Contacts: Doug Kluck (doug.kluck@noaa.gov)

	 Natalie Umphlett (numphlett2@unl.edu)

Missouri Basin Region La Niña Impacts and Outlook | November 2017 

https://www.drought.gov/drought/dews/missouri-river-basin

La Niña Impacts 

and Outlook

Missouri Basin Region 

November 2017 

Typical La Niña Winter Pattern

Winter Temperature and Precipitation Outlooks La Niña Evolution

Winter Outlook

Valid for December 2017 - February 2018 Through Summer 2018

La Niña in Winter

A La Niña develops when sea-surface 

temperatures in the equatorial Pacific Ocean 

are cooler than average for an extended period 

of time. This affects the location of jet streams, 

causing impacts in North America. The most 

notable impacts occur in the winter, when the 

wind patterns in the atmosphere are strongest.

The typical La Niña winter weather pattern brings 

the polar jet stream into Alaska, then plunging 

into the central and eastern U.S. This path can 

bring below-normal temperatures into the 

northern U.S., especially the northern Rockies 

across the northern Plains and into the Great 

Lakes. Meanwhile, the southern Plains often are 

left warm and dry. The Pacific jet stream tends 

to track close to the Pacific Northwest, bringing 

increased chances for moisture there. Finally, 

odds increase slightly for wetter-than-normal 

conditions in the Ohio River Valley. 

For the Missouri Basin, this typically means 

increased chances for below-normal temperatures 

in the upper Basin. Additionally, the northern 

Rockies also may have increased chances for an 

above-normal snowpack.

A La Niña was officially declared this fall; 

however, it is predicted to remain weak 

with a possible transition back to neutral 

conditions by spring. The chart above shows 

the likelihood of La Niña, El Niño, and neutral 

conditions over the next several months. 

The odds are highest for La Niña (blue bars) 

through winter, then the highest odds shift 

toward neutral (green bars) in the spring 

and summer. El Niño (red bars) chances then 

increase through the summer but remain 

relatively small. This is a typical evolution 

of the ENSO pattern. For more information, 

please see: http://iri.columbia.edu/ourexpertise/climate/forecasts/enso/current/. 

Despite the relative weakness of the current La Niña, the winter outlook largely follows a typical 

La Niña pattern for the Missouri Basin states. Above-normal precipitation is favored for areas 

of the northern Rockies, the panhandle of Nebraska, and the Dakotas. Meanwhile, increased 

chances for below-normal precipitation exist to the south of the region. For temperatures, belownormal conditions are favored to the north, while above-normal conditions could occur across 

portions of Wyoming, Colorado, and Kansas. The temperature and precipitation outlooks are 

consistent with a more active storm track across the northern half of the region this winter. Learn 

more about the limitations of this forecast on page 2.

The seasonal outlooks above combine many factors including climate models, the effects of 

long-term trends, soil moisture, and the El Niño Southern Oscillation cycle (ENSO). Because these 

outlooks combine many inputs, they do not match the typical La Niña conditions exactly. To learn 

more, or to retrieve the latest temperature, precipitation, and drought outlooks, please visit the 

Climate Prediction Center at: http://www.cpc.ncep.noaa.gov.

The image above shows the typical pattern in the winter during La Niña events. The polar jet stream 

tends to traverse right through the Missouri Basin region, making it the dividing line between cold and 

warm air masses. This means that colder conditions could be in store for areas of the upper Basin, 

while the southern Plains could be warm and dry.

Image courtesy of the National Oceanic and Atmospheric Administration.

For more information please visit: https://www.climate.gov/news-features/department/enso-blog.

