Monday, April 27, 2015

Is a Strong El Nino FINALLY coming?

Last year about this time, the media was abuzz about a Super El Nino that would hit over the past winter (2014-2015).  Dramatic predictions were made for drought in the Pacific Northwest and heavy rains over southern California.

Unfortunately for the prognosticators, an official El Nino didn't occur although the waters in the tropical Pacific were slightly above normal.   Perhaps, we should have called it El Tepid.

But during the last few months the situation has altered substantially with temperatures in the central and eastern tropical Pacific surging upwards.   NOAA and Australian forecasters are now saying we are in an official El Nino and it appears it will become moderate or strong this year.

Let me show the details.  Here are plots of the sea surface temperature (SST) anomalies (differences from normal) for four critical zones in the topical Pacific. They are warming, with many of them being the warmest over the past year.  The usual definition for El Nino calls for a warm anomaly in the Nino 3.4 area of at least .5C for three consecutive months.  We got that now.

Here is a map of the SST anomalies for the past month.  Warm water (dark orange and red) stretching from the central Pacific to the coast of S. America.   You can also see the crazy warm water off our coast.

 NOAA has placed a series of buoys along the equatorial Pacific to keep track of the ocean temperatures below the surface.  These buoys show quite warm water extending 100-200 meters beneath the surface.  This figure shows an east-west cross section across the central Pacific of the underwater temperatures.  Red is much warmer than normal.

Bottom line:  we have now entered El Nino territory.  Based on a collection of models, NOAA's Climate Prediction Center (CPC) is going for El Nino conditions the remainder of this year (see their probabilistic forecast below).   Roughly 70% chance  this summer and about 60% chance next winter.  But this time of the year you have to be careful, with the quality of the winter forecasts improves radically by July and August.

The National Weather Service's primary seasonal prediction system, CFSv2, is based on running  weather/ocean forecast models out 9 months.    Its forecast is emphatic and confident (see below):  a strong El Nino will develop this summer and extend into next winter.

So what are the implications for the Northwest if a strong El Nino is in place next winter?  

We tend to be warmer than normal with less snow in the mountains (and much less snow in the lowlands).  Less stormy.  The good thing is that a typical strong El Nino year generally has more snow than the freaky year we just finished.  But this is not good news for ski areas.   On the positive side, El Nino years tend to bring more precipitation than normal to central and southern California.   And guess what?  The latest NOAA CFS model is showing exactly that for next October through December (see below).
Let me stress that there is a lot of uncertainty with this forecast and the models were not good last year.  But this year's warm water is more extensive than last and the models are more in agreement.  If the forecasts hold into mid-summer, our confidence in the strong El Nino prediction will be substantially enhanced.  So hold on but you decide on buying that ski pass at your favorite resort.


ryamkajr said...

Have they not called for an El Nino for three years in a row now? And been denied each time? Eventually they are bound to be right.
I know weather has lots of uncertainties and whatnot, but there is way too much of the "boy who cried wolf" syndrome in all aspects, especially around El Nino.

David Appell said...

It's surprising how much warmer the world has gotten since the big 1997-98 El Nino. We're easily beating its temperatures, almost every month, even though the past years's El Nino was slight-to-nonexistent.

Charlie Phillips said...

Uh... these pictures look familiar ;)

Dean said...

Depending on which agency you talk to, we _did_ have an El Nino last winter. The Japan Meteorological Agency declared one, though they base it on the Nino3 index.

Regardless though, the weather patterns from January through March were certainly El Nino patterns, and in particular El Nino Modoki patterns.

It was weak, but it was there.

Interestingly, because this was an El Nino Modoki (or a Central Pacific Warming as opposed to the classic East Pacific Warming), the atmospheric bridge caused a strong anomaly in the North Pacific Oscillation, which tends to then have a positive feedback on the tropics.

So having a 2nd El Nino would be totally consistent.

Albeit the CFS has a horrible track record of calling for El Ninos that don't happen.

Also, note that a Central Pacific Warming has a significantly different precip anomaly for California than an EPW. Very dry rather than wet.

Interesting that.

joanmagee said...

What is the difference between probabalistic and probable?

Wesley Plinke said...

"...keep track on the SST below the surface." hehe

dpc said...

Oh joy. Another hot summer and non-winter. My only hope is that stupid El Nino fizzles out and we finally get some good mt snow next year. CA included.

Jarv said...

My heating bills are wonderfully low this winter/spring. I am hoping for more of the same in the future years.

JewelyaZ said...

My electric car with low-rolling-resistance tires is not well-suited to snow, and I get better battery range with warmer winter temps, so I am thrilled. I am worried about our water situation, but it does seem like a good time to install photovoltaic panels. :-)

Sulla said...

Oh joy, so basically a repeat of the last 2 winters? I get that there will be debate about the underlying factors, but it boils down to more of the same. And this isn't even counting global warming!

Perhaps it should start to be news when there is NOT a forecast or reality of a warmer than normal winter with less than average snow in the mountains?

Doesn't seem to matter if El Nino fizzles or not either, sure didn't change much this past winter.

Chris Upham said...

Cliff what are your thoughts on El Nino's impact to the blob? I worry that without strong storms, the water will not be disrupted and we will have a warmer winter than normal because of the blob and a dryer winter because or El Nino. Perhaps problems lye ahead...

Paul Gibbons said...

I think the Meterologist and Geologists should get together and deduce the effect of Volcanic events effecting weather patterns.

Cailean said...

Just read this! And realized that I emailed you earlier on this same day, so thank you very much for your answer through this blog post...which helps many, not just me :)