upslopeSeptember 3, 2026 New England rain event — forecast vs. what fell
event hit rate 66%
MAE 0.23″
32 mountains scored
On September 3, 2026, 19 of 32 scored New England ski resorts recorded measurable rain, peaking at 0.84″ near Sunday River. upslope’s day-before forecasts verified at a 66% event hit rate with a mean absolute error of 0.23″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).
Mountain by mountain
| Resort | Forecast | Measured | Error | Call |
|---|---|---|---|---|
| Sunday RiverME | 0.48″ | 0.84″ | -0.36″ | ✓ |
| Jay PeakVT | 0.51″ | 0.8″ | -0.29″ | ✓ |
| BurkeVT | 0.38″ | 0.61″ | -0.23″ | ✓ |
| Bretton WoodsNH | 0.37″ | 0.59″ | -0.22″ | ✓ |
| WildcatNH | 0.51″ | 0.59″ | -0.08″ | ✓ |
| Smugglers' NotchVT | 0.38″ | 0.54″ | -0.16″ | ✓ |
| StoweVT | 0.44″ | 0.51″ | -0.07″ | ✓ |
| LoonNH | 0.44″ | 0.45″ | -0.01″ | ✓ |
| Waterville ValleyNH | 0.5″ | 0.42″ | +0.08″ | ✓ |
| SaddlebackME | 0.51″ | 0.41″ | +0.1″ | ✓ |
| SugarloafME | 0.58″ | 0.41″ | +0.17″ | ✓ |
| Black MountainNH | 0.5″ | 0.4″ | +0.1″ | ✓ |
| Bolton ValleyVT | 0.55″ | 0.35″ | +0.2″ | ✓ |
| CannonNH | 0.4″ | 0.34″ | +0.06″ | ✓ |
| AttitashNH | 0.46″ | 0.33″ | +0.13″ | ✓ |
| CranmoreNH | 0.44″ | 0.33″ | +0.11″ | ✓ |
| Mad River GlenVT | 0.43″ | 0.24″ | +0.19″ | ✓ |
| GunstockNH | 0.46″ | 0.17″ | +0.29″ | ✓ |
| SugarbushVT | 0.4″ | 0.17″ | +0.23″ | ✓ |
| Pats PeakNH | 0.31″ | 0.09″ | +0.22″ | ✗ |
| RaggedNH | 0.55″ | 0.09″ | +0.46″ | ✗ |
| WachusettMA | 0.09″ | 0.05″ | +0.04″ | ✓ |
| Berkshire EastMA | 0.07″ | 0.04″ | +0.03″ | ✓ |
| CrotchedNH | 0.35″ | 0.04″ | +0.31″ | ✗ |
| Mount SunapeeNH | 0.33″ | 0.04″ | +0.29″ | ✗ |
| PicoVT | 0.59″ | 0.03″ | +0.56″ | ✗ |
| BromleyVT | 0.45″ | 0.02″ | +0.43″ | ✗ |
| KillingtonVT | 0.64″ | 0.02″ | +0.62″ | ✗ |
| Magic MountainVT | 0.36″ | 0.02″ | +0.34″ | ✗ |
| OkemoVT | 0.36″ | 0.02″ | +0.34″ | ✗ |
| StrattonVT | 0.4″ | 0.02″ | +0.38″ | ✗ |
| Mount SnowVT | 0.34″ | 0.01″ | +0.33″ | ✗ |
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.
Forecast = upslope's NWS-based rain forecast for the same 7am-to-7am window the gauges measure, from the last run before that window opened. ✓ = correctly called rain above/below 0.1″. Positive error = over-forecast.