Illustrating Ensemble Predictability across Scales Associated with the 13–15 February 2019 Atmospheric River Event

The “Valentine’s Day” atmospheric river (AR) event that affected a majority of California during 13–15 February 2019 ranked as an AR3 (Ralph et al. 2019) along most of the California coast and reached AR4 intensity in Southern California. The strong onshore flow and dynamically favorable characteristics of the Valentine’s Day AR produced both an intense and long-duration precipitation event resulting in widespread hydrometeorological impacts across California. Palomar Observatory in northern San Diego County observed \u3e10 in. (\u3e254 mm) of precipitation in 24 h, the highest 24-h accumulation since record keeping began in 1943 (Hatchet et al. 202