Besides some noteable severe weather events in the southeastern us, it has been a fairly quiet march and april in regards to severe weather. But what does the rest of spring look like?
As always, there is no way we can exactly forecast what will happen, but what we can do is look at the big picture trends to give us a clue as to what things could look like. And there is no better trend to look at than ENSO, or El Nino Southern Oscillation.
ENSO is the cycle of warmer than normal, or cooler than normal sea surface temperatures in the eastern and central parts of the Equatorial Pacific caused by a reversal of the winds.
We’ve been in La Nina since October, and we just got through a La Nina winter, when the waters in the Pacific are cooler than normal, and that La Nina trend continues to this day.
The reason this has an impact on our climate, even remotely here in the Midwest, is because the Pacific is one of the largest sources, and sinks, of energy. It’s a giant body of water, and so it effects the flow of the jet stream.Trent Ford, Illinois State Climatologist, University of Illinois
With a La Nina like we have, especially when it lasts into the spring, this pushes the jet stream further to the north while also causing it to become more amplified on average. An El Nino jet stream is what we call zonal, which is straighter and thus more of a quiet pattern compared to La Nina.
When it comes to severe weather, pretty much from throughout the Southeast US, from the Gulf Coast all the way up to the central Midwest, including most of the state of Illinois, we tend to see a little more active severe weather season in La Nina, which is the phase we are in now.”Trent Ford, Illinois State Climatologist, University of Illinois
In conclusion, the overall picture is that this could be a more active severe weather season than normal, but we will have to see how more localized events play into the trend. Hopefully, this continues to be a calm year for us across the state. Doctor ford does give us this good news:
We’ve gone three consecutive years in the state of Illinois without a tornado related fatality… I’d credit that to meteorolgists such as yourselves, providing good warnings, good awareness from the national weather service offices, that sort of thing. The last time we went four consecutive years without a tornado related fatality in Illinois was back in the mid 90’s.Trent Ford, Illinois State Climatologist, University of Illinois