Snow droughts, or below-average snowpack, can result from either dry conditions and/or rainfall instead of snowfall. Monitoring snow drought through time and across space is important to evaluate when snow drought onset occurred, its duration, spatial extent, and severity as well as what conditions created it or led to its termination. We present visualization techniques, including a web-based snow-drought-tracking tool, to evaluate snow droughts and assess their impacts in the western US.

This paper presents an analysis of public responses to U.S. National Weather Service heat-related Facebook posts for the Phoenix (Arizona) County Warning Area to identify community norms that may present challenges to the effectiveness of heat risk communication. Findings suggest that local audiences tend to view heat as normal and the ability to withstand heat as a marker of community identity. Recommendations are provided for harnessing those norms to promote positive behavioral change.

Precipitation partitioning across western US landscapes (1948–present) is estimated by combining gridded precipitation data with freezing level and precipitation data from an atmospheric reanalysis. Spatial patterns and trends in the precipitation phase over elevational and latitudinal gradients are examined. The largest increases in precipitation falling as rain occur during spring. This technique can be used as a diagnostic indicator to inform adaptive water management strategy development.

We examine the timing of early season snowpack relevant to oversnow vehicle (OSV) recreation over the past 3 decades in the Lake Tahoe region (USA). Data from two independent data sources suggest that the timing of achieving sufficient snowpack has shifted later by 2 weeks. Increasing rainfall and more dry days play a role in the later onset. Adaptation strategies are provided for winter travel management planning to address negative impacts of loss of early season snowpack for OSV usage.

Severe wind events in southern California create extreme fire hazards. Sundowner winds are local downslope winds in the Santa Ynez Mountains near Santa Barbara that often coincide with damaging fires. Here we produce a climatology of Sundowner winds and compare their seasonal occurrence and large-scale atmospheric patterns to the well-studied Santa Ana wind regime. We find that Sundowner winds are distinctly different from Santa Ana winds in terms of peak seasonality and synoptic structure.