February 07, 2024

A Dominating El Nino

Although the current El Nino may be entering its declining stage, the sea surface temperatures in the tropical Pacific are still quite war, and thus the impacts of the El Nino continue.

The evidence is very strong that this El Nino is the key driver of the low mountain snowpack this winter.    Let me show you.

Below is the latest snowpack situation from the SNOTEL network.  The western U.S. snowpack water content is below normal over the coastal states, ranging from about 80% of normal in California and Oregon to around 60% over Washington State.

So why this snowfall pattern?

The precipitation difference from normal for the past 60 days shows a relatively wet California and Oregon, but drier than normal conditions in western Washington and the Cascades.

And most of the west has been warmer than normal.  It all fits.  The temperature and precipitation pattern explains the snow distribution. 

But can we blame this on El Nino?  

NOAA has a nice webpage in which they show the typical winter conditions associated with El Ninos based on many events.

Precipitation? Wet California,  dry western Washington.  Looks like this winter!

The temperature during El Nino winters?  Warmer than normal over the West Coast.  Just like this year.

So the precipitation and temperature anomalies from normal fit the El Nino expectations like a glove.

Do you want even more evidence that the low snowpack has the fingerprints of El Nino all over it?

The warm western U.S. and wet California situation this year has been caused by persistent low pressure off the West Coast.    Here is a map of the difference from normal at the height of the 500 hPa pressure level (about 18, 000 ft) for December 1-February 5.   

An anomalous low is found offshore.  Such lows have warm southwesterly flow on their southern and eastern flanks.   This explains the warmth of this winter and wet conditions over California.  Note the higher-than-normal heights (pressures) over the northern Plains.

This is exactly the kind of pattern typical of El Nino years.   Want proof?  Another NOAA website has a composite of El Nino years for the same level.  Same pattern.  Strong low offshore.

Some local media are blaming the lack of Northwest snow on global warming, but they are wrong.  The cause is the naturally varying El Nino/La Nina oscillation.

A strong El Nino is the enemy of Northwest mountain snows.  

But this enemy has only months to live.  Wise reservoir managers understand that in such El Nino years, they must store as much water as possible during the rainy season.  The managers of the City of Seattle reservoir system are some of the wise ones--  Seattle's reservoirs are now well above normal! (see below).  I suspect there will be no lack of water for the Puget Sound region this summer.


  1. As for Portland, there's been only one forecaster that's mentioned the effects of El Nino on the weather for this winter, and I've yet to see any national forecasters mentioning this on a consistent basis. Wonder why?

  2. Given the latest national snow cover map, there isn't much to show for what is mid winter anywhere other than at higher elevation, Northern New England and Minnesota. That nationwide cold snap has more or less been all there has been to this winter in the USA. Chicago today will have highs near 60. In the 50s for NYC. Is there winter anywhere? Maybe in Europe? Asia? Probably a record breaker for sure. Yes, this blog discusses what goes on in the PNW, but sometimes the bigger picture is just not acknowledged at all. Maybe this lack of winter is perfectly normal.

    1. Yeah, perhaps the "lack of winter" is exceedingly normal for a strong El Nino, both for this country and around the world. Did you even read this post?

    2. Yes. I read it. This El Nino must be extra special (or extra savage) since typically it doesn't shut out the majority of the country from getting consistent winter weather. Not a couple weeks of cold but otherwise in the 50s even in Upstate NY.

    3. The map Cliff published shows NY/NE with a greater probability of above-average temps And yes, this el Nino has already been compared with some of the strongest episodes on record (e.g. 1997), so "extra savage" is (perhaps inadvertently) a reasonable description. Well played.

  3. That's a very compelling case Cliff, thank you for setting it on the page..

    But where there's no reservoirs, even "wise water managers" don't matter!

    There is one western-WA county that has a lot of commercial ag industry (berries, dairy) but has no reservoirs suitable for that ag demand: Whatcom County, whose mountains (Mt. Baker region) are the most impacted by the lack of aggregate SWE this winter. The Nooksack is a wild river with no reservoirs geologically feasible on any of its forks. So ag in northern Whatcom County is looking to be in for a very rough ride. Lake Whatcom can supply municipal needs for the Bellingham utilities district but is not suitable for the ag in the northern county.

    Do you have a sense of whether groundwater storage of winter excess rain could tide Whatcom ag over the dry season? Or does ag here just need to be "sayonara'ed"? The latter would be a real pity.

    1. This year we either get flooded fields and roads or we're considered too dry. I'm tired of any change in the weather being blamed on "climate change." The climate has always been going through cycles. Improvements in technology have allowed us to have a better understanding of these cycles, but the human impact is such a small drop in the bucket. Unfortunately, our ridiculous media wants to keep us in fear. That's how they get their ratings, and it's one of many reasons I haven't watched the news media in many years.

  4. El Niño certainly explains below average snowpack. But I don't think anyone predicted that snowpack in the Olympics and North Cascades would be approaching values last seen in the notorious 2015 blob year. None of the years with similar snowpack values -- 2001, 2005, 2015 were strong El Niño years.

    So what is unique about this particular strong El Niño?

    1. Joe...well, this is a strong El Nino. And keep in mind that the winter season is not over yet. See the latest forecasts? Substantial snow coming. I suspect we will move closer to normal regarding snow...cliff


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