Latest Global Seasonal Forecasts
The WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble (LC-LRFMME) collects an agreed set of forecast data from 13 WMO accredited Global Producing Centres of Long Range Forecasts (GPCs-LRF) which are part of the WMO numerical long-range forecasting infrastructure and makes available a set of blended products and individual GPC-LRF forecasts in a standard format on its web portal. The probabilistic multi-model ensemble forecasts of surface air temperature and precipitation for the upcoming season from the LC-LRFMME are shown below.
Interpretation: The map in the left-hand pannel shows the spatial pattern of seasonal mean surface air temperature forecast probabilities. Probabilities are calculated for the average temperature for the season being in the highest third (above-normal or warm), middle third (normal) or lowest third (below-normal or cold) ranges of the baseline record (1993-2009) at each location. Colour code is indicated only for the category that has the highest probability of occurrence. For example, for regions highlighted in red, the seasonal mean surface air temperature forecast indicates that the most likely forecast category to occur is warmer than normal. Similarly, the blue color highlights regions where the seasonal mean surface air temperature forecast indicates that the colder than normal category as most likely, while gray color highlights regions where the seasonal mean temperature forecast indicates the near normal category as most likely. Deeper shades of colors highlight increasing probability for the seasonal mean temperature to be in the indicated category. White areas indicate equal chances for all categories.
A particular color does not assure that the seasonal mean temperature is “certain” to be observed in the highlighted most likely forecast category, but rather its probability of being in that category. As a consequence, the observed seasonal mean temperatures have a non-negligible probability to be recorded on a category different from the category indicated on the map as most likely. Users need to take the probabilistic nature of seasonal forecasts into account when making decisions. It should also be noted that the absolute values for the surface air temperature corresponding to the definitions of the above normal (warm), normal or below normal (cold) categories depend on the climatology (historical information) at the location, and therefore, is location-dependent.
The interpretation of the probabilities for the precipitation forecast (right panel) is the same as that for the seasonal mean surface air temperature except that green and red colors indicate whether the forecasted seasonal mean precipitation is most likely to be in the wet or dry category.
Note: These maps are intended to showcase the seasonal forecast products of WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble (LC-LRFMME), and are for guidance purposes only. They do not constitute official forecasts for any region or country. More detailed forecasts, including additional variables and options for selection of regional sub-domains, are available at the LC-LRFMME web portal. Regionally and nationally calibrated and optimized seasonal outlooks for individual regions and countries should be obtained from the relevant Regional Climate Centres, Regional Climate Outlook Forums and NMHSs.
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