upslope

September 27, 2026 New England rain event — forecast vs. what fell

event hit rate 75% MAE 0.47″ 32 mountains scored

On September 27, 2026, 17 of 32 scored New England ski resorts recorded measurable rain, peaking at 0.93″ near Wachusett. upslope’s day-before forecasts verified at a 75% event hit rate with a mean absolute error of 0.47″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).

Mountain by mountain

Resort Forecast Measured Error Call
WachusettMA3.43″0.93″+2.5″✓
CrotchedNH1.39″0.55″+0.84″✓
Magic MountainVT1.38″0.34″+1.04″✓
BromleyVT0.59″0.32″+0.27″✓
OkemoVT0.58″0.31″+0.27″✓
StrattonVT0.93″0.31″+0.62″✓
Berkshire EastMA1.37″0.29″+1.08″✓
Pats PeakNH1.0″0.29″+0.71″✓
Mount SunapeeNH0.89″0.24″+0.65″✓
GunstockNH0.75″0.23″+0.52″✓
RaggedNH0.71″0.21″+0.5″✓
Black MountainNH0.69″0.17″+0.52″✓
Mount SnowVT1.58″0.17″+1.41″✓
CannonNH0.27″0.14″+0.13″✓
AttitashNH0.6″0.13″+0.47″✓
CranmoreNH0.7″0.13″+0.57″✓
LoonNH0.35″0.1″+0.25″✓
KillingtonVT0.57″0.08″+0.49″✗
SaddlebackME0.16″0.08″+0.08″✗
SugarloafME0.26″0.08″+0.18″✗
Sunday RiverME0.32″0.08″+0.24″✗
Waterville ValleyNH0.53″0.08″+0.45″✗
WildcatNH0.63″0.08″+0.55″✗
Bretton WoodsNH0.32″0.07″+0.25″✗
SugarbushVT0.08″0.06″+0.02″✓
Mad River GlenVT0.07″0.05″+0.02″✓
BurkeVT0.02″0.04″-0.02″✓
Bolton ValleyVT0.02″0.03″-0.01″✓
PicoVT0.46″0.02″+0.44″✗
StoweVT0.02″0.01″+0.01″✓
Jay PeakVT0.02″—+0.02″✓
Smugglers' NotchVT——0.0″✓

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