Contacts: Ellen Mecray (Ellen.L.Mecray@noaa.gov)

     Northeast Regional Climate Center (nrcc@cornell.edu)

Eastern Region El Niño Impacts and Outlook|October 2015

www.drought.gov/drought/content/resources/reports

El Niño Impacts 

and Outlook

Eastern Region

October 2015

Typical El Niño Winter Pattern

Potential Winter Impacts 

An El Niño develops when sea surface temperatures are 

warmer than average in the equatorial Pacific for more 

than a season, altering the atmospheric circulation. This is 

important to North America because El Niño has an impact 

on our weather patterns, most predominantly in the winter.

Although each El Niño is different, there are some general 

patterns that are predictable. For instance, the polar jet 

stream is typically farther north than usual, while the Pacific 

jet stream runs across the southern United States (see figure 

to left). 

This pattern brings above-normal precipitation to southern 

parts of the Eastern Region, as the Pacific jet stream steers 

storms along the Gulf and southeast Atlantic coasts. The 

active Pacific storm track also promotes cloudy conditions in 

the Southeast, resulting in cooler-than-normal temperatures 

over the southern portions of the Eastern Region.

It is more difficult to define conditions in the northern 

sections of the Eastern Region because of other atmospheric 

and oceanic influences. The dry winter conditions that 

characterize Ohio and the Midwest extend eastward, with 

drier-than-normal conditions common in western New York 

and Pennsylvania. As storms often move up the coast during 

El Niño winters, the Eastern Seaboard generally experiences 

above-normal precipitation. Typically with strong El Niños, 

such as the one this year, warmer temperatures extend 

further into the Northeast than seen in the accompanying 

diagram. 

The image above shows the typical pattern during El Niño winters. The polar jet stream tends 

to stay to the north of much of the Eastern Region, while an active Pacific jet stream is present 

across the southern U.S. Since much of the Eastern Region lies between the two storm tracks, 

temperature and precipitation patterns vary considerably from south to north. It is important 

to note that this is a schematic diagram representing general patterns and is not created from 

actual data. For more information, please visit: https://www.climate.gov/news-features/

department/enso-blog.

Snowfall 

Across a broad swath of the Southeast, El Niño 

winter temperatures average 1 to 2 degrees 

cooler than those that do not experience El 

Niño conditions. Therefore, heating degree day 

accumulations tend to be higher during El Niño 

winters in this region. The Residential Energy 

Demand Temperature Index (REDTI) provides a 

population-weighted view of heating degree day 

accumulation in a region, thus giving a measure 

of year-to-year fluctuations in energy demand 

for residential heating. In the Southeast, seven 

of the ten highest REDTI values since 1950 

have occurred under El Niño conditions. Since 

energy consumption increases as the number 

of heating degree days increases, this winter’s 

El Niño is likely to increase energy usage as the 

demand for heating will be above average. With 

warmer than normal temperatures more likely 

in the Northeast, energy consumption will likely 

be lower, which is reflected in historical REDTI 

values during El Niño in this region. 

Snowfall along the Northeast coast is typically 

above average during El Niño winters. The 

exception to this is the lake-effect region in New 

York. Since 1950, six of the least snowy winters 

on record at Buffalo have occurred during El 

Niños. Typically, in regions closer to the coast, 

December through February snowfall is as 

much as 6 inches greater during such winters. In 

Washington, DC, eight of the ten greatest 2-day 

snowfalls since 1950 have occurred during El 

Niños. However, individual storm tracks can 

influence where precipitation falls as rain versus 

snow. Heavy East Coast snowfalls have negative 

impacts on transportation and the economy. 

Based on the Northeast Snowfall Impact Scale, 

an index that infers societal impacts based on 

the geographical extent and amount of snowfall 

along with population data, seven of the nine 

storms classified as crippling have occurred in 

conjunction with El Niño.

Energy Usage

Several research studies have noted an 

increased frequency of East Coast storms 

during El Niño winters. These storms, known 

as nor’easters, have a number of coastal 

impacts, ranging from beach erosion and high 

winds to heavy snowfall and precipitation. 

Storms that follow a classic nor’easter 

track from south of Cape Hatteras along 

the East Coast are the main contributor to 

this increase. Hirsch et al. (2001) found an 

additional two storms with this track occur 

during El Niño winters compared to other 

winters. Strong El Niño events are particularly 

associated with this increase. Significant 

snow storms such as the Blizzard of ‘58 and 

a second March 1958 nor’easter occurred in 

conjunction with El Niño conditions, as did the 

February 2003 Presidents' Day Storm. Storms 

such as the "Perfect Storm" in October 1991 

brought 15 to 30 foot waves to coastal New 

England during a strong El Niño. 

