ST. PETERSBURG, Fla. -- Computer models are now forecasting a 70 percent chance of an El Nino developing in the Pacific for the upcoming 2018-2019 winter.  An El Nino is warmer than normal water over a vast area of the Pacific near the equator and off of the coast of South America.  This slight change in the ocean currents and slight increase in the water temperature can have major impacts on the weather in North America and even locally here in Florida.

While each El Nino is different, they have some common side-effects that change our weather for a few months.  The impacts of an El Nino are seen more in the winter months here in Florida as the jet stream is pushed south across the Gulf and overhead.

What could an El Nino do?

-Fewer hurricanes:  If an El Nino forms towards the end of the June-November Hurricane season, stronger than normal upper level winds can reduce the number of hurricanes in the Atlantic, Caribbean, and Gulf of Mexico.  This would most likely impact the last two months of hurricane season the most and may or may not have any impact on development in the heart of the season (Aug-Sept).

-More severe weather:  The last El Nino brought deadly tornadoes in January, and just as the destructive 1997-1998 Super El Nino brought round after round of severe weather and tornadoes to Florida in the winter, any El Nino can have us on edge for tornadoes and severe storms. 

This is because the upper level winds or jet stream which can cause wind shear and stronger systems are parked further south, often directly over Florida and the Gulf Coast, in an El Nino.  Almost all of the most significant tornadoes to hit the Florida peninsula have been during an El Nino. 

But not all of them are the same. We've had rainy and cool weather too, so cool severe storms couldn't form during an El Nino.  The good news is, we know the pattern and can advise you days in advance of possible severe storms and tornado risks during the normally dry and pleasant winter months here in Florida.

-More rain:  The Super El Nino of 1997-1998 produced record rain (over 10" in December 1997) and caused weeks and weeks of significant flooding.  But as I said, not all of them are the same.  We have had only slightly above normal rain during an El Nino in the past too.  Since our winters and "dry seasons" are so dry in a normal year, it doesn't take much to get above normal rainfall from November to April. 

-Cooler temperatures:  El Nino usually doesn't cause more cold fronts or invasions of Arctic air, but it does cause more cloudy and cool days which can bring overall temperatures down.  If cold air can intrude with the cloudy and rainy weather from the El Nino, it can lead to rather chilly and raw days around here during the time of year when many visit Florida for sunshine and an escape from winter's chill. 

We will keep you updated as we go along through the year toward late fall and winter on the development of an El Nino and what type of pattern we might expect this winter.