Downstream vs. Headwater: 30 Hour Lead

So now let's look at 30-hour lead time box plots for the downstream point at Newport and compare it to the 30-hour box plot for the upstream point at Williamsburg.

Box Plot of 30-hour Ensemble Forecast Errors Against Observed Value for Downstream Point at Newport
Box Plot of 30-hour Ensemble Forecast Errors Against Observed Value for Headwater Point at Williamsburg

Question

How do the boxplots for downstream point (Newport) compare to those at the upstream point (Williamsburg) at 30 hours? (Choose the best answer.)

The correct answer is c.

Because it takes longer for QPF input to impact the downstream point, there is less spread in the hydrologic forecast ensembles there.