All Weather News

Developing El Niño Pumps the Brakes

11 Jul 2014, 1:37 pm

Since early this year you’ve probably been hearing about the likelihood of El Niño developing by late fall or early winter; potentially bringing some much needed drought relief to the western U.S. But in recent weeks the rate of warming in Pacific equatorial waters has slowed dramatically. So does that mean the potential El Niño is dead? Not according to a recent analysis by scientists at Columbia University. More on that in a bit.

First, lets get a little info on El Niño:

El Niño is the abnormal warming of equatorial waters in the Pacific Ocean. Normally, waters off the western coast of South America are cool — due to upwelling of deep, cold ocean currents. But during an El Niño the trade winds relax, allowing warmer waters to shift east. This shift in wind patterns and water temperature also instigates a big change in tropical pressure patterns — called the Southern Oscillation. Lows that once formed close to Australia and Papua New Guinea are now more prevalent in the central Pacific.

neutral
Image Courtesy: climate.gov

The image above shows ENSO during a neutral phase. Note the convection over the western Pacific and a strong high pressure in the eastern Pacific.

elnino
Image Courtesy: climate.gov

The image above shows ENSO during a El Niño phase. Notice the shift of convection the central equatorial Pacific and high pressure in the western Pacific.

At present, the average sea surface temperature anomaly is about 0.5°C and that’s at the precipice of declaring an El Niño. So…Why hasn’t it been declared? Well, here’s the short answer: The atmosphere hasn’t responded to warming waters in the tropical Pacific. At present, the trade winds haven’t relaxed and the typical shift of pressure hasn’t occurred, couple that with a slight downtrend in sea surface temperature anomalies, scientists have elected to hold off on calling the current setup an El Niño.

Be that as it may, models and the scientists that analyze ENSO data still think there’s a high likelihood that an El Niño will be in full bloom by late fall to early winter. A recent analysis from researchers at Columbia University suggests there’s an 80 percent chance of El Niño by October or November

models
Image Credit: Columbia University/IRI/CPC

So even though the warming has stagnated, climate models are generally in agreement that additional warm temperature anomalies are likely. The extent of the warming is still a bit murky.

If El Niño does develop it’s likely to be welcome news for many that live in the western, drought-stricken parts of the United States. As of early July large parts of California and Nevada are dealing with extreme to exceptional drought conditions and it’s unlikely to get better through the summer and early fall.

drought

However, during an El Niño period, the West Coast and parts of the Southwest are more likely to be much wetter than average. If it comes to fruition, El Niño could help ease the drought conditions in those areas.

Much remains to be seen, but the WeatherNation team will be monitoring the latest ENSO news in the coming months.

Meteorologist Alan Raymond

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