El Niño Impacts 

and Outlook

Missouri Basin Region

September 2014 

Typical El Niño Winter Pattern

Contact: Barbara Mayes Boustead (barbara.mayes@noaa.gov) Missouri Basin Region El Niño Impacts and Outlook| September 2014 

Winter Temperature and Precipitation El Niño Likely

El Niño Outlook and Climate Connections

Percent of Average Precipitation (%) 

in Winter During Past El Niños

Departure from Average Temperature (°F) 

in Winter During Past El Niños

El Niño Winter Tendencies

El Niño is a particular pattern in the Pacific 

Ocean that affects weather downstream to 

the United States. It has its most notable 

impacts in the winter, when wind patterns 

in the atmosphere are strongest. When El 

Niño is present, it provides some predictable 

effects to weather patterns. While no two 

El Niño events are alike, the typical winter 

weather pattern (left) brings the polar jet 

stream farther north than usual, across 

Canada, while the Pacific jet stream remains 

in the southern U.S. As a result, the upper 

Missouri River basin can be warmer than 

normal, with the potential for less frequent 

heavy snow than usual. Confidence in these 

patterns is higher with stronger El Niño 

events.

Odds still favor an El Niño forming by 

mid to late fall, with a 60-70% chance of 

development. There is a 30-40% chance for 

neutral conditions to continue through this 

winter, with a near-zero chance for La Niña to 

develop.

Typical El Niño jet stream patterns across the U.S. include a stronger than usual storm track across the 

southern U.S., leaving the northern U.S. removed from the average storm track. Image courtesy of 

NOAA.

Chart based on summaries and forecast model data 

from the NOAA/NWS Climate Prediction Center and 

the International Research Institute for Climate and 

Society.

Highest Potential for 

Weak to Moderate El Niño

The winter outlook from the NOAA/NWS Climate Prediction Center mainly is consistent with 

typical El Niño patterns across the central U.S., shown above, with a slightly increased chance 

for above-normal temperatures from the upper Missouri River basin. There also is a slightly 

increased chance for below-normal precipitation in Montana and Wyoming. During past El Niños, 

wet conditions have been observed across parts of the Central Plains and into the upper Missouri 

River basin. 

Departures from average temperature (left) and percent of average precipitation (right) in December 

through February during past El Niño years. Image courtesy of the Midwest Regional Climate Center.
Ongoing Conditions and Possible Impacts

El Niño Limitations and Myths Partners and Links

Great Lakes Environmental Research Laboratory

www.glerl.noaa.gov

Great Lakes Integrated Sciences + Assessments

glisa.umich.edu

High Plains Regional Climate Center

www.hprcc.unl.edu

Int’l Research Institute for Climate and Society

iri.columbia/edu/our-expertise/climate/forecasts/enso

Midwestern Regional Climate Center

mrcc.isws.illinois.edu

National Drought Mitigation Center

www.drought.unl.edu

National Integrated Drought Information

System (NIDIS)

www.drought.gov

National Oceanic and Atmospheric Administration

www.noaa.gov

National Weather Service - Central Region

www.crh.noaa.gov/crh

National Climatic Data Center

www.ncdc.noaa.gov

Climate Prediction Center

www.cpc.ncep.noaa.gov

National Operational Hydrologic Remote Sensing Center

www.nohrsc.noaa.gov

State Climatologists

www.stateclimate.org

South Dakota State University Extension

igrow.org

U.S. Department of Agriculture

www.usda.gov

NRCS National Water & Climate Center

www.wcc.nrcs.usda.gov

Regional Climate Hubs

www.usda.gov/oce/climate_change/regional_hubs.htm

Useful to Usable (U2U) 

https://drinet.hubzero.org/groups/u2u

Western Water Association 

wwa.colorado.edu

Contact: Barbara Mayes Boustead (barbara.mayes@noaa.gov) Misouri Basin Region El Niño Outlook and Impacts

Missouri River Levels

Due to a wet summer, the Missouri River is 

running higher than usual for the time of year. 

Navigation season will be extended into the 

fall to move water out of the reservoirs and 

make space. Some indicators suggest a tilt 

toward lower than usual mountain snowpack 

in the Fort Peck drainage area during El Niño, 

but the signals are weak.

Precedent Conditions

Moisture conditions through the summer of 

2014 have been near to above average across 

the upper Missouri River Basin, alleviating 

drought conditions in the mid to lower Missouri 

River valley. Areas of near to below average 

precipitation linger in eastern South Dakota and 

in Kansas and Missouri.

Growing Season Lagging

The 2014 growing season had a late start due 

to a cold spring, and it continues to lag in the 

Missouri Basin region. Even average conditions 

through the rest of the growing season would 

hamper some crops from reaching maturity. 

El Niño is not associated with the potential for 

early or late first freeze in the fall.

El Niño impacts can be limited by many factors, including:

• It may not develop.

• It may be weak, with little or no discernible influence on weather patterns.

• It may be masked by other weather and climate signals.

• Single extreme events can “buck the trend” of the averages for the rest of 

the season, with one or two high-impact events overshadowing the average 

conditions.

El Niño can affect some temperature and precipitation signals in the region, but it is not 

known to affect:

• First freeze date in the fall (either early or late).

• Last freeze date in the spring (either early or late).

• Potential for ice storms or blizzards.

• Track or intensity of any single weather system.

Risks of extreme temperatures and precipitation during moderate to strong El Niño events. Images courtesy of NOAA 

Earth Systems Research Laboratory.

Precipitation percent of normal for January 1 through August 

31, courtesy of High Plains Regional Climate Center. Growing degree day departure from average for May 1 

through September 14, courtesy of Midwestern Regional 

Climate Center.

Gavins Point Dam. Image courtesy of the U.S. Army Corps of 

Engineers.