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.
The weekly mean anomaly charts display the anomaly between the forecast weekly mean and the corresponding weekly mean in the ER-M-climate.
Charts available are: 2m temperature, surface temperature, total precipitation, mean sea level pressure, winds.
Click the mouse over any location on the ensemble charts to produce probability information in diagrammatic form. Diagrams available:
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
The weekly anomaly probability charts display the probability that the weekly mean anomalies are greater than zero. The probability is calculated from the number of ensemble members which show an anomaly within the higher half of the the ER-M-climate distribution.
Charts available are: 2m temperature, surface temperature, total precipitation, mean sea level pressure.
Two equally probable domains can be defined: below normal and above normal.
White on the plot means that either:
This plot structure circumvents the fact that some ER-M-Climate distributions will be skewed (i.e. the climatological probability of seeing more than the mean is far from 50%).
Note: On precipitation charts the range of colours available for "below average" anomalies (brown 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 brown shades.
Click the mouse over any location on the ensemble charts to produce probability information in diagrammatic form. Diagrams available:
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
The weekly anomaly probability charts display the probability that the weekly mean anomalies are in the lower or uppermost third (tercile), fifth (quintile) or tenth (decile) of the ER-M-climate distribution.
Charts available are: 2m temperature, surface temperature, total precipitation, mean sea level pressure.
The probability is calculated from the number of ensemble members which show an anomaly within the highest or lowest tercile, quintile or decile of the the ER-M-climate.
Terciles: Three equally probable domains can be defined: below normal, normal and above normal.
Quintiles: Five equally probable domains can be defined:
Deciles: Five equally probable domains can be defined.
Click the mouse over any location on the ensemble charts to produce probability information in diagrammatic form. Diagrams available:
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
These EFI charts aim to point to areas where unusually anomalous temperature or precipitation is likely to occur.
The EFI temperature chart shows the weekly mean EFI for 2 m temperatures. This is derived from the distribution of ensemble forecast 2 m temperatures compared with the temperature distribution in the ER-M-climate.
The EFI precipitation chart shows the weekly mean EFI for precipitation. This is derived from the distribution of ensemble forecast precipitation compared with the precipitation distribution in the ER-M-climate.
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
Experience suggests :
The SOT index provides information about how extreme an event could potentially be. Positive SOT values indicate that at least 10% of the ensemble is forecasting an "extreme event" and a high value shows how extreme:
These multi-parameter charts charts display the ensemble weekly mean:
Click the mouse over any location on the ensemble charts to produce probability information in diagrammatic form. Diagrams available:
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
Hovmöller or Time-Longitudes diagrams show the time evolution of the ensemble mean anomaly of a parameter. The x-axis represents the longitude, the y-axis represents the time evolution (time increasing downwards). Past results lie above the horizontal line and forecast results lie below.
The northern mid-latitude Hovmöller 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 below the horizontal line 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) Hovmöller 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 mean flow and anomaly charts show, at global or regional scales, the weekly:
Click the mouse over any location on the ensemble charts to produce probability information in diagrammatic form. Diagrams available:
Click on the central small icon in the bottom right of the web frame to show the colour scale of values appropriate to each display.
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.
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.