upslope

September 6, 2026 New England rain event — forecast vs. what fell

event hit rate 28% MAE 0.18″ 32 mountains scored

On September 6, 2026, 23 of 32 scored New England ski resorts recorded measurable rain, peaking at 0.54″ near Wachusett. upslope’s day-before forecasts verified at a 28% event hit rate with a mean absolute error of 0.18″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).

Mountain by mountain

Resort Forecast Measured Error Call
WachusettMA0.01″0.54″-0.53″✗
LoonNH0.02″0.51″-0.49″✗
Waterville ValleyNH0.02″0.5″-0.48″✗
Mount SunapeeNH0.02″0.45″-0.43″✗
Sunday RiverME—0.45″-0.45″✗
CannonNH0.02″0.4″-0.38″✗
RaggedNH0.02″0.4″-0.38″✗
GunstockNH0.02″0.25″-0.23″✗
Berkshire EastMA—0.24″-0.24″✗
CrotchedNH0.02″0.24″-0.22″✗
Bretton WoodsNH0.02″0.22″-0.2″✗
Magic MountainVT0.08″0.22″-0.14″✗
SugarbushVT0.05″0.22″-0.17″✗
Pats PeakNH0.02″0.21″-0.19″✗
WildcatNH0.02″0.21″-0.19″✗
Black MountainNH0.02″0.18″-0.16″✗
OkemoVT0.1″0.17″-0.07″✓
AttitashNH0.01″0.13″-0.12″✗
CranmoreNH—0.13″-0.13″✗
Jay PeakVT0.01″0.13″-0.12″✗
Mad River GlenVT0.03″0.13″-0.1″✗
BurkeVT0.02″0.12″-0.1″✗
Bolton ValleyVT0.04″0.1″-0.06″✗
StoweVT0.03″0.09″-0.06″✓
BromleyVT0.09″0.08″+0.01″✓
Mount SnowVT0.09″0.08″+0.01″✓
KillingtonVT0.09″0.06″+0.03″✓
Smugglers' NotchVT0.02″0.06″-0.04″✓
PicoVT0.08″0.05″+0.03″✓
StrattonVT0.1″0.05″+0.05″✗
SaddlebackME—0.04″-0.04″✓
SugarloafME—0.04″-0.04″✓

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