Average Annual Winter Precipitation - 4km- Historical and RCM projections

Comparison between simulated projections of change in winter precipitation produced by RegCM3 with boundary conditions from 3 GCMs (GFDL, GENMOM and ECHAM5).
We can also compare the PRISM data and the NCEP-driven RegCM3 simulation of historical conditions. The regional climate model simulates wetter conditions than PRISM provides (interpolations between stations).
Results of simulated change show vastly different results in trends of change between GCMs.
GFDL did not provide climate projections for the intermediate period 2015-2030 but the two other two GCMs provided boundary conditions for RegCM3 for that early period.
ECHAM5-driven simulations show wider spread drought conditions across the domain between 2015-2030 with a particularly dry trend in the Sierras. Moisture returns at least in the northern half of the region by the 2050s.
GFDL-driven results show patches of dry/wet conditions with increased winter rain in mountain ranges.
And contrary to trends in summer precipitation, GENMOM-driven drought winter trends are much stronger later in the century. We see increases in winter precipitation throughout the West in the 2020s but drought conditions in the 2050s in the lower third of the region.