Wimpy El Nino

We are now close enough to the winter season to have a fairly clear idea of the El Nino situation ahead.  Remember that El Ninos are associated with warmer than normal water in the tropical Pacific and that such anomalies can influence Northwest weather (less storms, warmer, less snow).

Originally there was a lot of talk (last spring) of the potential for a Super El Nino, with some of the global warming "advocate" sites talking about its effects on the global temperature record (global temperatures can warm substantially with strong El Ninos).

However, the sea surface temperatures in the critical  central Pacific is only modestly warmer than normal and the atmospheric circulation has not reacted in a way to reinforce the warming and push us towards a moderate or stronger El Nino.

Let's start with one of the key measures:  the sea surface temperature in the Nino 3.4 area of the tropical Pacific.  The official definition of El Nino is an anomaly  there greater than .5C.  We are not there now and in fact the SST has declined recently.

A number of groups run statistical and full-physics models to simulate El Nino.  They suggest we will have an El Nino, but a weak one.  However, verifying these models for the forecasts started earlier in the year, suggest they have been pushing warming in an unrealistic way.

The National Weather Service Climate Forecast System (CFS) model is now going for an entirely marginal event, barely reaching the .5C criterion

And the official probabilities for El Nino are now only about 65%.

So we should not expect much more than a marginal El Nino during the upcoming fall and early winter months.  And amplitude matters.   Weak El Ninos have lesser impacts.

The correlation of our weather with El Nino is not perfect to start with.  And for weak El Nino years the relationship weakens further.

Let me illustrate this for you.

Here are the precipitation patterns across the U.S. for some STRONG El Nino years.  The most consistent implication is  the wetter southeast U.S.   There is a tendency for southern/central California to be wetter.  The Northwest is less consistent.

But for weak El Nino years, the precipitation patterns are all over the place.  I would not place bets on anything.  This is the story of our upcoming winter unless El Nino revs up unexpectedly.

So based on the correlation with El Nino, we have very little guidance for the upcoming winter. Sorry.

The latest NWS Climate Forecast System forecasts for December-January-February is for warmer than average over much of the U.S.  No hint of the feared "polar vortex."

What about precipitation?  Very little signal over the Northwest.  But wow...California is much wetter than normal.  This would really help the drought.  Fingers crossed.

And this week should be a shock to some.  Showers today.  Generally dry on Sunday and Monday day.  But they the celestial spigots will turn on.

Hopefully, the rain will be over by next Saturday.  Why?   Because one of my favorite events will occur Sunday morning at 9AM:  the UW Dawg Dash fun run.  For more information, check out their site: http://depts.washington.edu/alumni/blogs/dawgdash/