**3) AR Scale Ensemble Diagnostics**

** Top left:** The plume diagram represents the integrated water vapor transport (IVT) forecast for each of the 20 perturbed GFS ensemble models (thin gray lines), the unperturbed GFS control forecast (black line), the 20-member ensemble mean (green line), the maximum ensemble value at that forecast hour (red line) and minimum ensemble value at that forecast hour (blue line). The white shading represents the +/- 1 standard deviation forecast from the ensemble mean. Colored shading represents the AR scale forecast for the given time, shaded according to scale, calculated using the GFS control forecast.

**Shading represents the probability of AR Scale conditions at the given location calculated by the number of ensemble members predicting a given AR Scale at each forecast lead time.**

*Bottom left:***Dots on the map represent the maximum AR Scale forecast from the GFS control members at that grid point for the next five days. Colored shading represents the GFS 7-day accumulated precipitation forecast. The enlarged dot indicates the location the other plots in this diagram are representative of.**

*Top right:***AR Scale magnitude and timing calculated for each GFS ensemble members shaded according to scale. Values in shading represent the magnitude and timing of maximum IVT during each forecasted AR. Gray shading in each panel represents IVT >250 (kg m**

*Bottom right:*^{-1}s

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