NATIONAL INTEGRATED DROUGHT INFORMATION SYSTEM

CALIFORNIA-NEVADA 

DROUGHT OUTLOOK JANUARY 2017 

CURRENT CONDITIONS

Drought conditions have improved greatly in California and 

Nevada, with removal of drought in parts of Nevada and Northern 

California and slower, albeit notable, drought reduction in 

Southern California. Much of this improvement has been since 

January 1, 2017, with widespread one to three class improvements 

in the past 4 weeks. As of January 24, only 51.4% of California 

and 5.93% of Nevada remain in moderate to exceptional drought 

according to the U.S. Drought Monitor (USDM) (compared to 

97.17% and 73.26% at this time last year, respectively).

These improvements are due to near and above normal 

precipitation region-wide. Since the beginning of the 2017 water 

year (WY 2017) precipitation totals across both states are above 

normal, with much of the region receiving over 200% of normal 

January precipitation. These marked improvements are in large 

part the result of several large (and frequent) precipitation events 

called atmospheric rivers, in January. Atmospheric rivers(ARs) 

are narrow corridors of high water vapor transport in the lowest 

2 km of the atmosphere. ARs can produce abundant and often 

intense rainfall and are especially important in California because 

they can boost rainfall totals (especially important for the 

replenishment of rain-fed reservoirs, surface water supplies and 

groundwater aquifers) but can also result in natural hazards such 

as flooding, intense runoff and landslides.

 Snow drought, an increasingly common occurrence in the West 

in recent years, is a result of above average temperatures causing 

precipitation that would normally be expected to fall as snow to 

occur instead as rain. The most basic definition of snow drought 

is above normal precipitation accumulation and below normal 

snow water equivalent (SWE) occurring at the same time. This can 

result in diminished snow accumulation and increased, or early 

runoff. In late 2016, the Sierra Nevada snowpack in California was 

66% of normal, despite above normal precipitation from several 

ARs, due to above normal temperatures during storms resulting in 

temporary snow drought conditions. However, continuous storms 

through mid-January 2017 brought heavy snowfall and lower 

snow levels and resulted in greatly improved regional snowpack. 

As of January 19, SWE observations are above normal for this time 

of year. Nevada SNOTEL sites show 125% to greater than 200% 

above normal for this time of year, while California Department of 

Water Resources (CA DWR) north, central, and south automated 

snow sensors in the Sierra Nevada are at 145%, 175%, and 203% of 

normal, respectively.

Currently California’s snowpack is 108% of the April 1st 

normal and many reservoirs in Northern California are near or 

above historical normals with some nearing flood control release 

% NORMAL PRECIPITATION

WATER YEAR THROUGH JAN. 29, 2017

(OCT. 1, 2016 - JAN. 29, 2017)

http://droughtmonitor.unl.edu/

U.S. DROUGHT MONITOR 

CLASS CHANGE: 

JAN. 3 - JAN. 24, 2017

No change

1 Class improvement

2 Class improvement

3 Class improvement

4 Class improvement

U.S. DROUGHT MONITOR 

FOR JAN. 24, 2017

U.S. DROUGHT MONITOR 

FOR JAN. 3, 2017

Drought intensity

D0: Abnormally dry

D1: Moderate drought

D2: Severe drought

D3: Extreme drought

D4: Exceptional drought
levels. Reservoir levels are very important 

for California’s water supply, but many 

regions (including the Central Valley) are 

groundwater dependent and even with 

January’s above normal precipitation 

groundwater conditions have not yet 

stabilized or are unknown. Although 

drought conditions are much improved, 

cautious optimizing is advised. Warm and 

dry conditions between now and April 

1st 2017 could result in early melting and 

sublimated snowpack potentially setting 

the stage for continued drought conditions 

throughout the rest of the year.

