upslope

September 13, 2026 New England rain event — forecast vs. what fell

event hit rate 91% MAE 0.19″ 32 mountains scored

On September 13, 2026, 29 of 32 scored New England ski resorts recorded measurable rain, peaking at 0.73″ near Berkshire East. upslope’s day-before forecasts verified at a 91% event hit rate with a mean absolute error of 0.19″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).

Mountain by mountain

Resort Forecast Measured Error Call
Berkshire EastMA0.79″0.73″+0.06″✓
Mount SnowVT0.87″0.51″+0.36″✓
Pats PeakNH0.47″0.48″-0.01″✓
Mount SunapeeNH0.38″0.47″-0.09″✓
CrotchedNH0.46″0.42″+0.04″✓
RaggedNH0.44″0.42″+0.02″✓
Magic MountainVT0.7″0.4″+0.3″✓
StrattonVT0.65″0.39″+0.26″✓
BromleyVT0.65″0.37″+0.28″✓
KillingtonVT0.69″0.37″+0.32″✓
BurkeVT0.28″0.36″-0.08″✓
OkemoVT0.34″0.35″-0.01″✓
CannonNH0.54″0.34″+0.2″✓
GunstockNH0.38″0.34″+0.04″✓
LoonNH0.53″0.33″+0.2″✓
PicoVT0.68″0.33″+0.35″✓
SugarbushVT0.3″0.33″-0.03″✓
Mad River GlenVT0.43″0.32″+0.11″✓
Bolton ValleyVT0.5″0.31″+0.19″✓
Smugglers' NotchVT0.34″0.3″+0.04″✓
StoweVT0.43″0.29″+0.14″✓
Bretton WoodsNH0.35″0.23″+0.12″✓
WildcatNH0.41″0.23″+0.18″✓
Waterville ValleyNH0.59″0.22″+0.37″✓
AttitashNH0.29″0.14″+0.15″✓
Black MountainNH0.35″0.13″+0.22″✓
CranmoreNH0.33″0.13″+0.2″✓
Jay PeakVT0.5″0.12″+0.38″✓
Sunday RiverME0.34″0.11″+0.23″✓
SaddlebackME0.18″0.03″+0.15″✗
SugarloafME0.15″0.03″+0.12″✗
WachusettMA0.78″0.02″+0.76″✗

Forecast = upslope's last published NWS-based rain number the day before. ✓ = correctly called rain above/below 0.1″. Positive error = over-forecast.