NATIONAL INTEGRATED DROUGHT INFORMATION SYSTEM

CALIFORNIA-NEVADA 

DROUGHT OUTLOOK MARCH 2017 

% NORMAL PRECIPITATION

OCTOBER 2016- FEB 2017

U.S. DROUGHT MONITOR 

CLASS CHANGE: DEC. 28 -MARCH 28

U.S. DROUGHT MONITOR 

FOR MARCH 28, 2017

Drought intensity

D0: Abnormally dry

D1: Moderate drought

D2: Severe drought

For more details and up-to-date water storage tracking in California, visit: https://scripps.ucsd.edu/programs/cnap/

water-storage-tracking-in-california/

No change

1 Class improvement

2 Class improvement

3 Class improvement

4 Class improvement

5 Class improvement

http://droughtmonitor.unl.edu/

CURRENT CONDITIONS

Drought conditions in CaliforniaNevada have continued to improve 

through late winter to early spring. Since 

January, much of central to southern 

California and Nevada have seen one to 

three class improvements, according to 

the U.S. Drought Monitor. As of March 

28, only 8.24% of California and none of 

Nevada remain in moderate to exceptional 

drought according to the USDM, compared 

to 68.9% and 33.6% three months ago, 

respectively.

These improvements are due to aboveto much-above-normal precipitation 

across almost all of California-Nevada. In 

both states, statewide precipitation since 

October 1st (a water year calendar is from 

October 1st to September 30th) has been 

the wettest on record. 

These marked improvements result 

in part from continued landfall of large 

precipitation events called atmospheric 

rivers. Atmospheric rivers (ARs) are narrow 

corridors of high water vapor transport 

in the lower 2 km of the atmosphere. 

According to the Center for Western 

Weather and Water Extremes (CW3E) 

at Scripps Institution of Oceanography, 

more than 30 ARs have made landfall 

over California with some extending 

into Nevada during the 2017 water year. 

This number is approximately double the 

average number of ARs in a water year. 

March has been relatively dry compared to 

January and February due to fewer and less 

intense AR events. 

APRIL 1 SNOWPACK

 While this water year has brought 

record-breaking precipitation to the 

region, the same cannot be said for recordbreaking snowpack. Snowpack is above 

average in California and Nevada, however 

the Sierra Nevada’s snow water content 

is less than in 1982-1983 (i.e. maximum 

observed snowpack). This is due to above 

normal temperatures in most of California 

and Nevada and high storm snow levels. 

As of March 26th, Nevada SNOTEL sites 

range between 107% to greater than 

210% of normal snow water equivalent 

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 146%, 

174%, and 165% of normal, respectively. 
Early March’s lack of storms and warm 

temperatures saw a reduction in the 

percent of April 1st average snowpack, 

with a slight rebound at the end of March. 

This loss of snow was most noticeable in 

the southern Sierras. Correspondingly, the 

southern Sierra basins snowmelt runoff 

forecasts for April-July have decreased 

the most since March 1st compared to the 

north and central basins.

Many reservoirs in California are near or 

above historical normal levels, with some 

near or above flood control release levels 

before the additional summer snowmelt. 

Forecasts of April-July unimpaired 

snowmelt runoff are greater than 100% of 

normal across the region, with potential 

higher in the eastern Sierra and Nevada 

(>200% in some basins). For example, Lake 

Tahoe will fill this summer. This will be the 

largest single-season rise in Lake Tahoe 

since records began, and currently releases 

(rare for this time of year) are being made 

to the Truckee River to avoid overflow. 

Uncertainty remains in groundwater 

recovery.

CLIMATE OUTLOOK

Over this past fall into early winter, 

equatorial sea surface temperatures 

(SST) cooled and reached weak La Niña 

conditions before transitioning to nearaverage SSTs in the central/east-central 

tropical Pacific Ocean in January-February, 

as a region of above-average SSTs 

expanded in the eastern Pacific. Currently 

ENSO-neutral conditions are present, 

favored to continue through spring 2017 

with increasing chances of El Niño (>50%) 

developing by August-September-October 

2017.

The CPC seasonal outlooks (figures 

at right) as of March 16th show equal 

chances of above, below, and average 

precipitation in April-May-June and 

July-August-September in CaliforniaNevada. Above-normal temperatures 

are favored in eastern Nevada and 

southeastern California through spring, 

with above normal temperatures 

forecasted throughout the entire region in 

summer. According to the North American 

Multi-Model Ensemble (NMME), these 

temperatures could be 0.25-0.5 ̊C above 

normal in spring in eastern Nevada and 

southeastern California, and be 0.25-1 ̊C 

above normal throughout the region in 

summer. These warm temperatures could 

affect the rate of snowmelt and runoff as 

well as evaporative demand. Experimental 

evaporative demand forecasts (function 

of temperature, humidity, wind, solar 

radiation) show risk of anomalous 

evaporative demand in northern California 

and parts of southern California in June 

and July 2017. Through June, drought is 

expected to persist in the southern central 

Californian coast as well as near the 

southern California-Arizona border. 

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

ABOUT THIS OUTLOOK

On March 27, 2017 NIDIS and its partners held a CaliforniaNevada 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/california-nevada-drought-climateoutlook-webinar-march-27

CLIMATE ENGINE

From the Desert Research Institute, the University of Idaho, Google, 

and NIDIS, Climate Engine is an on-demand tool for cloud computing and 

visualization of climate and remote sensing data. Visit climateengine.org to 

analyze and interact with climate and land-surface environmental monitoring 

datasets in real-time to improve decision making related to drought, water 

sustainability, agricultural productivity, wildfire, and ecological health. 

The image shows MODIS observed NDVI % difference from average from 

Climate Engine. Higher than average precipitation has resulted in greener 

than normal conditions across much of the west. For example, you can see the 

super bloom occurring in the Anza-Borrego Desert State Park. However, this 

condition could change quickly during the growing season for shallow rooted 

plants if little precipitation occurs. While increased precipitation and runoff this 

season is great for rivers and streams, impacts on vegetation is dependent on 

type of vegetation (crop versus grass/shrub/tree), rooting depths, and water 

sources (surface versus groundwater). For example, grasses have shallow roots 

while alfalfa crop has a deep root depth. Differences in root depth and soil 

water holding capacity (i.e. plant available water) cause differences in drought 

tolerance and response. 

CONTRIBUTORS

Daniel McEvoy, WRCC/DRI

Julie Kalansky, CNAP/CW3E/SIO/

UCSD

Justin Huntington, WRCC/DRI

Amanda Sheffield, CNAP/SIO/

UCSD

“EC” means equal chances of above- or below-normal

“A” means above-normal chances

OUTLOOKS

TEMPERATURE

APR-MAY-JUNE JULY-AUG-SEPT

33%-40% 40%-50% 50%-60%

PRECIPITATION

APR-MAY-JUNE JULY-AUG-SEPT

33%-40% 40%-50%

PHOTO BY SHAI KALANSKY