Every five minutes the site records the arrive now figure it is showing for each direction. When the Corps later logs a recreational lockage, the figure recorded just before that arrival is compared with the actual arrival-to-clear time from the Corps' own record. Only lockages within ten minutes of a figure recorded earlier the same day count: a figure shown twenty minutes earlier was somebody else's decision, and the day boundary is a hard one. The comparison is made from the Corps' records after the fact, not live, because those records post about a quarter of an hour behind the water. The 1-hour and 2-hour cards are checked the same way, against the lockages that arrived 60 and 120 minutes after their figure was recorded. The next-day, hour-by-hour forecast is checked on its own page.
A comparison is one recreational lockage (one chamber load, which may hold several boats) against the figure recorded up to ten minutes before it arrived. Error is actual minus forecast, so a positive bias means the forecast ran low.
| Figure | Comparisons | Within 15 min | Median error | Bias | Band coverage |
|---|
"In 1 hour" and "In 2 hours" are the cards' numbers, compared with the lockages that arrived 60 and 120 minutes after the number was recorded. An arrival less than an hour into the day has no 1-hour comparison.
| Card and verdict | Comparisons | Forecast median | Actual median | Median error |
|---|
A blocked verdict should be followed by longer transits than a clear one.
| State when recorded | Comparisons | Forecast median | Actual median | Median error |
|---|
Clear and blocked are the live commercial verdicts; "commercial in the locks" is a vessel in a chamber whose effect on this direction was not yet decided; "no live view" is the feed-only figure shown when AIS was unavailable.
| Direction | Comparisons | Forecast median | Actual median | Median error |
|---|
| Day | Comparisons | Forecast avg | Actual avg | Bias | Error | 1 h error | 2 h error | Figures recorded |
|---|
Error is the mean absolute error in minutes; the 1 h and 2 h errors are the median absolute error of that card's comparisons, blank when the day had none. Figures recorded is how many five-minute readings the log holds for the day; 288 is a full day.
| Time | Direction | State | Forecast | Band | Actual | Error |
|---|
Minutes, Pacific clock time. The band is the forecast's middle half (25th to 75th percentile). Red: more than 15 minutes out; green: within 10.