Temperature Precipitation

EC: Equal chances of above, near or below normal, A: Above normal, B: Below normal

Early Nov CPC/IRI Official 

Probabilistic ENSO Forecast
Potential Winter and Spring Impacts

Contacts: Doug Kluck (doug.kluck@noaa.gov)

	 Natalie Umphlett (numphlett2@unl.edu)

Missouri Basin Region La Niña Impacts and Outlook | November 2017 

https://www.drought.gov/drought/dews/missouri-river-basin

Comparisons and Limitations Missouri Basin Partners

High Plains Regional Climate Center

www.hprcc.unl.edu

International Research Institute for Climate and 

Society

http://iri.columbia.edu

National Drought Mitigation Center

www.drought.unl.edu

National Integrated Drought Information System

www.drought.gov

National Oceanic and Atmospheric Administration

National Weather Service - Central Region

www.crh.noaa.gov/crh

National Centers for Environmental Information

www.ncdc.noaa.gov

Climate Prediction Center

www.cpc.ncep.noaa.gov

American Association of State Climatologists

www.stateclimate.org

U.S. Army Corps of Engineers - Missouri River Basin 

Water Management Division

www.usace.army.mil

U.S. Department of Agriculture - Climate Hubs

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

No Two La Niñas are the Same

The images above show the overall conditions from the last weak wintertime La Niña event of 2000-2001. Although the below-normal 

temperatures align well with a typical La Niña winter, the precipitation pattern was quite different, with dry conditions across Montana and wet 

conditions across the central and southern Plains. Because no two La Niña events are alike, it is important to note that there are limits to the 

predictability of La Niña impacts this winter. Short term climatic influences that are not predictable beyond a week or two can play havoc with the 

seasonal forecasts and can overshadow the “typical” La Niña pattern. Even the strength of the La Niña (weak vs. strong) has an influence on whether 

temperatures will be above- or below-normal in some cases. 

Sunset over Holmes Lake in Nebraska.

Image courtesy of Natalie Umphlett.

Agriculture Missouri River Economy

The Missouri River Mainstem Reservoir 

System is well positioned for the 2018 runoff 

season. The 2017 runoff for the upper Basin is 

expected to be slightly above average (115% of 

long-term average). Over the winter, the U.S. 

Army Corps of Engineers will be evacuating 

the remaining stored flood waters. The 2018 

runoff season will begin with full conservation 

storage, while having all the 16.3 million 

acre feet of flood control storage available 

to capture runoff from mountain and Plains 

snowmelt and rainfall events this spring and 

summer. The full conservation pool will allow 

for full support for all authorized purposes that 

require water flowing though the dams, such 

as navigation and downstream water supply. 

Feeding time in Osage, Wyoming.

Image courtesy of ©Brittany Hamilton.

Train in Holdrege, Nebraska.

Image courtesy of Ken Dewey.

La Niña conditions can have worldwide 

impacts to the agricultural sector. Here in 

the Missouri River Basin region, drought 

conditions, which emerged in the late 

spring and early summer, are proving to be 

a challenge for winter wheat, particularly in 

areas of the Dakotas. However, wetter soils in 

areas of central Montana, western Wyoming, 

eastern Colorado, western Kansas, eastern 

South Dakota, and much of Nebraska will be 

beneficial for spring planting and forage growth 

next year. Other potential concerns include the 

overwintering of pests due to warm conditions 

in southern areas, and calving/lambing issues 

due to cold conditions in northern areas. 

La Niña conditions can have impacts to a 

wide variety of sectors. Although losses occur 

regardless of the ENSO phase, according to 

insurance data, on average, La Niña events 

tend to result in the largest economic losses 

worldwide. For the Missouri River Basin, there 

could be both positive and negative impacts to 

the economy. For instance, northern areas of 

the Plains expecting a cold and snowy winter 

could have increased costs for home heating 

and snow removal, in addition to potential 

difficulties related to travel. In areas of the 

northern Rockies, however, an increased 

snowpack could be welcomed by ski resorts 

and outdoor enthusiasts.

Departure from mean temperature (left) and percent of mean precipitation (right) during the La Niña winter 

of 2000-2001. Maps courtesy of the Midwestern Regional Climate Center.

La Niña impacts can be limited by many factors, including:

• 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.

La Niña 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.