Forecasters expect La Niña conditions to develop this fall and winter. … La Niña is defined by cooler than average sea surface temperatures in the central and eastern Pacific along the equator. The ocean waters affect atmospheric activity, tilting the odds toward drier than normal conditions in Southern California and wetter than average conditions to the far north, especially in the winter…. During the most recent fall and winter, California precipitation mimicked the expected La Niña pattern. … But during the 2022-23 La Niña winter, Central and Southern California faced a flurry of storms fueled by atmospheric rivers, ribbons of water vapor in the sky. Downpours brought flooding across California and snowstorms produced one of the state’s largest snowpacks on record.

Other ENSO and water forecasting news:

• Climate Prediction Center: News release: ENSO diagnostic discussion
• Nature: Communications Earth & Environment: Snow monitoring at strategic locations improves water supply forecasting more than basin-wide mapping
• Phys.org: Hydrologists redefine aridity index to include river and groundwater flow—providing more accurate estimates
• Capital Press (Salem, Ore.): Odds tilt in favor of winter La Niña, National Weather Service says