CALIFORNIANEVADA 

DROUGHT 

OUTLOOK

NOVEMBER 2018

National Integrated Drought 

Information System Drought.gov

Current Drought Conditions

The 2019 Water Year was off to a dry start in California-Nevada. According to 

the U.S. Drought Monitor, ~74% of California-Nevada is in moderate (D1) to 

extreme drought (D3) as of Dec. 4 (Fig. 1). Extreme drought (D3) conditions 

began impacting Ventura-Santa Barbara counties while D1-D2 conditions 

expanded over the Sierras and northern coastal California. Precipitation at the 

end of November into early December improved some of these conditions.

Fig 1. U.S. Drought Monitor for December 4. 

Source: http://droughtmonitor.unl.edu

Regional Drought & Climate Update

California and Nevada started the 2019 water year (Oct. 1, 2018) with precipitation totals below normal. For 

example, on November 19, much of California had < 25% percent of normal precipitation. High fuel loads and 

dry conditions combined with short term weather resulted in several major fires in California in November. 

Three atmospheric river (AR) events starting around Thanksgiving and continuing through the end of 

November brought rain and snow to California-Nevada, with the later storm reaching into southern California. 

As of the end of November (Fig. 2), some of the region remains near or below normal (northern CA-NV, southern 

Sierras), while others are above normal (central CA-NV and southern CA). Oct-Nov temperatures were above 

normal over much of the region, with some regions as high as 4-5°F above normal (Fig. 3).

Snowpack has finally started to build and, as of November 30, snow water equivalent values are above median 

over much of the Sierra Nevada and the Rockies (Fig. 4). Major California reservoirs are at or just below 

historical averages, while Lake Tahoe remains above the natural rim.

Fig. 2: Percent of normal precipitation (%) 

since start of the 2019 water year (Oct-Nov 

2018). Source: WestWide Drought Tracker

Fig. 3: Departure from normal temperature (°F) 

since start of the 2019 water year (Oct-Nov 2018). 

Source: WestWide Drought Tracker

Fig. 4: Percent NRCS 1981-2010 median 

snow water equivalent (SWE) on Nov 30. 

Source: NRCS

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Drought & Climate Outlook

• ENSO: Despite above-average ocean temperatures across 

most of the equatorial Pacific, ENSO-neutral conditions 

remain. However, forecasters are expecting the oceanatmosphere system to eventually couple. NOAA’s ENSO 

alert system status is currently an El Niño Watch, and the 

official forecast favors the formation of a weak El Niño that 

will continue through winter (~80% change) and into spring 

(55-60%). For more information, check out the NOAA ENSO 

blog.

• Temperature: Warm temperatures are favored over 

California-Nevada through early winter with > 40% chance 

of above-normal Dec-Feb temperatures, with the greatest 

chances (> 50%) over the northern part of the region (Fig. 5).

• Precipitation: Most of California and Nevada have slightly 

increased odds of above normal Dec-Feb precipitation 

(Fig. 5). However, additional forecasts show California and 

Nevada have equal chances of above, below, and normal 

Jan-Mar precipitation. At the time of the forecast, current 

drought conditions are forecasted to improve in some of 

the region. 

About this Outlook

On November 26, 2018, NIDIS and its 

partners held this webinar as part of a series 

of drought and climate outlook webinars 

designed to provide stakeholders in the 

region with timely information on current 

drought status and impacts, as well as a 

preview of current and developing climatic 

events.

A video of and presentations from this 

webinar can be accessed here: 

https://www.drought.gov/drought/

calendar/events/california-nevadadrought-climate-outlook-webinarnov-26-2018

Contributors

Julie Kalansky, CNAP/CW3E/SIO

Michelle L’Heureux, NOAA/NWS Climate

Prediction Center

Peter Fickenscher, NOAA/NWS CA-NV River

Forecast Center

Amanda Sheffield, NIDIS

Fig. 5: Temperature and precipitation probabilities 

for December 2018 to February 2019. Source: Climate 

Prediction Center. A = chances of Above Normal, 

EC = equal chances of Above, Below, or Normal, B = 

chances of Below Normal.

• CNAP Drought Tracker: The California-Nevada 

Application Program (CNAP), a NOAA RISA team, 

gathers information from tools developed by CNAP 

researchers and collaborators to provide a summary 

of the current precipitation and water resources 

throughout the region.

• The Center for Western Weather and Water Extremes 

(CW3E) at Scripps Institution of Oceanography 

provides atmospheric river event forecasts, 

interactive mapping tools, and more monitoring and 

forecasting tools.

• NOAA NWS California-Nevada River Forecast 

Center (CNRFC) provides hydrologic guidance 

for time scales from hours (flash flood guidance, 

flood forecasts, and reservoir inflows), to days 

(flood forecasts, reservoir inflows, and short-range 

ensembles), to weeks (short-range ensembles and 

water resources), to months (water resources). 

CNRFC coverage spans ~250,000 square miles, 

supporting 12 NWS weather forecast offices and 

customers with observed and forecasted 

conditions, including interactive mapping. 

Preparing Your Winter Toolbox: Tools 

presented during the November Webinar