Coastal Storms
El Niño Outlook

Contacts: Ellen Mecray (Ellen.L.Mecray@noaa.gov)

     Northeast Regional Climate Center (nrcc@cornell.edu)

Eastern Region El Niño Impacts and Outlook|October 2015 

www.drought.gov/drought/content/resources/reports

Comparisons and Limitations Eastern Region Partners

National Oceanic and Atmospheric Administration

www.noaa.gov

National Centers for Environmental Information

www.ncei.noaa.gov

National Weather Service, Eastern Region

www.weather.gov

NOAA Fisheries Science Centers and

Regional Offices, Atlantic

www.nmfs.noaa.gov

Office for Coastal Management

www.oceanservice.noaa.gov

NOAA Research, Climate Program Office and

Geophysical Fluid Dynamics Lab

www.research.noaa.gov

NOAA National Sea Grant Office

www.seagrant.noaa.gov

NOAA’s North Atlantic, South Atlantic, and Great

Lakes Regional Collaboration Teams

www.regions.noaa.gov

Climate Prediction Center

www.cpc.noaa.gov

National Operational Hydrologic Remote Sensing Center

www.nohrsc.noaa.gov

Northeast Regional Climate Center

www.nrcc.cornell.edu

Southeast Regional Climate Center

www.sercc.com

National Integrated Drought Information

System

www.drought.gov

Carolinas Integrated Sciences and Assessments

www.cisa.sc.edu

Consortium on Climate Risk in the Urban Northeast

www.ccrun.org

Cooperative Institute for North Atlantic Research

www.cinar.org

Eastern Region State Climatologists

www.stateclimate.org

#regionalclimateoutlooks

Winter Conditions During Past El Niños 

The maps above illustrate the winter conditions of the record-breaking El Niño of 1997–98. 

Almost the entire region was warmer than average. Precipitation signals varied across the region. 

While the Ohio Valley and western Pennsylvania saw near-average precipitation, much of the 

Mid-Atlantic and Carolinas saw above-average precipitation. Despite El Niño's tendency to bring 

snowier-than-average winters to the East Coast, above-average temperatures led to belowaverage snowfall for most of the region. While the current El Niño is on track to be one of the 

strongest on record, please note that each El Niño is different. 

Other factors can also affect winter conditions, such as pre-existing global snow cover patterns 

or climate variability associated with the Arctic Oscillation and the North Atlantic Oscillation. The 

Arctic Oscillation trumped El Niño during the winter of 2009–10. A similar situation occurred 

during the winter of 1965-1966 when expected El Niño precipitation was subdued due to a strong 

negative North Atlantic Oscillation. The problem associated with these patterns is that they are 

less able to be forecasted far in advance compared to El Niño, meaning that it is uncertain as to 

how much they will affect the upcoming winter season.

Winter Temperature and Precipitation Outlooks El Niño Strength

Winter 2015-2016

A

Atmospheric and oceanic observations through 

October 2015 and the mean of the IRI forecast 

plume values thereafter reflect a strong El Niño, 

persisting into early 2016. Currently, this El 

Niño ranks among the strongest on record, with 

the forecasted strength potentially exceeding 

the 1997-98 El Niño. According to the Climate 

Prediction Center, strong El Niños occur when 

the 3-month running-mean of sea surface 

temperature departure in the Niño 3.4 region of 

the central Pacific exceeds 1.5°C. Research has 

shown that strong El Niños are often followed 

by La Niñas, so conditions should continue to 

be monitored, especially if the El Niño weakens 

in the spring, as predicted.

As of October, the winter outlooks resemble the classic El Niño temperature and precipitation 

anomaly patterns for the region. The below-normal precipitation that is favored for the Midwest, 

extends into Ohio, while above-normal precipitation is very likely for the coastal Carolinas. 

This area of above-average precipitation extends through much of the coastal plain from the 

Carolinas to New England. Meanwhile, the temperature outlook indicates that the northern 

parts of the Eastern Region are more likely to experience above-normal temperatures. This 

pattern is supported by several climate model runs and is consistent with past strong El Niños. 

In the extreme south, increased chances for colder-than-normal temperatures are predominant. 

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

long-term trends, and soil moisture, in addition to past El Niño patterns. Therefore, they may not 

match typical El Niño conditions exactly. To learn more about these outlooks or see the latest 

temperature, precipitation, and drought outlooks, please visit the Climate Prediction Center at: 

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

Valid for December 2015–

February 2016

A: Above-normal

B: Below-normal

EC: Equal chances of 

above-, near, or belownormal 

Number: Probability of 

above- or below-normal

A

B EC

EC

A

B 33

40

33

50

40

40

33 33

50

60

70