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The Ensemble Spread Dashboard displays probabilistic forecast data from the NOAA GEFS (Global Ensemble Forecast System), ECMWF IFS, ECMWF AIFS and UK Met Office MOGREPS-G ensemble models using box & whisker charts. It shows the level of agreement, or uncertainty, between ensemble members for a given location and forecast period.
Each chart represents a single weather variable. The box shows the interquartile range (25th to 75th percentile), while the whiskers extend to either the 10th and 90th percentiles or the full minimum–maximum range, depending on the selected Whisker Mode. The median is shown as a line through the centre of the box.
Use the Show Steps filter to focus on a specific time of day throughout the forecast period. For example, selecting 12Z displays only midday values for each day, making trends easier to compare.
The Quick Select buttons allow you to choose a predefined city, or you can select a specific grid point using the latitude and longitude dropdowns. Charts update automatically when switching between model sources, runs, or whisker modes, no page reload is required.
The median always splits the box into two halves containing equal numbers of members, telling you about the shape of the distribution. Median near the bottom of the box (more blue above) means the distribution is positively skewed — the 25% of members between P25 and P50 are clustered close together with similar values, while the 25% between P50 and P75 are more spread out toward higher values. Median near the top of the box (more green below) means the opposite — negative skew.
Please note: Full functionality—including location selection, historical runs, and access to ECMWF and MOGREPS-G data—requires a Premium membership. Log in or upgrade your account to unlock all features.