Near to above normal precipitation accumulations observed during the Water Year (Oct 1-Sept 30) 2016 to-date eased drought conditions in some parts of California and Nevada. However, a combination of near-average Sierra snowpack, above normal temperatures, below expected precipitation accumulations in southern California with a strong ENSO, and lingering drought impacts have allowed drought to persist in the region. As of July 19, 2016, 83.59% of California and 34.25% of Nevada, were observing drought conditions according to the U.S. Drought Monitor (figure 1). This is an improvement to this time last year, where 97.35% of California and 97.78% of Nevada were in drought. The current D3-D4 percent area has decreased to levels not seen since late 2013-early 2014 (figure 2). However, long term extreme to exceptional drought and long term impacts remain in areas of southern California, south Central Coast, southern Central Valley, and southern Sierras. The USDM provides a way to track drought in our region, and this post addresses the questions: What is the U.S. Drought Monitor? How does it work?
The U.S. Drought Monitor (USDM) began in 1999 and is a collaborative effort between the National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln, the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Department of Agriculture (USDA). Every Thursday, they release a USDM map that is used by state, local, and basin-level decision makers to trigger drought response, as well as by the USDA.
What is shown on a USDM map?
The map shows the drought intensity for whatever geographic region is selected. On the USDM Website you can select the US as a whole, or select a state or watershed. This CA-NV version is provided for the regional California-Nevada Drought Early Warning System (DEWS). In the upper right corner, the cutoff date for data is shown (here, July 19th) followed by the date the map was released (here, July 21st). Below that, you can find the percent of area in the selected region in each drought category and the USDM color classification scheme of drought intensity, followed by the USDM author and partners.
What is the USDM Classification Scheme?
The yellow to red colors represent the classification of drought intensity. The USDM uses five classifications: D0 Abnormally Dry, D1 Moderate Drought, D2 Severe Drought, D3 Extreme Drought, and D4 Exceptional Drought. Additionally, on some versions of the USDM (such as the national map), black lines define areas of short- (S = past 6 months) and long-term (L = 6+ months) drought impacts.
How are the USDM Categories determined?
There are 13 USDM authors from NDMC, NOAA (NCEI, CPC, WRCC), and USDA. Each week, the Drought Monitor author compiles a variety of information and input from local and regional experts and observers to localize the information as much as possible. Inputs they consider are drought indices and other climatological inputs, satellite observations of vegetation health, and other observations and models of soil moisture and hydrologic data such as snowpack. The map draft goes through multiple iterations each week, taking in more input from observers from emails, state and regional-level drought conference calls, and other helpful contacts. More information on the classification scheme inputs can be found here. The USDM focuses on broad-scale conditions assessing drought down to the county level, and local conditions may vary.
How can I stay up-to-date on the USDM?
Current and archived USDM maps can be found at the USDM, while a CA-NV regional map can be found at the California-Nevada Drought Early Warning System (DEWS).
How can I get involved in the USDM process?
March 10, 2016
CNAP researchers contributed data and information to San Diego PBS affiliate KPBS announcing local conditions would fall short of the precipitation necessary to break the California drought.
DATA SOURCES for above graphic: Rainfall data comes from a weighted average of 96 weather stations throughout the state. Snowpack data represents the average of three different multi-station measures of the northern, central and southern Sierra snowpack. Scripps Institution of Oceanography researchers, through the California Nevada Applications Program RISA and the Center for Western Weather and Water Extremes, helped compile the data.
CNAP researcher Dan Cayan is quoted in the article:
Scripps Institution of Oceanography climate researcher Dan Cayan, who helped compile data for the KPBS Drought Tracker, said to truly put a dent in the drought, those numbers would have to hit 150 percent by April 1.
“We’re probably not going to see 150 percent,” Cayan said. “Which is at the upper end of the precipitation that might’ve been expected even in a heavy year.”
On January 22, 2016, CNAP hosted a Winter Status Update featuring presentations from key experts. Over 30 participants from city, local and state governments, universities, tribal, non-profit organizations, water districts and other research agencies attending this day-long update on issues relevant to the current water year. CNAP researcher Dr. Kelly Redmond opened the meeting with a regional winter weather and climate update. Dr. Mike Dettinger (USGS, CNAP) followed with a look at the current water storage including snowpack and reservoir information. After lunch CNAP affiliated researcher Dr. F. Martin Ralph discussed observations and forecasting of atmospheric river events. CNAP researcher Dr. Shraddhanand Shukla followed this with a look at multi-model precipitation forecasts. The El Niño/Southern Oscillation Forecast discussion by CNAP researcher Dr. David Pierce (pictured above) wrapped up the presentations. Lively discussions were held prior to and during lunch as well as before the closing of the meeting. To view presentations from this meeting please click here.
The California Department of Water Resources (DWR) has released a YouTube video about groundwater sustainability. The DWR Groundwater Sustainability Plan (GSP) Emergency Regulations Draft is presented by the DWR Sustainable Groundwater Management Program. This information meeting webcast (almost two hours) covers
a selection (batch 3) of topics that are being discussed and considered for the draft of the emergency regulations for groundwater sustainability. This video gives interesting background about groundwater budget (total accounting of groundwater, surface water entering and leaving a basin as well as the water stored). In addition groundwater management as far as data collection and understanding about groundwater is emphasized. These topics are explored as pertains to the development of this plan. Please find the video at:
The spring Great Basin Climate Forum will be held on April 8, 2015, at the Desert Research Institute in Reno, NV. The topic of this spring’s meeting is: “What can we learn from the last 4 years of drought?”. This forum offers presentations in a conversational format and is intended to be of primary interest to public and private resource managers and professionals, tribal members and NGOs. The following speakers and presentation titles are planned:
- Winter 2014-15 Climate And Hydro Recap, Present Conditions, Spring & Summer Outlooks – Kelly Redmond, Regional Climatologist, Western Regional Climate Center/DRI
- Air Pollution Increases Forest Susceptibility to Wildfire – Nancy Grulke, Director of the Western Wildlands Environmental Threat Assessment Center, USFS.
- Drought and Forest Health in the Great Basin and Eastern Sierra – Peter Weisberg, Associate Professor, Dept. Natural Resources and Environmental Science, UNR
- Can We Squeeze Climate Adaptation into a Natural Resource Manager’s Cramped Decision Space? – Mark Brunson, Professor, Dept. of Environment and Society, Utah State University
- The Role of Energy in a Sustainable Water Future – Kristen Averyt, Associate Director for Science, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
Attendance and lunch are free but registration is required. Please find more information and a registration form at: