Target Date Issue Date Lead Time

Forecast made for
located in or near

Probability of Exceeding

Probability Distribution

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Precipitation Flexible Seasonal Forecast

This seasonal forecasting system consists of probabilistic precipitation seasonal forecasts based on the full estimate of the probability distribution.

Please refer to our licensing agreement for permission to use any IRI forecast material.

Probabilistic seasonal forecasts from multi-model ensembles through the use of statistical recalibration, based on the historical performance of those models, provide reliable information to a wide range of climate risk and decision making communities, as well as the forecast community. The flexibility of the full probability distributions allows to deliver interactive maps and point-wise distributions that become relevant to user-determined needs.

The default map shows the seasonal precipitation forecast probability (colors between 0 and 1) of exceeding the 50th percentile of the distribution from historical 1982-2010 climatology. The forecast shown is the latest forecast made (e.g. Dec 2017) for the next season to come (e.g. Jan-Mar 2018). Four different seasons are forecasted and it is also possible to consult forecasts made previously. The forecasts are directly computed from the extended logistic regression model as probabilities of exceeding (or non-exceeding) of every 5th percentile of the climatological distribution. The specific quantile (in steps of 5%) can then be selected. The user can also specify the historical quantitative value (here seasonal total precipitation in mm) for probability of exceeding or non-exceeding.

Clicking on a point on the map will show the local probability of exceeding and probability distribution of the forecast (green) together with the climatological distribution (black).

Colors Scales

Color scales are colors indicating that the distribution of the forecast tends towards drier (shades of brown) or wetter (shades of blue) conditions than normal (moccasin).

Release dates

Our seasonal forecasts are released on the 15th of each month. If the 15th falls on a weekend or holiday, they are released on the closest workday, earlier or later.

Dataset Documentation

Forecast ELR coefficients: 1˚ spatial resolution multi-model ensemble mean and ELR coefficients available here.

Historical precipitation: ELR coefficients derived from the CPC-CMAP-URD dataset available here at 1˚ spatial resolution.



Contact with any technical questions or problems with this Map Room.