Back in the fall, signs were pointing toward an El-Nino pattern forming as the water temps around the Pacific Equator were warming which indicates EL-Nino as a result I thought along with forecasters, that would impact our winter. However, as of this writing EL-Nino has not formed and the Climate Prediction Center now says there is a 90% chance that El-Nino will not form. The water temperatures as of this writing were staying average or a degree below average. So the CPC has given a 70% we stay in Neutral conditions and there is a 20% La-Nina returns and 10% El-Nino forms, each impacts weather in southeast Tennessee differently, I will skip El-Nino since it is the least likely to occur
Neutral is when El-Nino or La-Nina are not present. Looking back on historical data neutral gives us a chance of some winter events and temps tend to be close to average. The rest of the year, temps in the spring, summer and fall, tend to be slightly above normal. Rainfall tends to be close to average basically things are in a balance.
La Nina Conditions
La Nina really impacts our weather. Winters are typically mild and very wet. Spring and Fall are often more stormy while summers tend to be dry. Overall La Nina brings well above average temps, above average rainfall and more stormy conditions.
Now how does El-Nino, La-Nina and Neutral affect Tornadoes?
The bottom line is all three conditions have brought tornadoes to southeast Tennessee. The thing to remember is regardless of the pattern, if cold air collides with warm air in the atmosphere, plus wind sheer and if moisture is present than it creates favorable conditions for tornadoes. So the bottom line is regardless of the pattern if conditions are favorable tornadoes will occur.
Tornadoes have even occurred in El-Nino events here are some examples. March 1997 Easter brings tornadoes to Chattanooga, Cleveland and Polk County. November 2007 tornadoes touch down in South Pittsburgh
In 2009 which was a very strong El-Nino, April brought tornadoes to Chattanooga and Athens
Neutral has also brought tornadoes to the area. In November 2002 the Plateau outbreak occurred, this event brought tornadoes to the Plateau and southeast Tennessee.
May 2008, Tornadoes touch down in the area.
March 2nd 2012 the area is effected by an outbreak of tornadoes, this event also brought devastating tornadoes to Kentucky, Ohio and Indiana
La Nina is interesting concerning tornadoes, because it seems there might be a correlation between La-Nina patterns and tornadoes. However NOT every La-Nina event has brought tornadoes to our area but here are some examples
May 1995-tornadoes touch down all throughout Southeast Tennessee
April 16th 1998, The area has a tornado outbreak this outbreak is known as the Nashville outbreak or the Kentucky/Tennessee outbreak as tornadoes touched down in Kentucky, Middle and Eastern Tennessee
October 26th 2010, tornadoes touch down in Chattanooga, Cleveland and Monroe County
April 27th, 2011 this one needs no explanation as several tornadoes touched down in our area, this was part of the Super Outbreak of 2011