Great Lakes Region

La Niña Impacts| November 2016 

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

Great Lakes

November 2016

La Niña Impacts 

and Outlook

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. 

While no two La Niña events are alike, the typical winter 

weather pattern (image) brings the polar jet stream into Alaska, 

then plunges into the central and eastern United States. This 

path can bring colder-than-normal temperatures into the 

northern United States, especially the northern Rockies across 

the northern plains and into the Great Lakes. Meanwhile, the 

southern Great Plains often are left warm and dry. The Pacific 

jet stream tends to track closely along the Pacific Northwest, 

bringing increased chances for moisture. Finally, odds increase 

slightly for wetter-than-normal conditions in the Ohio River valley.

The result for the Great Lakes is that odds shift toward chances 

to be cooler than normal, especially in the western Great Lakes 

area. The southern Great Lakes, near the Ohio River valley, also 

may see a slight shift toward wetter-than-normal conditions. 

Finally, there is evidence that weak La Niñas favor more ice cover 

especially when coupled with other large-scale climate influences 

that are only predictable on much shorter time scales.

Typical La Niña Winter Pattern

Winter Outlook

Precipitation and Temperature Maps La Niña Evolution

La Niña in the Winter

Typical impacts of La Niña on U.S. winter temperature and precipitation. Such impacts 

have been associated with past episodes, but all impacts aren't seen with every episode. 

NOAA Climate.gov drawing by Fiona Martin. (Image Source: NOAA Climate.gov) For more 

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

Despite the relative weakness of the La Niña, the winter outlook from the 

Climate Prediction Center largely follows typical La Niña patterns for the Great 

Lakes. The Great Lakes straddles the boundary of temperature conditions, with 

slightly increased chances for colder temperatures in the western lakes and 

equal chances for above-, below-, or neutral temperatures across the eastern 

lakes. Note that these chances are quite small because of uncertainty in the 

strength and position of the La Niña as well as other potential influences.

For precipitation, the outlook indicates slightly greater chances for wetterthan-normal conditions over the Great Lakes and surrounding areas. 

The temperature and precipitation outlooks are consistent with a more active 

storm track across the region this winter, leading to more cold outbreaks and 

precipitation chances. The outlook is complicated by the likely weakness of the 

La Niña, as well as the potential for other climate effects (such as the Arctic 

Oscillation) to play a larger role from time to time. These other influences can 

overwhelm the La Niña pattern and are much more difficult to forecast this 

far in advance. The La Niña impacts will likely reach their climax during winter 

and then slowly ebb as spring approaches. Please visit the Climate Prediction 

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

La Niña conditions were officially declared in the fall of 2016. 

Conditions strengthened enough to reach a weak La Niña phase as 

predicted when the sea surface temperature anomalies surpassed 

−0.5°C on the Oceanic Niño Index (ONI). This La Niña episode is not 

predicted to last very long and the equatorial Pacific Ocean may 

revert back to a neutral condition later in the winter. The bar chart 

shows the likelihood of La Niña, El Niño, and neutral conditions over 

the upcoming seasons. The odds are highest for La Niña (blue bars) 

through winter but decreasing. The highest odds shift toward neutral 

(green bars) in early spring through the summer months. El Niño 

(red bars) chances increase through the summer as well but remain 

relatively small. This is a typical evolution of the ENSO pattern. For 

more information please visit:

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

/current/

Temperature Valid for Dec 

2016–Feb 2017

EC: Equal chances 

for above-, 

below-, or nearnormal

A: Above normal

B: Below normal

Precipitation
Contact: Doug Kluck (doug.kluck@noaa.gov) Great Lakes Region

La Niña Impacts | November 2016

Climate Impacts

Agriculture

La Niña has worldwide impacts on the 

agricultural sector. For the Great Lakes, most of 

the impacts are felt in winter. Winters associated 

with La Niña tend to be cold with above-average 

precipitation and could negatively impact winter 

wheat and fruit orchards. However, because 

La Niña winters typically result in increased 

snowpack in the Great Lakes, this could insulate 

these crops to the cold air outbreaks and harsh 

wind. Harsher winter temperatures could be 

negative for livestock producers due to increased 

operating costs and potential stress on animals. 

La Niña could affect commodity prices due to 

negative impacts internationally.

Economic

Cold and wet winters with above-average 

snowfall can have sector-specific impacts on 

the economy. The largest negative impacts 

associated with La Niña are increases in 

home heating costs, costs associated with 

snow removal, and difficulties in overland 

transportation. Sectors that depend on normal 

winter weather will likely see a benefit from 

increased snowfall. These include winter 

recreation, snow removal businesses, towing 

companies, and road salt sales. In addition, 

more ice on the Great Lakes could mean the 

potential exists for a delayed navigation season 

for shipping in the spring.

No Two La Niñas Are the Same

In the images below are the differences from normal in the last weak La Niña event from the winter of 2000–2001 (December–February). In many ways 

the cooler than normal temperatures and mainly wetter conditions across much of the Midwest and Great Lakes is typical. There is no guarantee this or 

anything close to it will be the pattern this year. There are limits to our predictability of La Niña impacts this winter. As mentioned previously, 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 versus strong) has an influence on whether temperatures will be cold or warm in some cases. Below are 

some additional common limiting factors:

• It may not fully develop and thus not influence the weather as much.

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

• It may be overcome by other weather and climate events which dampen the impacts.

• One or two extreme events can cause the average precipitation or temperature for the winter to 

appear differently than the rest of the season.

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.

• Necessarily lead to drought or flooding events in the spring.

Water Levels and Lake Ice

Below-average temperatures could lead to increased 

snowpack accumulation due to high evaporation 

rates off the lakes. This means there is a better 

chance for increased runoff into the lakes during the 

spring, when runoff is typically a major contributor to 

increasing water levels. Later in the winter however 

with potentially more ice on the lakes due to cooler 

than normal conditions would lead to less evaporation 

compared to a winter when the lakes are mostly ice 

free. Increased runoff and decreased evaporation 

could act to take less water away from the system than 

normal. These combined factors could lead to higher 

lake levels into next season. Finally, with the increase in 

chances for above normal precipitation the likelihood 

of greater snow accumulations are greater as well. 

National Oceanic and Atmospheric Administration

www.noaa.gov 

National Centers for Environmental Information

www.ncei.noaa.gov

Great Lakes Environmental Research Laboratory

www.glerl.noaa.gov

Climate Prediction Center

www.cpc.noaa.gov 

Office for Coastal Management

http://coast.noaa.gov/ 

NOAA Great Lakes Sea Grant Network

www.seagrant.noaa.gov 

Great Lakes Integrated Sciences & Assessments

www.glisa.umich.edu 

U.S. Army Corps of Engineers, Detroit District

www.lre.usace.army.mil 

American Association of State Climatologists

www.stateclimate.org 

National Integrated Drought Information System

www.drought.gov

Midwestern Regional Climate Center

http://mrcc.isws.illinois.edu 

USDA Midwest Climate Hub 

http://www.climatehubs.oce.usda.gov/midwest

Accumulated Precipitation (%)

12/1/2000–2/28/2001

Departure from Normal Temperature (° F)

12/1/2000–2/28/2001

Images courtesy of: Midwestern Regional Climate Center, Illinois State Water Survey, Prairie Research Institute

University of Illinois at Urbana-Champaign

Image courtesy of: Mark Longstroth, Michigan State Extension Image courtesy of: Illinois-Indiana Sea Grant Image courtesy of: Illinois-Indiana Sea Grant

Great Lakes Partners