La Nina Winter Impacts in the Tennessee Valley

La Niña conditions are continuing to evolve in the Pacific and last through the winter months.  The Climate Prediction Center (CPC) has indicated this winter's La Niña will likely reach moderate strength, and perhaps even a strong La Niña could develop.  The seasonal outlooks from the CPC above are largely reflective of those conditions.  Notice that above normal temperatures are favored for the region during the season overall, although this does not mean that cold outbreaks won't occur.  Based on all of the available evidence and the current state of the science to predict seasonal conditions, seasonally averaged above normal temperatures are favored during the period.  As far as precipitation goes?  Well, it's really a toss-up specifically for our region. 

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

If you have any questions or comments, please feel free to send them to sr-hun.webmaster@noaa.gov.