Graphical Output
Examples of charts
For examples of charts, click on links in the headings below. Further details regarding interpretation of the chart and graphical products are given beneath each product.
Extended Range Graphical Output
Extended range products are available on ecCharts (all these correspond to weekly means):
- Anomaly:
- Temperature of the earth's surface
- 2m temperature
- Total precipitation
- MSLP
- 500hPa height
- Winds at 10m, 100m, 850hPa, 700hPa, 500hPa, 200hPa
- Sunshine duration
- 10hPa temperature
- 10hPa wind
- Absolute:
- 500hPa height
- Probability distribution:
- Temperature of the earth's surface
- 2m temperature
- Total precipitation
- MSLP
- Anomaly probability (for various pre-defined quantiles):
- Temperature of the earth's surface
- 2m temperature
- Total precipitation
- MSLP
- Extreme Forecast Index (EFI) and Shift of Tails (SOT):
- Temperature at 2m
- Total precipitation
Extended range products are available on web open charts (all these correspond to weekly means):
Weekly anomaly - Extended range forecast
The weekly anomaly charts (2m temperature, surface temperature, total precipitation, mean sea level pressure) display the anomaly between the forecast weekly mean and the corresponding weekly mean in the ER-M-climate. The charts are "clickable". Clicking the mouse over any location on HRES or ENS charts will produce probability information in diagrammatic form. Diagrams available:
- Extended anomaly meteogram.
NB: The colour scale of values appropriate to each display may be shown by clicking on the central small icon in the bottom right of the web frame.
Weekly anomaly probability - Extended range forecast
The weekly anomaly probability charts (2m temperature, surface temperature, total precipitation, mean sea level pressure) display the probability that the weekly mean anomalies are greater than zero (i.e. the proportion of ensemble members warmer or wetter etc than ER-M-climate). A particular consideration when using the precipitation charts is that the range of colours available for "below average" anomalies (red colours) is constrained by the local climatology in the ER-M-climate. For example if all ENS members showed a dry week, the mean (-ve) anomaly could be no larger in magnitude than the mean in the ER-M-climate. So in some locations the strongest dry signal one can ever see will only be in the first or the second of the red shades.
White on the plot means that either: the proportion of members above the ER-M-climate mean is between 40 and 60%, or that that proportion, whatever it is, is not statistically significant. The plot structure circumvents the fact that some ER-M-Climate distributions will be skewed, wherein the climatological probability of seeing more than the mean is far from 50%.
Clicking the mouse over any location on HRES or ENS charts will produce probability information in diagrammatic form. Diagrams available:
- Extended anomaly meteogram.
NB: The colour scale of values appropriate to each display may be shown by clicking on the central small icon in the bottom right of the web frame.
Weekly terciles - Extended range forecast
The weekly tercile charts (2m temperature, surface temperature, total precipitation, mean sea level pressure) display the probability that the weekly mean anomalies are in the lower or upper third of the ER-M-climate distribution.
The ER-M-climate is used to define "normal" conditions and three equally probable domains can be defined: below normal, normal and above normal. The probability that one of the many ER-M-Climate outcomes lies within each of these domains is 33%. The upper tercile chart displays the probability, according to the forecast, of lying in the upper tercile (e.g. warmer or wetter etc) and the lower tercile displays the probability, according to the forecast, of lying in the lower tercile (e.g. cooler or drier etc). The probability is calculated from the number of ensemble members which show an anomaly within each domain. If the ensemble distribution is not significantly different from the corresponding ensemble distribution of the ER-M-climate, then the tercile chart will indicate a probability close to 33%. Therefore, the probability range 20-40% is shown in white, to imply "no noteworthy signal".
Clicking the mouse over any location on HRES or ENS charts will produce probability information in diagrammatic form. Diagrams available:
- Extended anomaly meteogram.
NB: The colour scale of values appropriate to each display may be shown by clicking on the central small icon in the bottom right of the web frame.
Multiparameter outlook - Extended range forecast
These multi-parameter charts charts display ENS mean 500hPa geopotential height, and ENS mean anomalies of 2m temperature, 10m wind, and sunshine duration (sunshine duration weekly mean anomalies represent the fraction of time there is sunshine during the weekly mean period. e.g. +0.01 means 1% more sunshine than in the ER-M-climate; -0.05 means 5% less sunshine). This product is available only for Europe.
Clicking the mouse over any location on HRES or ENS charts will produce probability information in diagrammatic form. Diagrams available:
- Extended anomaly meteogram.
NB: The colour scale of values appropriate to each display may be shown by clicking on the central small icon in the bottom right of the web frame.
Monthly forecast plumes - Extended Range forecast
These monthly forecast plume charts charts display the time evolution of the ensemble forecast of 500hPa geopotential, 12hr accumulated precipitation, and temperature at 850hPa over several European cities. The 51-member distribution of real-time monthly forecasts is categorised in 12.5% intervals (shading), and the median is shown as well (solid line). This product is not bias-corrected.
Mean sea level pressure and z500 stamps - Extended range forecast
The mean sea level pressure and z500 stamp charts (also known as "postage stamp charts") show on each panel the weekly mean of one ensemble member forecast of 500hPa geopotential or mean sea level pressure. For mean sea level pressure stamps, the -6°C and 16°C isotherms at 850hPa are also displayed as cyan and red lines respectively. This product is not bias-corrected.
Weather regime clusters - Extended range forecast
The weather regime cluster products are based on a method of regime clustering for the ENS. The weekly mean 500hPa geopotential forecast by each ensemble member is assigned to the closest pattern. The display indicates the number of members that fall within the same cluster and shows the averaged 500hPa geopotential pattern of these ensemble members. This product is not bias-corrected.
The weather regime graphical time series shows the probability of each regime (as measured by the proportion of ENS members in each cluster) in diagram form. This shows the distribution of regime probability at weekly intervals as the forecast progresses.
Hovmoeller diagram or Time-Longitudes diagram - Extended range forecast
Hovmoeller or Time-Longitudes diagrams show the time evolution of the ensemble mean anomaly of a parameter (past above and forecast below the horizontal line). The x-axis represents the longitude, the y-axis represents the time evolution (time increasing downwards).
The northern mid-latitude Hovmoeller diagrams show the time evolution of the ensemble mean anomaly of geopotential height at 500hPa or 1000hPa, averaged over the latitude band 35N-60N (Northern Extratropics) or 25S-50S (Southern Extratropics). The anomaly has been computed by averaging all the members of the real-time forecast and subtracting the mean of the ER-M-climate. Contours are plotted every 1.5dam. Since it is an ensemble mean, the structures shown are much more detailed in the first days of the forecast (top part) than in the last days (bottom part). Shaded areas represent the ensemble spread and are displayed only when the amplitude of the anomaly exceeds 2dam. On average spread will naturally increase with forecast lead time, though occasionally, when moving to longer lead times, there can be a reduction.
The Madden-Julian Oscillation (MJO) Hovmoeller diagrams show the ensemble mean anomalies of outgoing long wave radiation, zonal wind at 850hPa, and velocity potential at 200hPa averaged over a tropical band (15N-15S).
The Madden-Julian Oscillation (MJO) Postage Stamp charts show the Hovmoeller sections of anomalies of outgoing long wave radiation, zonal wind at 850hPa and velocity potential at 200hPa averaged over a tropical band (15N-15S) for each ensemble member (51 stamps).
Large scale mean flow - Weekly mean anomalies 500hPa - Extended range forecast
The mean flow and anomaly charts show, at global or regional scales, the weekly mean 500hPa geopotential height and the anomaly from the corresponding weekly mean 500hPa geopotential height of the ER-M-climate.
Clicking the mouse over any location on HRES or ENS charts will produce probability information in diagrammatic form. Diagrams available:
- Extended anomaly meteogram.
NB: The colour scale of values appropriate to the display may be shown by clicking on the central small icon in the bottom right of the web frame.
Extended Range Verification
The extended range products should always be used with historical skill metrics in mind, as provided by verification probabilistic scores from the re-forecasts as discussed above.
The Anomaly charts (500hPa N Hem anomaly and Global and Regional anomaly) show how past extended range forecasts performed in the lead up to a particular week. The anomaly of one week of forecasts (relative to the ER-M-climate) is compared with the weekly mean anomalies (relative to the ER-M-climate) of recent extended range forecasts verifying over the same period. They give information about the consistency between the monthly forecasts from one week to another.
Updated/Amended 09/07/20 - Added Extended Range Graphical Output.
Updated/Amended 3110/20 - Amended Chart links to open access.
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