National Weather Service United States Department of Commerce
Weak El Niño Conditions Favored for the Upcoming Winter

The outlook from the Climate Prediction Center for the upcoming winter of 2018-2019 is saying that a weak El Niño is favored to develop and influence the weather across the United States. El Niño is associated with warmer than normal water temperatures in the Equatorial Pacific Ocean, unlike La Niña which is associated with cooler than normal water temperatures. Both of these climate phenomena, which typically occur every 2-5 years, influence weather patterns throughout the world and often lead to extreme weather events. Over the United States during an El Niño the Jet Stream is usually stronger and located further south across the southern U.S. and Florida during the Winter and early Spring. As a result, low pressure systems tend to form farther south, often tracking from the Gulf of Mexico east or northeast across the Florida peninsula. This storm track usually leads to above normal rainfall across West Central and Southwest Florida, along with an increased threat of severe weather, particularly along and ahead of cold fronts moving down the peninsula.

All images on this page can be magnified by clicking, and resized back to original size with a second click.
 
Typical Wintertime Pattern during El Niño



CPC Outlook for Winter 2018-2019:

The overall forecast for West Central and Southwest Florida for the upcoming winter is for a better chance of above normal rainfall with equal chances of above, below, or near normal temperatures as can be seen in the Climate Prediction Center Winter Outlook graphics below. If we get a typical El Niño pattern we should see storm systems move across the region every week or so bringing clouds and some rain, which will be good for our landscapes, but not so great for the vacationers. There will likely be a few freezes across the region, especially over the Nature Coast, but prolonged cold weather is not anticipated at this time. Drought conditions are not anticipated to develop until maybe next Spring when the El Niño typically has begun to weaken with less storminess and more fair, warm days return.


CPC Winter 2018-19 Precipitation Outlook

CPC Winter 2018-19 Temperature Outlook


U.S. Seasonal Drought Outlook



In the following sections is more detailed information and graphics about how ENSO affects the weather across West Central and Southwest Florida. Click on one of the buttons below to go directly to that section. Also, all images can be magnified by clicking, and resized back to original size with a second click.


History:

We had weak to moderate La Niña conditions during the last two winters and now a weak to moderate El Niño is expected by this winter. As is typical during La Niña winters we saw below normal rainfall with temperatures a couple of degrees above average the last two years, but this winter into next spring we are expecting the opposite with above normal rainfall and temperatures slightly below normal. Before this a previous strong El Niño occurred during the winter of 2015-16 which brought above normal rainfall and a few severe weather events.

Following are U.S. maps of the Winter (December-February) departure from average precipitation and temperature for each category of El Niño and La Niña since 1950.

El Niño PrecipitationWinter (Dec-Feb) Precipitation during strong, moderate, and weak El Niños since 1950   El Niño TemperatureWinter (Dec-Feb) Temperature during strong, moderate, and weak El Niños since 1950
 


La Niña PrecipitationWinter (Dec-Feb) Precipitation during strong, moderate, and weak La Niñas since 1950   La Niña TemperatureWinter (Dec-Feb) Temperature during strong, moderate, and weak La Niñas since 1950

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Rainfall:

During El Niño there tends to be more stormy conditions across the Florida peninsula during the winter and early spring. Cold fronts will move across the region and with the jet stream further south and stronger, rainfall is more widespread and therefore usually above average. This can be seen in the graphics below where rainfall totals during the dry season average much higher during El Niño winters then during La Niña winters.

Inverness 3 SE Average Monthly Rainfall by ENSO Category   Inverness 3 SE Average Rainfall Total by ENSO Category
 
Brooksville Average Monthly Rainfall by ENSO Category   Brooksville Average Rainfall Total by ENSO Category
 
Tampa Average Monthly Rainfall by ENSO Category   Tampa Average Rainfall Total by ENSO Category
 
Lakeland Average Monthly Rainfall by ENSO Category   Lakeland Average Rainfall Total by ENSO Category
 
Sarasota-Bradenton Average Monthly Rainfall by ENSO Category   Sarasota-Bradenton Average Rainfall Total by ENSO Category
 
Arcadia Average Monthly Rainfall by ENSO Category   Arcadia Average Rainfall Total by ENSO Category
 
Punta Gorda Average Monthly Rainfall by ENSO Category   Punta Gorda Average Rainfall Total by ENSO Category
 
Fort Myers Average Monthly Rainfall by ENSO Category   Fort Myers Average Rainfall Total by ENSO Category

