Today CPC (Climate Prediction Center) officially pulled the plug on the possibility of El Nino this winter. From late spring through summer, climate models tried to develop a moderate strength El Nino for the fall and winter. El Nino is a warming of the equatorial Pacific, La Nina is cooling. The whole package is ENSO (El Nino-Southern Oscillation).
The equatorial Pacific did indeed warm during the summer to marginal El Nino conditions, but then it stalled and actually cooled back closer to normal. The main region used to determine the status of ENSO is called Nino 3.4. Here’s a chart of all the ENSO regions over the past year:
You notice the 3.4 region warms, then cools close to normal recently (right side). Officially, El Nino conditions are 0.5 or higher in this region. So it was marginal in the summer, but is definitely now on the warm side of “neutral” and it appears that will continue the next couple of months, which is all that matters for our winter.
So what does it mean for this winter? Well, out of the last 3 official neutral winters (2008/2009, 2003/2004, & 2001/2002) two saw significant ice/snow storms here in the Portland Metro Area. Now many would argue 2008-2009 was a La Nina winter since it was right on the line between La Nina and neutral. Good point, only adds to the mystery if you ask me. If you take the 3 neutral winters before that you find 2 more years in which we had some good snow/ice action.
About a month ago, I looked much farther back in history to see what kind of winters we have had when we have weak El Ninos or neutral years that are on the warm side (like this coming winter). I saved that very detailed post as a tab. Click on WINTER 2012-2013 THOUGHTS up above.
Chief Meteorologist Mark Nelsen