Tornadic La Nina In Action

[Bill Tabor]

With several tornadic outbreaks now under our belt and one on the way perhaps Thursday that have been focusing on AR MO and midwest what do you think? Is this sign of La Nina in action as we had talked about a month or two ago? BTW how many outbreaks has it been now? I have lost count.

 

[Marc Austin]

As far as I knew, we weren't yet into full blown La Nina, so I would say this is having a minimal effect, if any, on the number of outbreaks we have seen so far. These outbreaks, in my own unprofessional and untrained opinion, are the result of a warmer-than-average winter which has resulted in a more spring-like severe weather scenario earlier in the season. I'm hoping this isn't true because if it is I will most likely be chasing in South Dakota come May, although.. I guess that wouldn't be so bad... it is very flat. Anyway, this is my opinon... nothing based on any scientific proof or anything.

 

[Bill Tabor]

I heard we are in full blown La Nina.

 

[Justin Turcotte]

Some research suggests an increased thunder and tornado threat in the Ohio and Tennessee River Valleys during La Nina events as the jet stream is enhanced over that area. If so than this year fits into the mix reasonably well though other factors could also be in play. A decrease in rain over Florida during La Nina has been correlated in numerous formal papers. Florida is dry this year as well. I did course research paper dealing with teleconnections and winter season F1+ tornadoes in Florida. Nothing passed the 95% significance test as two El Nino events produced a huge number of tornadoes while the others were relatively "normal". One interesting observation was La Nina season tornadoes were heavily weighted toward the panhandle while El Nino season tornadoes were heavily weighted toward the central peninsula so perhaps a geographical shift which fits in with the changing jet regime. Since there is no "perhaps" selection on the poll I'll hit the "likely" button.

 

[Andrea Griffa]

It seems that the anomalies have to go ahead just during the next months as well.
Here is a good forecast map of the Nino 3.4 region:

Moreover there's an interesting animation of the last months that shows La nina.