Another way to see this is by viewing the Box and Whisker Distribution Plots* for the three climate zones across the Florida peninsula shown below:

DJF Precipitation Distribution for Climate Div. #066 DJF Precipitation Distribution for Climate Div. #067 DJF Precipitation Distribution for Climate Div. #068
Northern Florida Peninsula Central Florida Peninsula Southern Florida Peninsula

*To better understand these plots visit the following CPC web page:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/box_whiskers/info.php

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Temperature:

The link between ENSO and wintertime temperatures is a little bit weaker. With the average storm track farther south during El Niño temperatures tend to average slightly below normal thanks to the increased clouds and rain that keep daytime highs cooler. This is in contrast to La Niña where we usually see drier air over the state with more fair weather days. This drier air leads to warmer daytime and slightly cooler nighttime temperatures that overall usually result in slightly above average temperatures across the area.


Inverness 3 SE Monthly Departure from Normal Temperature by ENSO Category   Brooksville Monthly Departure from Normal Temperature by ENSO Category
 
Tampa Monthly Departure from Normal Temperature by ENSO Category   Lakeland Monthly Departure from Normal Temperature by ENSO Category
 
Sarasota-Bradenton Monthly Departure from Normal Temperature by ENSO Category   Arcadia Monthly Departure from Normal Temperature by ENSO Category
 
Punta Gorda Monthly Departure from Normal Temperature by ENSO Category   Fort Myers Monthly Departure from Normal Temperature by ENSO Category


This can also be seen in the Box and Whisker Distribution Plots* for the three climate zones across the Florida peninsula shown below:

DJF Temperature Distribution for Climate Div. #066 DJF Temperature Distribution for Climate Div. #067 DJF Temperature Distribution for Climate Div. #068
Northern Florida Peninsula Central Florida Peninsula Southern Florida Peninsula

*To better understand these plots visit the following CPC web page:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/box_whiskers/info.php

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Freezes:

Freezing temperatures are possible into Central and South Florida during any winter no matter if ENSO is in El Niño or La Niña. What plays a larger role in controlling temperatures across Florida during the winter and early spring is the Arctic Oscillation (AO) as we saw back in early 2010. This oscillation shifts on a monthly and sometimes weekly basis and typically is not included in long term forecasts. For more details visit Arctic Oscillation: Impacts on West Central and Southwest Florida.

During El Niño conditions the likely cause of freezing temperatures is advection of cold air dragged southward behind low pressure systems that pass across the state. This is unlike La Niña conditions where the main cause is radiational cooling under clear skies and calm winds.

Long term averages indicate three to six days of freezing temperatures each winter across inland portions of Central Florida with only about one freeze over Southwest Florida. Farther north across the Nature Coast many more days of freezing temperatures occur with some locations such as Inverness and Bushnell having on average around 12 days, while further north near Chiefland there are as many as 20 days with temperatures falling to or below freezing each winter. Overall the difference in the number of days with freezing temperatures is not that much between La Niña winters and El Niño winters as seen in the following graphics.


Inverness 3 SE Average Number of Freezes per Cool Season by ENSO Category   Brooksville Average Number of Freezes per Cool Season by ENSO Category
 
Tampa Average Number of Freezes per Cool Season by ENSO Category   Lakeland Average Number of Freezes per Cool Season by ENSO Category
 
Sarasota-Bradenton Average Number of Freezes per Cool Season by ENSO Category   Arcadia Average Number of Freezes per Cool Season by ENSO Category
 
Punta Gorda Average Number of Freezes per Cool Season by ENSO Category   Fort Myers Average Number of Freezes per Cool Season by ENSO Category

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Other Web Sites:

NOAA Winter Outlook Press Release
https://www.noaa.gov/media-release/winter-outlook-favors-warmer-temperatures-for-much-of-us

Climate Prediction Center
http://www.cpc.ncep.noaa.gov/

NOAA Climate.gov ENSO Page
https://www.climate.gov/enso

NOAA Climate.gov Arctic Oscillation Page
https://www.climate.gov/news-features/understanding-climate/climate-variability-arctic-oscillation

NWS Tampa Bay Local Arctic Oscillation Page
https://www.weather.gov/tbw/tampabayaopage

January 2010 Cold Snap
NWS Tampa Bay 2009-2010 Winter Newsletter

Current Drought Conditions in Florida
https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?FL

Drought Outlook
http://www.cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.php

NWS Tampa Bay Local Drought Page
https://www.weather.gov/tbw/droughtinfo


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