upslope

September 18, 2026 New England rain event — forecast vs. what fell

event hit rate 59% MAE 0.29″ 32 mountains scored

On September 18, 2026, 25 of 32 scored New England ski resorts recorded measurable rain, peaking at 1.21″ near Pats Peak. upslope’s day-before forecasts verified at a 59% event hit rate with a mean absolute error of 0.29″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).

Mountain by mountain

Resort Forecast Measured Error Call
Pats PeakNH0.29″1.21″-0.92″✓
RaggedNH0.25″1.1″-0.85″✓
Mount SunapeeNH0.27″1.07″-0.8″✓
GunstockNH0.35″0.9″-0.55″✓
CrotchedNH0.35″0.81″-0.46″✓
PicoVT0.06″0.75″-0.69″✗
StrattonVT0.06″0.75″-0.69″✗
BromleyVT0.06″0.72″-0.66″✗
Magic MountainVT0.06″0.71″-0.65″✗
OkemoVT0.11″0.71″-0.6″✓
KillingtonVT0.07″0.65″-0.58″✗
Mount SnowVT0.05″0.37″-0.32″✗
Berkshire EastMA0.14″0.27″-0.13″✓
LoonNH0.08″0.2″-0.12″✗
Black MountainNH0.12″0.18″-0.06″✓
WildcatNH0.01″0.18″-0.17″✗
AttitashNH0.1″0.17″-0.07″✓
CranmoreNH0.15″0.17″-0.02″✓
Sunday RiverME0.02″0.16″-0.14″✗
SaddlebackME—0.15″-0.15″✗
SugarloafME—0.15″-0.15″✗
Waterville ValleyNH0.13″0.15″-0.02″✓
Bretton WoodsNH0.07″0.14″-0.07″✗
CannonNH0.09″0.12″-0.03″✗
WachusettMA0.36″0.1″+0.26″✓
Jay PeakVT0.02″0.04″-0.02″✓
SugarbushVT0.04″0.04″0.0″✓
BurkeVT0.02″0.03″-0.01″✓
Mad River GlenVT0.03″0.03″0.0″✓
Bolton ValleyVT0.01″0.02″-0.01″✓
Smugglers' NotchVT0.01″0.02″-0.01″✓
StoweVT0.01″0.02″-0.01″✓

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