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Is El Niño coming? What does it mean for Virginia?

ElNinoWatch

RICHMOND, Va. (WTVR) – Even though it feels like we’ve just finally started Spring, we are already monitoring something heating up in the Pacific Ocean that could impact us later this year. We are on El Niño watch!

As of the April 7 update from the Climate Prediction Center, which tracks ocean temperatures in the equatorial Pacific, we are in “Neutral” phase of the El Niño-Southern Oscillation (ENSO). Maybe you’ve heard this called “La Nada,” because nothing of particular interest happens in this part of the Pacific Ocean when sea surface temperatures are near-normal.

But what happens in this zone can have tremendous impact on global weather patterns. That impact is most-felt in North American Winter. Here’s what El Niño and La Niña do to our weather patterns:

nawinter

So where are we right now? Neutral. La Nada, sure. But we are watching something…

ElNinoWatch

The trend in recent weeks has been for slightly warmer-than-average waters in this key ENSO zone. Look west of South America around the equator for the area highlighted in yellow on the map above. Technically, the warmer temperatures are still “near-normal,” but the trend is warming. Watch this animation of the anomalies in that zone changing from light blue (cooler-than-average) to yellow and orange (warmer-than-average) since January:

sstaanimAnomalies

And it’s not just our weekly observations hinting at signs of developing El Niño. A swarm of reliable computer models are in decent agreement that El Niño (warmer-than-average conditions in the eastern equatorial Pacific Ocean) will form sometime this Summer or Fall 2014.

SSToutlook

The consensus is stronger the later in 2014 we go.  If we look at this through the lens of probabilities, that puts us at a 50% chance of El Niño developing in the Summer or Fall of 2014:

50percentchance

So what would El Niño conditions thousands of miles away from Virginia have to do with us?

The timing of this potential El Niño is crucial. In North America, Winter months are when we most “feel” the impact of El Niño or La Niña (as shown in the first graphic at the top of this article).

But because this watch focuses on Summer into Fall, not Winter, let’s pick the three-month period of September-October-November, and see what that could mean for the U.S. Here’s the climatology of what El Niño does for temperatures across the country:

elnino.son.temp

When you factor in the overall warming of the climate, plus El Niño, the result (the two maps on the bottom) shows central Virginia late Summer-Fall can be a little warmer-than-average when El Niño occurs. But that chance of us being a little bit warmer because of El Niño is very low (less than 30%). In fact, El Niño has very little to do with us having gradually warmer late Summer-Fall months. It’s climate change (the middle map “Trend”) that shows a gradually warming central Virginia.

Now let’s look at the climatology of what El Niño does for precipitation across the country during that same three-month window:

elnino.son.precip

Again, we see that central Virginia is trending toward a wetter-than-average late Summer-Fall over recent decades, but it is likely not because of El Niño conditions. It is, again, because of climate change in our region.

Let’s play a game of “What if?” What if El Niño does develop before Winter 2014-2015? What if it’s a strong El Niño? Even then in central Virginia, there is no clear sign saying we’ll have any greater chance than usual of a drier/wetter or warmer/colder winter. El Niño’s winter impact on us in central Virginia, specifically, appears to be nada. But what is clearly impacting us in central Virginia over time is climate change. And that is a trend scientists worldwide are monitoring.

Meteorologist Carrie Rose
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