Forecast Map Display

The forecast maps are displayed as follows:

Lower tercile probability

Upper tercile probability

Climatological Lower Tercile

Climatological Upper Tercile

Ensemble Mean Forecast Anomaly
Verifying CDAS Anomaly (when available)

Five fields are currently available (500 mb height, 250 mb zonal wind, 850 mb temperature, sea-level pressure and precipitation).

Anomalies and terciles are relative to a 1979-2001 daily climatology (smoothed with a 31-day running mean).   Forecast anomalies are calculated relative to the climatology of the forecast model (i.e the mean bias is removed). Tercile probabilities are calculated using the retrospective forecast database (see here for a description of the method) and are generally quite reliable (as evidenced by the cross-validated forecast verification statistics).

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