller error on a different sample does not establish a better model. Lead groups count from first forecast capture; the model run is retained separately. Fourteen common days is a minimum coverage indicator, not automatic approval of model weights.

Direct and Open-Meteo verification samples are stored separately. The public MOGREPS-G archive is typically published about 10–11 hours after its run. Backups never replace a newer complete Open-Meteo image with an older run. Collection resumes in small batches under the shared direct-map traffic and storage bounds. For ensembles, CRPS evaluates the member distribution and Brier evaluates T ≤ 0 °C. Precipitation requires separate quality-controlled observations with matching accumulation periods. Missing verification is shown as pending, not zero error. Additional models retain 0% weight in the production combination.

Regional models for Greece

WRF, SKIRON, BOLAM, ICLAMS and POSEIDON remain under review for numerical data feeds and access conditions. They are not presented as active application feeds without verified data access.

• WRF / BOLAM · NOA
• SKIRON · University of Athens
• ICLAMS · University of Athens
• POSEIDON · HCMR

These links open the providers’ official maps. They are not connected numerical feeds in Xionia. The documented POSEIDON API covers observing platforms and uses OAuth; an atmospheric forecast feed was not verified through it.

Sources and documentation

DWD Open Data · Met Office Open Data · MOGREPS-G official archive · ARPEGE official packages · JMA public GRIB · Open-Meteo / DWD ICON · Met Office · Météo-France · JMA · Ensembles · Open Data