New Drought Monitor map puts most of San Francisco Bay Area in 'extreme drought'

The latest version of the federal United States Drought Monitor map shows increasingly dire drought conditions throughout California and "extreme drought" spreading across nearly the entire San Francisco Bay Area region.

"The presence of drought on the map is no surprise — especially in Northern California," wrote Richard Heim, a meteorologist for the National Oceanic and Atmospheric Administration, who was one of the authors of this week's map. California has seen consecutive dry winters and last winter was the third driest on record.

The map classifies the level of dry conditions on a color-coded scale from "abnormally dry" (yellow) to "exceptional drought" (maroon). The April 29 map shows the most severe conditions developing along the state's southern border with Nevada and Arizona. "Extreme drought" (red) covers much of southern and northern California, and "severe drought" (orange) is spread across most of the rest of the state.

The last drought in California ran from 2012 to 2016, and at its height in 2014, all of the state — 100% — was covered by severe to exceptional drought from May 13, 2014, to July 29, 2014, and 81.92% was covered by exceptional to extreme drought from Aug. 5, 2014, to Oct. 28, 2014, Heim noted.

Today, severe to exceptional drought covers 87.95% and exceptional to extreme drought 52.86%.

"So, while it's bad now, in the recent past it has been worse," he said.

The federal government releases a new Drought Monitor map depicting drought conditions across the country every Thursday, and news organizations and Twitter users often share the latest release, with the map going viral.

With the situation worsening in California, the map has become a poster child for a looming drought as the amount of red indicating extreme drought increases every week.

While the map is a part of the story, Jeanine Jones, California's drought manager with the state's Department of Water Resources, said it's important to understand the graphic that fits onto one page doesn't provide a complete picture.

"It's the tool to serve all purposes until you look at the nuances of where your water supply comes from and it becomes more complex," she said. "While the map is probably most representative of conditions when it's very wet or very dry, it's everything in between that's more difficult to depict."

Jones noted that the map is less effective in depicting localized conditions in urban water districts, for example. "You can have two adjacent districts ... if one has a water supply dependent on surface supply, they may feel greater impacts of drought conditions than a district that's more dependent on groundwater," she said.

The Drought Monitor is a joint effort of the NOAA, the U.S. Department of Agriculture and the National Drought Mitigation Center at the University of Nebraska-Lincoln. The weekly map isn't a forecast but rather is a reflection of the precipitation from the past week.

While the map takes into account precipitation totals, it indexes a wide array of indicators, including groundwater storage, river levels, soil moisture, satellite-based assessments of vegetation health and more.

The map is a mechanism to measure drought that's mainly applied to agriculture, and the U.S. Department of Agriculture uses it for the basis of decisions about agricultural financial assistance.

"You've probably seen some of the stories talking about the USDA designating California an agricultural disaster area; what they're referring to is based on the drought monitor," explained Jones, pointing to the USDA's April 5 announcement offering low-interest loans to assist drought-impacted farmers and ranchers.