La Niña Impacts 

and Outlook

Missouri River Basin

November 2021

Typical La Niña Winter Pattern 

The image (source: NOAA) above shows the typical pattern in the winter 

during La Niña events. The polar jet stream tends to transverse through 

the Missouri Basin, 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 Basin and the Plains could be warm and dry.

Highlights for the Basin

A La Niña develops when sea surface 

temperatures in the eastern equatorial 

Pacific are consistently cooler than 

average for an extended period of time. 

These cool waters affect the location of 

the jet streams, which impacts weather in 

North America. The most notable impacts 

occur in winter.

While no two La Niña events are alike, 

there are some general patterns that 

are predictable. For instance, the polar 

jet stream is typically further south than 

usual during La Niña winters.

For the Missouri River Basin states, the 

typical winter La Niña pattern leads to 

increased chances for below-normal 

temperatures across the upper Basin. The 

northern Rockies may also have increased 

chances for above-normal snowpack. 

La Niña Outlook 

Winter Temperature and Precipitation Outlooks 

Valid for December 2021 - February 2022

Temperature Precipitation

 As of mid-October, NOAA’s Climate Prediction Center outlooks largely follow a typical La Niña pattern for the Missouri 

River Basin. Generally, the region has increased chances for cooler (blue), wetter (green) conditions across the north, 

and warmer (orange), drier (tan) conditions across the south. Below-normal temperatures are likely in Montana and 

portions of the Dakotas and Wyoming, while above-normal temperatures are likely across Colorado, Kansas. Abovenormal precipitation is likely across much of Montana and Wyoming, while below-normal precipitation is likely in 

southern Colorado and Kansas. Much of the region, including the Dakotas, Nebraska, Kansas, western Montana and 

Wyoming, and Northern Colorado, are likely to observe equal chances of above-, below-, and near-normal precipitation. 

La Niña conditions have continued this fall and forecasts indicate that this La Niña will strengthen, peaking as a 

moderate or even strong event in late fall or early winter. According to the Climate Prediction Center, there is an 87% 

chance that these conditions will last through the winter and about a 60% chance that La Niña will continue into the 

early spring. A La Niña Advisory is currently in effect.

Missouri Basin Region El Niño Impacts and Outlook | November 2021 

https://www.drought.gov/drought/resources/reports

Contact: Heleena Pettee (Hpettee2@unl.edu)

Doug Kluck (doug.kluck@noaa.gov)
Potential Winter and Spring Impacts

Changes to normal snowfall patterns for La 

Niña. Blue indicates above normal snowfall.

Ice over Missouri River in ND. Photo 

courtesy: Michael Swenson.

Missouri River 

According to the U.S. Army Corps of Engineers, the 2021 runoff forecast 

for the upper Basin is 15.0 MAF, which is more than 10 MAF below 

normal. Widespread drought conditions have impacted streamflow and 

reservoir inflows in certain areas this summer and fall. Even with recent 

above normal precipitation, it may not lead to increased runoff due to 

drier-than-normal soils in areas. According to the U.S. Army Corps of 

Engineers releases from Gavins Point Dam will be reduced to winter rates 

starting on November 22. Economy 

For the Missouri Basin, impacts in the region could be mixed. For instance, 

northern areas expecting a cold snowy winter could have increased costs 

for heating and snow removal, in addition to travel difficulties. However, 

an increased snowpack in the northern Rockies could be welcomed by ski 

resorts and other outdoor enthusiasts. 

Agriculture

In the Missouri Basin, widespread drought conditions have contributed to 

the fall harvest progressing quickly. However, dry conditions could be an 

issue for winter wheat if timely rains do not materialize. Winter outlooks 

from NOAA for November through February are leaning slightly towards 

above-normal precipitation in northwest Wyoming and much of Montana, 

with higher chances in western Montana, which could help to begin 

mitigating drought there. Across the region, concerns for the winter may 

include calving/lambing issues due to cold conditions in northern areas, and 

the overwintering of pests due to warm conditions in southern areas.

Comparisons and Limitations

Winter Conditions of Past La Niñas

 January - March 2021

Maps courtesy: Midwestern Regional Climate Center

The maps above show the winter conditions of the most recent La Niña 

event last winter in 2020-2021. Most of the Basin was cooler (as shown in 

green) than average. While precipitation varied in the region, the highest 

amounts were seen not in the northwestern portion of the Missouri River 

Basin, but in Nebraska, Kansas, and portions of Colorado. This most recent

La Niña did not conform to expectations which goes to show that no two La Niña events are the same. As a result, 

it is important to note that there are limits to the predictability of impacts this winter, and other factors should be 

considered. For instance, in the Missouri Basin, La Niña is not known to predict: 1) first freeze in the fall, 2) last freeze 

in the spring, 3) potential for ice storms or blizzards, 4) track or intensity of any single weather system, or 5) potential 

for drought/flooding in the spring.

MO River Basin Partners

https://www.usbr.gov/

USDA Northern Plains Climate Hub 

www.climatehubs.oce.usda.gov

Contact: Heleena Pettee (Hpettee2@unl.edu)

Doug Kluck (doug.kluck@noaa.gov)

Missouri Basin Region El Niño Impacts and Outlook | November 2021 

https://www.drought.gov/drought/resources/reports

High Plains Regional Climate Center 

www.hprcc.unl.edu

National Drought Mitigation Center 

http://drought.unl.edu/

National Integrated Drought Information System 

https://www.drought.gov/

NOAA NCEI 

www.ncdc.noaa.gov

NOAA NWS - Central Region 

www.weather.gov/crh

NOAA NWS Climate Prediction Center

www.cpc.ncep.noaa.gov

NOAA NWS Missouri Basin River Forecast Center 

www.weather.gov/mbrfc 

American Association of State Climatologists 

https://www.stateclimate.org/

U.S. Army Corps of Engineers 

www.nwd-mr.usace.army.mil/rcc/

U.S. Bureau of Reclamation