Cliff Mass, Professor of Meteorology at the University of Washington, has provided an excellent summary of the drought conditions in California. Note also that Wyoming is doing quite well thus far.
The precipitation totals for all of 2013 were amazing (all in inches). A few examples
Downtown LA 3.60
Santa Barbara 3.95
Paso Robles 1.92
Santa Cruz 4.78
All are all-time records. I could give you a dozen more. The total precipitation for the last three months (see graphic) shows much of California has gotten less than 1.5 inches with large areas not even getting an inch.
Snow pack in the Sierra Nevada is now at alarming levels ranging from 8% of normal in the north to 22% of normal to the south.
A plot of the snow water content in the snow pack for the north, central, and southern portions of the state not only show it is very low, but running lower than the worst snow pack year on record 1976-1977:
California has massive reservoir capacity and the state did get a lot of precipitation in late 2012, but the lack of rain has brought most of the reservoirs to far below capacity, particularly the critical large ones in the northern part of the State (see below).
The big question is whether there will be any precipitation soon over California. The models are pretty emphatic about this: nothing during next week. Here is the probability of getting at least 5 mm (.2 inches) of precipitation during any 24 hr period over the remainder of the month based on one of the best ensemble (many model runs) numerical weather prediction systems (NAEFS, the North American Ensemble Forecasting System). Very low probability of getting even that modest amount. It is even very dry over us in the NW.
The only saving grace for California is that that snow pack over Colorado and environs is above normal and thus the Colorado River, a significant water source for CA should be in decent shape. And the huge capacity of the California’s reservoirs might allow them to squeak by this year.
But this lack of precipitation is bringing major records and is getting very serious. This pattern of dry conditions over the the entire western U.S/southern BC. is different from the pattern suggested by many climate models for the end of the century: very dry over southern and central CA, but wetter over the Northwest and British Columbia.