El Nino and Denver’s Winter: Why it’s impossible to predict

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It’s been posted all over news and weather sites for months. It’s been referenced every time that an extreme or interesting weather event has happened. Some tv weather stations have gone as far as to add the adjective “Godzilla” to the the phrase (Which makes no sense to me. I mean really, Godzilla is the king of the Monsters, not some bs makeshift adjective to throw around to make yourself feel important. Don’t sully Godzilla’s good name because you need ratings, gees, but I digress). I’m speaking, of course, of the dreaded EL NINO which is Spanish for….. THE NINO! 

Yes, we are in the clutches of a dreaded El Nino, but what does it mean?! That’s an awfully big question so, I’m going to tackle it in parts below! (if you just want to get down to the nitty gritty Denver details, scroll down to the end)

What is El Nino?

El Nino is a warming of sea surface temperature along the equator to the East of Ecuador, Columbia, and Peru. Below is a map of sea surface temperature anomalies from today (Sept 17, 2015). These anomalies are departures from normal sea temperatures. Over the equator between South American and Indonesia, a belt of warm water can be seen, this is an indication of El Nino.

The warmer sea temperatures and corresponding rainfall from storms shift east towards Indonesia and the Philippines during these times. In addition to largely affecting South America’s fishing industry, El Nino impacts global weather patterns and can vary largely in intensity. The current El Nino is expected to be one of the strongest on record and has a 95% chance of continuing through fall and winter before gradually weakening in the spring of 2016.

Current Sea Surface Temperature Anomaly (Light Blue and Light Yellow are near normal)

Current Sea Surface Temperature Anomaly (Light Blue and Light Yellow are near normal) Click on image for high-res version

“How do you analyze impacts from El Nino?”

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Scales of Analysis

This is where things start to get tricky. As mentioned before, El Nino impacts global weather patterns, there is nothing to debate about that fact. However, when we try to narrow down impacts of El Nino to specific areas like Colorado or Denver, big issues arise in the accuracy of our forecasts. Meteorologists and Atmospheric Scientists use scales of motion to describe weather. We tend to start by looking at the big picture (Global Scale) and then zoom in a bit to an area roughly the size of the US or a continent (Synoptic Scale) followed by zooming in to a local scale such as the Denver Metro area (Meso Scale) and then, possibly, to a neighborhood or specific small area (Micro Scale).

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Water Vapor Image of US at 14:45Z Sep 17, 2015

When we look at El Nino, initially, it’s with a global perspective such as looking at the map of sea surface temperature anomaly above. Obviously, we know that we have a strong El Nino currently taking place and that it is affecting our global weather patterns. Now, we scale it down a bit more and look at the Synoptic scale which is approximately the size of the USA. We can see that El Nino does have some effect on the jet-steams (rivers of high wind speed at high altitudes) and on water vapor transportation, but the extent of these impacts are not known (we just haven’t had enough data and modelling to fully understand them). Now, below the synoptic (USA sized) scale, is when predictions and correlations between El Nino and local weather become very problematic. We know that the Synoptic-Scale weather and the Meso-Scale weather patterns are related and that they influence each other, but if we don’t know the extent of El Nino’s effects on the Synoptic-Scale, we certainly can’t make predictions about its impacts the Meso or Micro-scales. This is similar to the reasoscottyn why, even though there is no doubt that human caused climate change is real, scientists don’t have the ability to make significant predictions about the repercussions other than the fact that we will warm as a planet. WE. JUST. DON’T. HAVE. THE. (computing) POWER!!!! (But, that’s a discussion for another time)

“Yeah Yeah Yeah, but what does it mean for Colorado?”

Trying to predict what winter will hold for Colorado and, more specifically, Denver, when we’re still a couple months away is a very hard endeavor (let’s face it, sometimes we’re terrible at predicting it a few days away). Even with the loads of research that has been done on El Nino as well as the climatologies that have been done on Denver snow storms, we still don’t have a definitive answer to “Does El Nino mean that we will get more snow or a crazier winter?”.

Now, out of the top 10 largest blizzards to hit Colorado, four of them have been during El Nino years. Does that mean that the other 6 were La Nina years? For one of them, yes it was a La Nina year, but for the others we don’t have El Nino/La Nina records for them because they were prior to 1950. In fact, the 7 largest blizzards that do have El Nino/La Nina records, were all during El Nino years, but (and this is important) a sample size of seven events over 23 years of El Nino is NOT incredibly impressive or indicative of large Colorado blizzards being tied to El Nino.

THE BOTTOM LINE

The ultimate take-away from all of this is that we can’t base what our winter will be like on the current influence of the El Nino (Anyone that tells you that a weather event can be attributed to El Nino or climate change is an asshat). It really boils down to what the Synoptic and Meso-scale weather systems do once winter in underway. Could we wind up with an incredibly snowy winter? Yes. Could we have a normal winter? Yes. The Climate Prediction Center has put out it’s seasonal forecast and they have most of Colorado getting above average precipitation and I tend to agree with them based of the moist spring and summer we’ve had, but that can change very quickly. Even if we do have a wet summer it probably won’t be blizzard after blizzard after blizzard (I know, I’m just as disappointed as you). It will more than likely come in the form of an extra storm or two every month. Only time will tell and as soon as the fluffy stuff is in the forecast, I will start to be more brazen about forecasts (And more active on here. Late summer weather is BORING!). So, keep in touch and visit when possible and I will keep you updated!

Cheers!

-Andrew

Let me know what you think about this post! I would love to get some feedback on how it was to read and what you did/didn’t like about the content!

El Nino/Snow/Prediction Websites-

El Nino Discussion

El Nino and La Nina Years

Denver’s Historic Blizzards

Climate Prediction Center

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One thought on “El Nino and Denver’s Winter: Why it’s impossible to predict

  1. Overall, this is a great read! Only two detractors in my mind:
    El Nino vs. El Niño: Alt+164 is a quick and easy way to insert “ñ”.

    Always like your posts. Keep up the good work!

    Like

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