upslopeSeptember 28, 2026 New England rain event — forecast vs. what fell
event hit rate 91%
MAE 0.26″
32 mountains scored
On September 28, 2026, 31 of 32 scored New England ski resorts recorded measurable rain, peaking at 2.0″ near Wachusett. upslope’s day-before forecasts verified at a 91% event hit rate with a mean absolute error of 0.26″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).
Mountain by mountain
| Resort | Forecast | Measured | Error | Call |
|---|---|---|---|---|
| WachusettMA | 1.7″ | 2.0″ | -0.3″ | ✓ |
| Waterville ValleyNH | 0.41″ | 0.9″ | -0.49″ | ✓ |
| SaddlebackME | 0.23″ | 0.76″ | -0.53″ | ✓ |
| SugarloafME | 0.49″ | 0.76″ | -0.27″ | ✓ |
| AttitashNH | 0.44″ | 0.72″ | -0.28″ | ✓ |
| CranmoreNH | 0.68″ | 0.72″ | -0.04″ | ✓ |
| Berkshire EastMA | 1.12″ | 0.71″ | +0.41″ | ✓ |
| Black MountainNH | 0.51″ | 0.61″ | -0.1″ | ✓ |
| GunstockNH | 0.69″ | 0.54″ | +0.15″ | ✓ |
| WildcatNH | 0.41″ | 0.53″ | -0.12″ | ✓ |
| Pats PeakNH | 0.81″ | 0.48″ | +0.33″ | ✓ |
| Sunday RiverME | 0.23″ | 0.46″ | -0.23″ | ✓ |
| CrotchedNH | 0.98″ | 0.42″ | +0.56″ | ✓ |
| RaggedNH | 0.61″ | 0.4″ | +0.21″ | ✓ |
| LoonNH | 0.2″ | 0.39″ | -0.19″ | ✓ |
| Mount SunapeeNH | 0.74″ | 0.38″ | +0.36″ | ✓ |
| Magic MountainVT | 0.9″ | 0.35″ | +0.55″ | ✓ |
| StrattonVT | 0.87″ | 0.35″ | +0.52″ | ✓ |
| Bretton WoodsNH | 0.12″ | 0.34″ | -0.22″ | ✓ |
| BromleyVT | 0.62″ | 0.34″ | +0.28″ | ✓ |
| PicoVT | 0.47″ | 0.33″ | +0.14″ | ✓ |
| SugarbushVT | 0.22″ | 0.33″ | -0.11″ | ✓ |
| OkemoVT | 0.61″ | 0.31″ | +0.3″ | ✓ |
| Mount SnowVT | 1.09″ | 0.29″ | +0.8″ | ✓ |
| Mad River GlenVT | 0.18″ | 0.27″ | -0.09″ | ✓ |
| KillingtonVT | 0.55″ | 0.26″ | +0.29″ | ✓ |
| Bolton ValleyVT | 0.11″ | 0.24″ | -0.13″ | ✓ |
| CannonNH | 0.2″ | 0.24″ | -0.04″ | ✓ |
| BurkeVT | 0.09″ | 0.13″ | -0.04″ | ✗ |
| StoweVT | 0.09″ | 0.12″ | -0.03″ | ✗ |
| Smugglers' NotchVT | 0.05″ | 0.11″ | -0.06″ | ✗ |
| Jay PeakVT | 0.04″ | 0.03″ | +0.01″ | ✓ |
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.