El Niño and its Effect on Florida

In the central and eastern Pacific, there is a lot of year-to-year variability. Some years are much warmer and wetter (El Niño), and some years are much cooler and drier (La Niña). We are in the midst of an El Niño phase of the ENSO (El Niño/Southern Oscillation) cycle. There is currently a strong El Niño present across the equatorial Pacific Ocean.  El Niño isn’t a storm that will hit a specific area at a specific time. Instead, the warmer tropical Pacific waters cause changes to the global atmospheric circulation, resulting in a wide range of changes to global weather. Think of how a big construction project across town can change the flow of traffic near your house, with people being re-routed, side roads taking more traffic, and normal exits and on-ramps closed. Different neighborhoods will be affected most at different times of the day. You would feel the effects of the construction project through its changes to normal patterns, but you wouldn’t expect the construction project to hit your house. For more information on regional effects around the United States, please watch this video.

Sea surface temperatures (SST) have been at least 1.5°C above-average across much of the central and east-central equatorial Pacific since May.  Peak is still expected during late fall / early winter, potentially near or exceeding 2°C.

SST

Based on current observations and dynamical model forecasts, El Niño is expected to strengthen and last through Northern Hemisphere winter 2015-16. A strong El Niño event is most likely this winter. El Niño should gradually weaken through the spring.

ENSO

El Niño has global impacts: some negative, some positive. Even for Florida and the Southeast U.S., some El Niño influences are beneficial; some not so beneficial.

  • El Niño has significantly reduced Atlantic hurricane activity this 2015 season.
  • El Niño is expected to bring above average precipitation to Florida during Fall-Winter-Spring…reduced risk of wildfires…higher risk of flooding.
  • Increased storminess across the southern U.S. increases the threat of severe weather in Florida this winter.

The overall El Niño impact for the Southeast U.S. this winter calls for cooler and wetter conditions this winter, not because of numerous arctic outbreaks, but because of the stronger influence of the subtropical jet stream. Storm tracks will then be farther south producing more clouds, rain, and potentially more severe weather.

TempOutlook

PrecipOutlook

Winter Precipitation

Florida winter rainfall distributions are explained below. The plots are box and whisker diagrams where the maximum and minimum amounts are the top and bottom of the diagrams, and the box describes the middle 33% of the cases. In all four Florida locations, the rainfall distribution is higher in the El Niño years.

PrecipDistribution

JetStream

LargeScale

There is a noticeable correlation between stronger and more frequent storms, particularly across the central part of the peninsula of Florida.

LaNinaVsElNino

Distilling the data further, there is also a direct correlation with more frequent severe weather and tornadic activity across Southeast Georgia and Northeast Florida associated with Strong El Niños.  During El Niño, there are strong systems that migrate across the Gulf of Mexico while there is ample moisture being pushed into Southeast Georgia and Northeast Florida with greater instability ahead of frontal systems that move into the region.

HailTornado

NEFLSEGA

The graphic below shows the seven recent Years of La Niña and Neutral Conditions across the region, and the associated, and more limited tornadic activity with it across SE Georgia and NE Florida.

ColdSeasonENSONeutralThe graphic below shows the seven strongest El Niño years and the tornadic activity associated with those particular combined El Niño seasons. Generally tornadoes that do develop during the strong El Niño season, tend to be longer in duration and stronger.  This is due to the ample pooling of moisture, stronger jet, and more frequent storms moving across the Gulf of Mexico with a more persistent southern jet stream.

ColdSeasonElNino

PublicAwareness

Preparation

Partnerships

PublicWeatherOutlook