ENSO Update 2025

[William Monfredo]

A brief update on El Niño Southern Oscillation (ENSO). We've been experiencing La Niña conditions this winter, and it appears that it will continue or change a bit perhaps to neutral conditions through May. That's decent news for chasers, especially if you have the flexibility to chase in March & April, too, IMO. A lag-time of several months or a season is nothing unusual for an ocean-atmosphere teleconnection, so what we see now will affect us later. CPC figures below show departures.

 

[William Monfredo]

A closer look into this ENSO situation, with some conflicting signals between the ocean and the atmosphere.
The oceanic portion of La Niña can be described as weak over the last couple of months...

Yet, the oceanic, subsurface temperatures have been the third coldest since 1979 record-keeping...

And with this "weak" La Niña, the atmospheric portion of the ENSO, is unusually strong, oddly enough.

The fine print... ENSO's but one player among many variables. I didn't want to muddy the waters of the "State of the Chase Season" thread.
But, looking back to last year, the oceanic portion of ENSO (El Niño) was the stronger player compared to the atmospheric aspect. This year, it's the opposite, with the atmospheric aspect being notably stronger than the oceanic (La Niña).
And last year was somewhat similar to 2011, in that we had what I would call a "great" transition out of El Niño for tornadoes.
This year, we appear to hang on to La Niña's favorable effects into the tornado season as it transitions the other way toward neutral.
And while there are statistically-significant correlations of seasonal totals for strong & violent tornadoes in varying regions of the country with the differing phases of ENSO, it's generally not a slam-dunk. But nonetheless, if the synoptics and mesoscale cooperate, I'm optimistic.

 

[William Monfredo]

So, now that we're clean up to ENSO neutral as of today, how have big Spring tornado-days this year compared to the 2006 analogue?

Just anecdotally, this year has been uncannily similar to 2006 with both the timing (mid-March and then early April, with the latter even falling on the same calendar day!) and geographical location (centered on the mid-MS Valley) of two significant early-season outbreaks.

 

[Andy Wehrle]

So, now that we're clean up to ENSO neutral as of today, how have big Spring tornado-days this year compared to the 2006 analogue?

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Yup, we were just missing that 3rd outbreak on the 6th-7th; although this year's active stretch did continue beyond the 2nd.

 

[Hannah.Taylor]

@William Monfredo I'd be curious to see the difference between the months in May for NON-ENSO neutral years vs. this month (May 2025) for supercell storms and tornadic activity.

It really seems like severe weather fell off after the shift from La Niña to ENSO neutral.