The Union of Concerned Scientists recently published an assessment of climate change in California.
 They based their assessment on the results from two global climate models, one with a relatively low sensitivity to CO2 doubling (PCM), and the other with a relatively high sensitivity (HADCM3). 
They looked at outcomes in California for two scenarios.  One is Òbusiness as usualÓ scenario, that envisages fossil fuel emissions increasing at approximately the same rate as present for the remainder of the 21st century.  The other is a lower emissions scenario, where emissions continue to increase but at a lower rate, stabilizing around 2050, then declining to levels below the present level by 2100.
There are therefore two scenarios for each model, giving a range of possible outcomes for California. 
The global modelsÕ resolutions are on the order of 200 km.  Regional details have been supplied by a regional climate model.