Monday, July 20, 2015

More Record Global Temperatures with El Niño on Tap for Winter

The National Centers for Environmental Information released their global analysis for June today.  The global surface temperature for the month was easily the warmest on record, beating last year's record by a 0.12ºC (0.22ºF).

Source: NCEI
For the calendar year to date, we're also well into record territory with the January–June 2015 temperature .09ºC (.16ºF) higher than the previous record holder, 2010.  

Source: NCEI
In addition to the long-term global warming trend, this year is jacked up by El Niño, and many seasonal climate models are calling for a strong event this winter.  The Climate Prediction Center is now calling for a 90% chance that El Niño will continue through the winter and an 80% chance it will persist through early spring.

As we have discussed many times previously (e.g., Outlook for the 2013–2014 Ski Season), there is not a strong correlation between El Niño and snowfall in the central Wasatch, as can be shown below for snowfall records at Alta.  A pessimist might say the odds are weighted slightly toward lower snowfall, but I wouldn't bet the ranch on that given the scatter.

This is generally consistent with the maps below showing the average precipitation rank by climate zone during El Niño events for November to December (top) and January to March (bottom).  Evident is a pronounced precipitation dipole favoring wetter than average conditions in the southwest and drier than average conditions in the interior northwest.

Source: CPC
Source: CPC
You'll see maps like these in the coming months.  There may be some variations depending on the definition of El Niño used and the length of the period of record, but the basic idea of a precipitation dipole with northern Utah sitting in the transition zone is a robust feature.  

Nobody has to be more excited about this than California, which sorely needs the rain.  Although they can be skunked during El Niño years, the odds of a wet winter are clearly stacked.   

Source: CPC
Ditto for Arizona and especially New Mexico. 

This relationship between El Niño and precipitation forms a strong basis for the the Climate Prediction Center precipitation outlooks below.  Dry northwest interior with a wet southwest.  

Source: CPC
Let's hope the southwest finally gets some this winter, but that it also comes in manageable amounts.  Let's also hope that the storm track sets up in a way that the Wasatch benefit too.  


  1. In addition to El Nino, we are finally in a positive PDO phase with jacked East Pacific SSTs all the way to Alaska. Meanwhile, the AMO is no longer strongly positive. I wonder if these shifts may help to push the positive precipitation anomaly associated with El Nino a bit farther north (although they also might impact temperatures). Do you know how Wasatch snowfall responds to combined ENSO-PDO-AMO phases?

    1. I don't. That would be interesting to check, although it could be slicing the onion pretty thin.

      For what it's worth, the CFS is generating a fairly typical El Nino precip dipole over western North America for DJF for all 3 ensemble suites, although the strength of the anomalies varies (the position of the transition zone also exhibits a small amount of variability).

    2. I found this paper: If you believe their results, then it seems like the PDO and AMO modulate the precipitation anomaly magnitudes associated with ENSO more than the pattern, in which case, they also may not significantly impact Wasatch wintertime precipitation.

    3. It's actually quite remarkable how little correlation there is between northern Utah precipitation and any of these indicies. Everyone loves an answer, but in this part of the world, there's typically very little we can say about the coming winter.

      The deck is looking really stacked for the southwest though.