Recent decreases in snow water storage in western North America.

Mountain snowpacks act as natural water towers, storing winter precipitation until summer months when downstream water demand is greatest. We introduce a Snow Storage Index (SSI), representing the temporal phase difference between daily precipitation and surface water inputs-sum of rainfall and snowmelt into terrestrial systems-weighted by relative magnitudes. Different from snow water equivalent or snow fraction, the SSI represents the degree to which the snowpack delays the timing and magnitude of surface water inputs relative to precipitation, a fundamental component of how snow water storage influences the hydrologic cycle. In western North America, annual SSI has decreased (p < 0.05) from 1950-2013 in over 25% of mountainous areas, as a result of substantially earlier snowmelt and rainfall in spring months, with additional declines in winter precipitation. The SSI and associated trends offer a new perspective on hydrologic sensitivity to climate change which have broad implications for water resources and ecosystems.

The Role of School-based Group Mentoring in Promoting Resilience among Vulnerable High School Students.

This study examined the role of participation in a year-long school-based group mentoring program, Project Arrive (PA), on increasing resilience during the first year of high school among students identified as being at high risk for school dropout. Participants were 114, ninth grade students taking part in one of 32 PA mentoring groups, and 71 statistically matched comparison students (53% male, 75% eligible for free/reduced-price lunch, 62% Latinx). Using a propensity score with inverse probability of treatment weighting (IPTW) to reduce selection bias, and a multi-level model to account for non-independence of data within mentoring groups, we examined changes from pre-test to program exit on seven external resilience resources (developmental supports and opportunities) and four internal resilience assets (personal strengths). At program exit, PA participants had higher adjusted means than comparisons on six external resources, including school support, school belonging, school meaningful participation, peer caring relationships, prosocial peers, and home meaningful participation. PA participants also had higher adjusted means on one internal asset, problem solving. Results point to the promise of group mentoring as an approach for increasing resilience among academically vulnerable adolescents.