Figure 1. Precipitation distribution for southern Nebraska during summer (June – August) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. The upper and lower blue lines indicate that the 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates that 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Source: NWS Climate Prediction Center ENSO data)

Figure 2. Temperature distribution for southern Nebraska during summer (June – August) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. Upper and lower blue lines indicate 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Data source: NWS Climate Prediction Center ENSO data)

Figure 3. Precipitation distribution for southern Nebraska during fall (September – November) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. Upper and lower blue lines indicate 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Data source: NWS Climate Prediction Center ENSO data)

Figure 4. Temperature distribution for southern Nebraska during fall (September – November) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. Upper and lower blue lines indicate 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Data source: NWS Climate Prediction Center ENSO data)

Figure 5. Precipitation distribution for southern Nebraska during spring (March – May) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. Upper and lower blue lines indicate 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates that 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Data source: NWS Climate Prediction Center ENSO data)

Figure 6. Temperature distribution for southern Nebraska during spring (March – May) for three ENSO phases, i.e. El Nino, La Nina, and Neutral, based on historical data since 1950. The red line indicates 50% of the observations for this location and season lie below this precipitation value. Upper and lower blue lines indicate 67% (upper blue line) and 33% (lower blue line) of historical observations lie below that value. Similarly, the black line indicates 90% (upper black line) and 10% (lower black line) of historical observations lie below that value. (Data source: NWS Climate Prediction Center ENSO data)

What Is El-Nino?
Does That Influence Ag Decisions?

The National Oceanic and Atmospheric Administration (NOAA) has issued an El-Niño Watch, meaning that the conditions are favorable for the development of El Niño within the next six months, specifically during late summer or early fall. Most of the models indicate the transition from the current neutral phase to an El Niño condition during the summer. The chances for an El-Niño exceed 70% during summer and 80% by fall, according to NOAA's most updated information. However, it is still uncertain exactly when El Niño conditions will evolve and how strong they will be. Currently we are still in a neutral condition; Table 1 shows probabilities of El Niño for summer through next winter.

What is El Niño, La Niña, Neutral, and ENSO?

In simplified terms, when the sea surface temperature in the equatorial Pacific is unusually warm for a certain time, the condition is defined as El-Niño. In contrast, when equatorial Pacific temperatures are unusually cool, La-Niña conditions arise. Currently, we are in a neutral phase, meaning that the equatorial Pacific sea surface temperature is neither warmer nor cooler than usual. Altogether, the phenomenon is called El Nino Southern Oscillations (ENSO).

What is the Connection Between El Nino and Nebraska's Climate?

How Could that Affect Agricultural Decisions?

ENSO impacts climate across the world, its impact differing from one region to another. Let's explore the connection between ENSO and Nebraska's climate. NOAA has a tool which shows historical distribution of temperature and precipitation for different climate divisions under ENSO phases, i.e. El Niño, La Niña, and Neutral. Figures show differences in spring, summer, and fall temperatures and precipitation with respect to ENSO phases for southern Nebraska climate divisions.

We are not yet in El – Niño conditions, but if this conditions takes place during the summer (June – August), based on these plots, we might expect slightly cooler and wetter conditions during the summer. This could be favorable for growth and development of important crops such as corn and soybean. Chances of El-Nino in fall exceed 65% at this time.

According to the comparison, El-Niño years are expected to be wetter and cooler than neutral and La-Nina years during the fall (Sept – Nov). Also, the variability in fall precipitation during an El-Niño year is considerably lower compared to a La-Niña year, giving more confidence that El-Niño years are likely to be wetter than neutral or La-Niña years. This could potentially influence harvesting decisions due to both cooler and wetter conditions. During an El Niño, spring (March-May) is slightly cooler and wetter than La Nina but drier than the Neutral conditions. This could influence spring planting decisions.

Why is Predicting ENSO Events so Important for Agriculture?

The ENSO phenomenon has a significant influence in predicting short-term and seasonal climate. It improves skills in the climate outlooks that NOAA produces for various time scales. Advance understanding of what to expect in terms of climate later this year and into the next year could help producers make better informed decisions. It also could help them mitigate adverse impacts or provide an opportunity to take advantage of favorable conditions. Additionally, it could provide some indication of expected above or below average crop yield ahead of time.

How Can ENSO Impact Nebraska Crop Yields?

One of the strongest indicators of why ENSO and other climate forecast information is important in agriculture is to understand its impacts on crop yields. I found a USDA-ARS article related to this very useful. It analyzed ENSO effects on corn and winter wheat yields for five states including Nebraska. According to this report, a warm episode (El-Nino) during July to September tended to have resulted in above trend-line corn yield for Nebraska. A warm episode (El-Niño) during November to January also tended to have resulted in above trend-line winter wheat yield for Nebraska. It is important to remember that this summary is based on historical warm (El Niño), cold (La-Niña), and Neutral events.

Given the complexity of the atmospheric system and the interactions among oceanic and atmospheric parameters, this information should be considered with some level of uncertainty. It is also important to consider that the ENSO explains only part of the climate variability we experience. Many other large scale oceanic and atmospheric climate indices also influence the climate, ranging from small time scales to a year to multiple decades.

I will keep exploring such climate connections with Nebraska agriculture and periodically report to Crop Watch.

Tapan Pathak
Extension Educator in Climate Variability