upslopeSeptember 1, 2026 New England rain event — forecast vs. what fell
event hit rate 63%
MAE 0.12″
30 mountains scored
On September 1, 2026, 8 of 30 scored New England ski resorts recorded measurable rain, peaking at 0.25″ near Stratton. upslope’s day-before forecasts verified at a 63% event hit rate with a mean absolute error of 0.12″ across 30 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).
Mountain by mountain
| Resort | Forecast | Measured | Error | Call |
|---|---|---|---|---|
| StrattonVT | 0.41″ | 0.25″ | +0.16″ | ✓ |
| BromleyVT | 0.4″ | 0.24″ | +0.16″ | ✓ |
| Mount SnowVT | 0.4″ | 0.21″ | +0.19″ | ✓ |
| Berkshire EastMA | 0.33″ | 0.2″ | +0.13″ | ✓ |
| Magic MountainVT | 0.35″ | 0.19″ | +0.16″ | ✓ |
| Mount SunapeeNH | 0.28″ | 0.18″ | +0.1″ | ✓ |
| OkemoVT | 0.22″ | 0.14″ | +0.08″ | ✓ |
| KillingtonVT | 0.16″ | 0.11″ | +0.05″ | ✓ |
| PicoVT | 0.15″ | 0.08″ | +0.07″ | ✗ |
| WachusettMA | 0.45″ | 0.05″ | +0.4″ | ✗ |
| Pats PeakNH | 0.29″ | 0.02″ | +0.27″ | ✗ |
| AttitashNH | 0.11″ | — | +0.11″ | ✗ |
| Black MountainNH | 0.12″ | — | +0.12″ | ✗ |
| Bolton ValleyVT | 0.04″ | — | +0.04″ | ✓ |
| Bretton WoodsNH | 0.06″ | — | +0.06″ | ✓ |
| BurkeVT | 0.03″ | — | +0.03″ | ✓ |
| CannonNH | 0.07″ | — | +0.07″ | ✓ |
| CranmoreNH | 0.11″ | — | +0.11″ | ✗ |
| CrotchedNH | 0.36″ | — | +0.36″ | ✗ |
| GunstockNH | 0.2″ | — | +0.2″ | ✗ |
| Jay PeakVT | 0.02″ | — | +0.02″ | ✓ |
| LoonNH | 0.07″ | — | +0.07″ | ✓ |
| Mad River GlenVT | 0.07″ | — | +0.07″ | ✓ |
| RaggedNH | 0.2″ | — | +0.2″ | ✗ |
| Smugglers' NotchVT | 0.03″ | — | +0.03″ | ✓ |
| StoweVT | 0.04″ | — | +0.04″ | ✓ |
| SugarbushVT | 0.07″ | — | +0.07″ | ✓ |
| Sunday RiverME | 0.08″ | — | +0.08″ | ✓ |
| Waterville ValleyNH | 0.1″ | — | +0.1″ | ✗ |
| WildcatNH | 0.13″ | — | +0.13″ | ✗ |
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.