Friday, November 13, 2015

We are subject to a pretty strong El Niño year

(Photo: Courtesy of Jason DeBoer)
by Chris Bonanno:

You've undoubtedly heard by now that we're subject to a pretty strong El Niño year in Brevard and that with that comes wetter, cooler weather with an increase in chances for severe weather and tornadoes.

For those who aren't aware, El Niño is the warming of the equatorial waters in the Pacific Ocean that occurs every several years or so.

But the question is this: How does the warming of waters thousands of miles away from Brevard impact us?

The real answer lies with the positioning of the jet stream, according to Scott Spratt, warning coordination meteorologist with the National Weather Service in Melbourne.

He says El Niño causes the jet stream over North America to shift south. When that happens, the jet stream brings in more low pressure systems and accompanying cold fronts that can produce showers and thunderstorms.

Spratt explained how El Niño acts as an enabler of the inclement weather.

"The waters across the eastern Pacific usually are very cold and very stable, somewhat like along the coast of California but even colder and even more stable along the coastline of South America during a non-El Niño year. So an El Niño year replaces that very cold and stable water with the very warm water," said Spratt.

He continues, describing how the storms develop over the warmer water and how that sends the jet stream further south.

"Above the warm water, thunderstorms develop just like thunderstorms develop over warm land and then when the thunderstorms develop now you get a feedback from the ocean to the atmosphere, so now the atmosphere is being impacted and by having all the thunderstorms releasing the energy across the eastern Pacific Ocean, it's causing a change in the jet stream and it's driving a stronger jet stream across a lower latitude," said Spratt.

"There's times when we still have the jet stream up across the northern latitudes but a second jet stream will develop and this jet stream's called the subtropical jet stream so here's our main jet stream and our subtropical jet stream develops because of that warm air associated with the thunderstorms above the warm water caused by the El Niño," he added.

The jet stream moving south across North America doesn't just impact us either, he noted. It forms around Hawaii and streams through California and Florida in what some call the "Pineapple Express." With much of California facing extreme drought conditions, such a pattern might be beneficial to them.

Although we haven't felt it yet, every indication is that this will be one of the strongest El Niño years on record.

So now, when it happens, you'll know how.
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