Research outcomes include:
- Interactions between synoptic and local-scale processes produce several key permutatins of locally-contrasting winter precipitation anomalies.
- Many of sub-regional precipitation patterns delineated in our work are related to regional-scale precipitation patterns and their interactions with finer-scale topography and related local circulation effects.
- Regional-scale precipitation patterns are closely linked to inter-annual variability of large-scale circulation (e.g. position of Pacific-high, position of Aleutian-low, activity of southern jet).
- Although adjacent sub-regions in the Southwest U.S. may be highly correlated with respect to winter precipitation, correlations between sub-regions can become unstable during certain winters, when:
- Large-scale circulation regimes affect the synoptic-scale characteristics of precipitation events in a region over the course of a winter;
- The synoptics of the event favor precipitation in one sub-region over an adjacent sub-region, and precipitation relationships between the sub-regions can become skewed and result in contrasting precipitation anomalies.
- Local topographic features become partially responsible for creating finer-scale differences by amplifying and/or suppressing precipitation at distinct points under different large-scale and synoptic conditions.