La Niña & El Niño — science-based ski prediction for the Pacific Northwest and Northern Rockies. 45 years of SNOTEL data.
The Pacific Ocean dictates PNW snow. During La Niña, blocking high pressure shifts the storm track north, funneling cold moisture directly into the Cascades and Northern Rockies. La Niña brings deep snow — opposite to the Andes.
Cool Pacific SSTs push the jet stream north, aiming storms at Washington and the Northern Rockies. Snoqualmie and Mt. Baker average 117–121% of normal peak SWE. The strongest La Niña signal in North America.
Near-normal conditions. Storm track position becomes variable, and secondary factors like PDO and MJO gain influence. Higher variance from year to year.
Warm Pacific redirects storms south toward California and the Southwest. PNW resorts suffer — El Niño years average 61–90% of normal SWE. The rain-snow line rises at lower elevations.
Nine SNOTEL stations across four states confirm the La Niña → deep snow pattern with 31–50 years of verified federal data.
Alpine Meadows, WA — the strongest single-station correlation. Negative sign means La Niña (negative ONI) → higher snowpack. p=0.0006 over 32 seasons.
Across WA, OR, WY, and MT, nine of ten SNOTEL stations show statistically significant ONI × SWE negative correlation. Consistent signal across the entire Pacific Northwest.
SNOTEL data spans 1977–2026. The consistency across stations and decades confirms this is a real climate signal, not statistical noise. USDA federal measurement standard.
Selected seasons at Alpine Meadows (Snoqualmie area). Bar = peak SWE as % of long-term mean. La Niña years dominate the top; El Niño years cluster at the bottom.
La Niña sensitivity varies by geography. Washington Cascades respond strongest; the Northern Rockies show a weaker but still significant signal.
A transparent, repeatable framework using NOAA climate indices and USDA SNOTEL snowpack data spanning up to 50 years.
We calculate the Oct–Mar average of the Oceanic Niño Index (ONI) from NOAA's ERSSTv5 dataset. This 6-month winter window captures the full ENSO influence on PNW storm tracks.
For each water year (Oct 1 – Sep 30), we extract the annual maximum Snow Water Equivalent from USDA NRCS SNOTEL stations — an objective, instrument-measured snowpack metric.
ONI × Peak SWE correlation is computed per station. Nine of ten achieve p<0.05 significance, with r from −0.283 to −0.573. Negative sign = La Niña → more snow.
Forecast published each October when NOAA confirms winter ENSO phase. La Niña years → expect above-normal snowfall at PNW resorts. El Niño → plan trips to California or the Andes instead.
ONI (Oct–Mar avg) × annual peak SWE (inches):
The negative correlation is the defining feature of PNW forecasting — shared with Japan (JAPOW r=−0.73) and opposite to the Andes (ANDESPOW r=+0.546).
NOAA CPC — ONI index (1950–present)
USDA NRCS — SNOTEL daily SWE (1976–present)
bestsnow.net — Independent validation reference
NOAA Climate.gov — ENSO phase history