California's worsening drought reached a new, ominous milestone this week just as the typical dry season begins for much of the state.
The National Drought Mitigation Center's weekly U.S. Drought Monitor report released Thursday shows the entire state is in some form of drought for the first time since the report began tracking such statistics at the beginning of 2000.
In a sense, the milestone is symbolic, as the proportion of the state's area in drought surged to 98 percent almost a year ago, on May 7, 2013, and has stayed at or above 94 percent since.
The Drought Monitor report uses a five-point rating system to designate dry conditions. The lowest level, D0, indicates "abnormally dry" but non-drought conditions. The other four categories, D1 through D4, designate various stages of drought, with D4 labeled "exceptional" – the kind of drought one would expect to occur about 2 percent of the time (e.g., 2 years out of 100) in any given location.
All categories of drought have expanded to the largest areas yet seen in the 21st century in California. The D4 category expanded into more of the San Francisco Bay Area this week, upping its share of the state's land mass to just under 25 percent, a new high in the Drought Monitor era.
In downtown San Francisco, just 12.20 inches of rain fell from July 1, 2013, through April 23, 2014, coming in 10.34 inches short of normal.
For the water year ending June 30, San Francisco would need 11.45 inches of rainfall just to catch up to normal; but the all-time record rainfall for April 24 through June 30 is just 4.08 inches set in 1953. The city by the bay would need nearly triple the previous record rainfall for that period just to finish with a normal amount of July-to-June rainfall.
The situation is similar in Los Angeles, where 8.91 inches of rain are required to finish with a normal July-to-June total, but the all-time record for April 24 through June 30 is only 3.58 inches. Fully three-quarters of the city's 6.02 inches of rain since July 1 came from a single week of heavy rainfall in late February and early March.
http://www.weather.com/news/science/environment/california-100-percent-drought-monitor-first-20140424
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