upslope / scoreboard
Every forecast we publish gets logged, then scored against what volunteer observers actually measured. No cherry-picking. The window is always the last 30 days.
updated 2026-10-23T13:30:10+00:00
Over the last 30 days, upslope’s precipitation forecasts for 32 New England ski resorts verified at a 91% event hit rate across 913 forecast/observation pairs, with a mean absolute error of 0.07″ and an overall bias of +0.01″. Ground truth is the median of CoCoRaHS volunteer gauge measurements near each resort; days with fewer than two reporting gauges are not scored. A forecast that always predicted no rain would have scored 75%.
Snow scoring starts with the first real storms (0 resort-days with 1″+ observed so far; needs 10 to open the score).
| resort | days | avg miss | lean | hit rate |
|---|---|---|---|---|
| Attitash | 29 | 0.05″ | -0.01″ | 93% |
| Berkshire East | 29 | 0.07″ | +0.02″ | 97% |
| Black Mountain | 29 | 0.07″ | -0.01″ | 86% |
| Bolton Valley | 29 | 0.06″ | +0.03″ | 90% |
| Bretton Woods | 29 | 0.06″ | -0.03″ | 97% |
| Bromley | 29 | 0.08″ | +0.02″ | 97% |
| Burke | 29 | 0.05″ | -0.01″ | 83% |
| Cannon | 29 | 0.05″ | -0.01″ | 90% |
| Cranmore | 29 | 0.05″ | +0.01″ | 93% |
| Crotched | 29 | 0.07″ | +0.01″ | 93% |
| Gunstock | 29 | 0.07″ | +0.03″ | 93% |
| Jay Peak | 29 | 0.05″ | +0.03″ | 86% |
| Killington | 29 | 0.07″ | +0.06″ | 86% |
| Loon | 29 | 0.07″ | 0.0″ | 90% |
| Mad River Glen | 29 | 0.04″ | +0.02″ | 93% |
| Magic Mountain | 29 | 0.08″ | +0.02″ | 97% |
| Mount Snow | 29 | 0.1″ | +0.08″ | 97% |
| Mount Sunapee | 29 | 0.07″ | +0.03″ | 97% |
| Okemo | 29 | 0.06″ | 0.0″ | 93% |
| Pats Peak | 29 | 0.07″ | +0.02″ | 93% |
| Pico | 29 | 0.07″ | +0.05″ | 93% |
| Ragged | 29 | 0.06″ | +0.03″ | 93% |
| Smugglers' Notch | 29 | 0.06″ | +0.02″ | 79% |
| Stowe | 29 | 0.07″ | +0.04″ | 79% |
| Stratton | 29 | 0.08″ | +0.03″ | 97% |
| Sugarbush | 29 | 0.05″ | +0.01″ | 97% |
| Wachusett | 29 | 0.07″ | +0.01″ | 97% |
| Waterville Valley | 29 | 0.08″ | -0.01″ | 93% |
| Wildcat | 29 | 0.06″ | -0.01″ | 76% |
| Saddleback | 26 | 0.08″ | -0.04″ | 96% |
| Sugarloaf | 26 | 0.07″ | -0.02″ | 92% |
| Sunday River | 20 | 0.09″ | -0.03″ | 90% |
days = scored forecast/observation pairs · avg miss = how far off, in inches (MAE) · lean = which direction, + means we over-call (bias) · hit rate = correct rain/no-rain calls · tap a column to sort
How this works
Each morning we compare our forecast for the gauges' 7am-to-7am measuring window, from the last run before that window opened, against ground truth: the median of CoCoRaHS volunteer gauge measurements near each resort (25 km radius, widened to 40 km where observers are sparse; days with fewer than 2 reporting gauges aren't scored). Through the fall we score precipitation (rain); once the season starts, the same system scores snowfall. Avg miss is mean absolute error in inches: how far off we were. Lean is the signed average, positive means we over-forecast, negative means we under-forecast. Hit rate is how often we correctly called measurable precipitation (0.1″+), or an inch of snow in season. If our numbers are bad, you'll see it here first.
Scoring fix, Oct 8, 2026: earlier versions compared each gauge report (7am-to-7am) against the forecast for the wrong calendar day; all history was rescored under the corrected rule.