Hydrometeorological Characteristics of Rain on Snow Events Associated with Atmospheric Rivers
Atmospheric rivers (ARs) are narrow, elongated, synoptic corridors of enhanced water vapor transport that play an important role in regional weather/hydrology. Rain on snow (ROS) events during ARs present enhanced flood risks due to the combined effects of rainfall and snowmelt. Focusing on California's Sierra Nevada, the study identifies ROS occurrences and their connection with ARs during the 1998 2014 winters. AR conditions, which occur during 17% of all precipitation events, are associated with 50% of ROS events (25 of 50) Composite analysis shows that compared to ARs without ROS, ARs with ROS are on average warmer by ~2 K, with snow water equivalent loss of ~0.7 cm/d (providing 20% of the combined water available for runoff) and ~50% larger streamflow/precipitation ratios. Atmospheric Infrared Sounder retrievals reveal distinct offshore characteristics of the two types of ARs. The results highlight the potential value of observing these events for snow, rain, and flood prediction.