Forecast models show over 90% likelihood of atmospheric river conditions along the Southern California coast on Wednesday and Thursday, December 31 and January 1, 2026.
Integrated vapor transport (IVT) values are forecast to reach at least 250 kg m⁻¹ s⁻¹, signaling a moderate-strength event. By Friday, January 2, probabilities remain high, above 70%, for northern and central California as the second and stronger system approaches the coast.
Ensemble control forecasts classify the first event as an AR 1 to AR 2, and the second as a solid AR 2. Confidence in these systems has increased sharply in recent days compared to earlier model runs from December 27, which indicated minimal AR potential…