The western United States (WUS) is frequently subject to adverse impacts of hydroclimate extremes such as droughts and floods, and cascading/compounding impacts including wildfires and amplified heat waves. Record-shattering heat and associated extreme low snowpack during winter 2025/2026 has triggered widespread discussion and motivated additional research on this topic. Anthropogenic forcing can alter temperature, precipitation, and humidity, which affect vapor pressure deficit, evapotranspiration, precipitation phases, snowpack, runoff, and other related processes—thereby shaping the risk of hydroclimatic processes and extremes. It is thus crucial to advance the fundamental knowledge of drivers of hydroclimatic processes and extremes.

This session focuses on recent advancements in understanding hydroclimate and related extremes/hazards in the WUS in terms of physical processes, observations, numerical modeling, and impact analysis. Abstracts that examine droughts, floods, snowpack, wildfires, atmosphere-land interactions—as well as the roles of temperature, precipitation and humidity in driving hydroclimatic processes and extremes—are particularly welcome.

• A - Atmospheric Sciences
• H - Hydrology
• NH - Natural Hazards