FLOODING IN TIMES OF 

DROUGHT

 Recent intense storm events can help 

alleviate drought impacts, but can also 

cause flooding. As a result, a region may 

be dealing with drought and flooding 

events simultaneously. While it is true 

that many parts of California have 

seen extreme amounts of precipitation 

in recent months, resulting in vastly 

improved drought conditions, Southern 

California has not experienced the same 

level of improvements. Through midJanuary, much of Southern California was 

still classified as Extreme to Exceptional 

Drought (D3-D4) while under flood 

watches and warnings, including San 

Luis Obispo, Santa Barbara, Ventura, Los 

Angeles, Orange and San Diego counties. 

While rain and snowpack totals are 

key inputs in the USDM decision making 

process, the USDM also takes into account 

a variety of factors including, but not 

limited to reservoir storage, surface and 

groundwater conditions, and range and 

forestland health. If Southern California 

continues to receive precipitation 

throughout the coming months, the USDM 

will be updated to reflect these improved 

water supply, soil moisture and other 

conditions important for measuring the 

severity of drought.

Even though recent precipitation in 

Southern California is beginning to help 

ameliorate drought conditions in the 

region locally, there are still tremendous 

deficits remaining, especially in local 

reservoirs and groundwater supplies. One 

of the best examples of this remaining 

deficit is Lake Cachuma, a rain-fed 

reservoir that supplies approximately 40% 

of Santa Barbara’s drinking water, and is 

currently only at 13% of normal (according 

to the CA-NV River Forecast Center 

Summary). 

CLIMATE OUTLOOK

Over this past fall into early winter, 

equatorial sea surface temperatures 

(SST) cooled and reached weak La Niña 

conditions in the tropical Pacific Ocean 

and currently La Niña conditions are 

present. This means that equatorial (Niño 

3.4 region) SSTs during the last 4 weeks 

were below average in the central and 

east-central Pacific Ocean. As of January 

19, NOAA’s Climate Prediction Center 

(CPC) has issued a La Niña Advisory. Most 

multi-model averages favor continuing 

weak La Niña conditions through the 

Northern Hemisphere with a transition 

to ENSO neutral conditions by February 

2017. Early forecasts favor ENSO-neutral 

through mid-2017 with a chance of El Niño 

(~35%) or La Niña (~15%) developing by 

August-September-October 2017.

The CPC Seasonal Outlooks as 

of January 19th show equal chances of 

above, below, and average temperatures 

and precipitation in February-March-April 

in California and Nevada. This pattern is 

forecasted to continue through much of 

spring with a slight favoring in the odds 

of above normal temperatures in southern 

California and southern Nevada and drying 

of northern California and northwestern 

Nevada. Through the end of April, 

drought is expected to persist in the far 

southern portion of California with areas 

of southern and central California and 

southwestern Nevada forecasted to remain 

in drought but improving and drought 

removal likely. High uncertainty remains. 

For shorter term forecasts, please see the 

8-14 day outlooks provided by your local 

NWS office or CPC.

OUTLOOK: PRECIPITATION

FEB-MAR-APR MAY-JUN-JULY

http://www.cpc.ncep.noaa.gov/

OUTLOOK: TEMPERATURE

FEB-MAR-APR MAY-JUN-JULY

ABOUT THIS OUTLOOK

On January 23, 2017 NIDIS and its partners 

held a California-Nevada DEWS Drought & 

Climate Outlook Webinar as part of a series 

of regular drought and climate outlook 

webinars designed to provide stakeholders 

and other interested parties in the region 

with timely information on current drought 

status and impacts, as well as a preview of 

current and developing climatic events like 

La Niña.

A video of and presentations from this 

webinar can be accessed here:

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

events/ca-nv-drought-climate-outlookwebinar-jan-23

CONTRIBUTORS

Daniel McEvoy, WRCC/DRI

Cindy Matthews, NWS WFO Sacramento

Tim Bardsley, NWS WFO Reno

Andrea Bair, NWS Western Regional 

Headquarters 

Ben Hatchett, DRI

Amanda Sheffield, SIO/UCSD

Alicia Marrs, NOAA/NIDIS