La Niña conditions are continuing to evolve in the Pacific and last through the winter months, with the Climate Prediction Center predicting that this latest one will likely reach strong magnitude. This large scale component of the Earth's climate system, although located in the tropical Pacific, can have impacts on our weather here in the Tennessee Valley. Granted, impacts in other parts of the world can be much more significant, with large scale changes in precipitation and temperature patterns, depending on the strength and character of the La Niña. Nevertheless, here's a look at how temperature and precipitation in our region have been affected by La Niñas of the past (since 1896).
To see past effects for a particular region, click on the Temperatures or Precipitation links within the appropriate regional map.
To learn more about La Niña or El Niño, including how these phonemena are monitored, impacts to other parts of the globe, the latest updates and data, and forecast information, you may follow the links below...
The El Niño theme page from the Pacific Marine Environmental Laboratory
The El Niño Southern Oscillation (ENSO) page from the Climate Prediction Center
Notes about this project
In order to obtain a relatively large sample size, this study utilized data between the years 1896 and early 2010. Sea surface temperature anomalies for the Niño 3.4 Region were derived from the Kaplan sea surface temperature (SST) dataset (Kaplan Extended SST V2) obtained from the International Research Institute for Climate and Society. It should be noted that this dataset contains different anomaly values than the Oceanic Niño Index utilized by the Climate Prediction Center for the classification of El Niño and La Niña episodes. However, the two datasets do exhibit reasonable similarity in the overlapping years since 1950. Additionally, it was discovered during the course of this study that temperature and precipitation values for the central Tennessee Valley region are more strongly correlated with the derived Kaplan SST dataset. Thus, the Kaplan SST data values serve as a better predictor of impacts in our region.
Temperature and Precipitation data for the climate divisions were obtained from the Physical Science Division of NOAA's Earth System Research Laboratory.
The magnitude of La Niña conditions in this study are defined as following:
Neutral Conditions...November through January average sea surface temperature anomalies in the Niño 3.4 Region of between 0.6 °C and -0.4°C
Weak La Niña...November through January sea average surface temperature anomalies in the Niño 3.4 Region between -0.4°C and -1.4°C
Moderate La Niña...November through January sea average surface temperature anomalies in the Niño 3.4 Region between -1.4°C and -1.9°C
Strong La Niña...November through January absolute sea average surface temperature anomalies in the Niño 3.4 Region greater than -1.9°C
The latest monthly Kaplan SST anomalies in the Niño 3.4 Region through the end of October are -1.4°C, and have been steadily decreasing. November through January Values lower than -1.9°C are possible, so a moderate or strong La Niña based on Kaplan SST values appears possible, if not likely.
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