El Nino and the Jet Stream


My neighbor tells me that this rain we have been receiving is due to El Nino and I haven't been following it closely enough to give a good answer. I thought it had to do with the jet stream, but can it be affected by that phenomenon, too?


The recent run of wet weather is "PROBABLY" a function of the current "weak" El Nino ... and you are right about the active jet stream! The "linkage" is that during the winter and spring months of El Nino periods, the southern branch of the jet stream (AKA "subtropical jet
stream"-STJ) tends to become much more active and much more persistently positioned over the Gulf/Mex. The STJ brings us the high-level Pacific moisture (the repetitive high-level streaming stratus clouds seen overhead and on satellite pix) .. AND ... helps induce more frequent development of surface low-pressure centers off the Texas coast -- have you noted the frequency of lows developing in the western Gulf in recent weeks?

Many of these Gulf lows track ENE to NE towards the Bayou State, making for "wet" winter/springs for the southern half of the state. (The impact of El Nino for the northern parishes is much less predictable.)

During "strong" El Nino winter/springs, "wet" for south Louisiana for the Jan-Apr period is HIGHLY likely -- almost a sure thing. the only question is "how wet?" -- how much above normal?

But with this current "weak" event, there is a little less confidence that the recent wet pattern will continue through the next 3-4 months.
But even with a little less assurance, my suggestion to those interested in (or impacted by) recurrent wet weather at this time of year: "be prepared for more of the same."

Hence the "PROBABLY" noted above ... the recent wet spell is probably El Nino (or, at least, added to by El Nino) and will probably continue for a few months. El Nino has shown some signs of additional weakening in recent weeks ... we will be watching to see if this is a trend, or just a short shift in the "signal strength."

Jay Grymes
Chief Meteorologist
WAFB StormTeam