El Nino expected to develop, could dramatically impact winter in Metro Detroit

Implications for our winter ahead could be significant

By Paul Gross - Meteorologist

DETROIT - NOAA’s Climate Prediction Center issued an El Nino Watch this afternoon, highlighting the potential for another El Nino to develop in the months ahead. This could dramatically impact our winter, as I’ll explain below in a moment.

But first, a lot of people don’t understand what an El Nino (and it’s sister, La Nina) are and how they affect our weather. As you can imagine, the surface waters of our world’s oceans do not have the same temperature -- there are differences.

In the Pacific, when prevailing winds push its warmer surface waters eastward, it’s called an El Nino.  When those winds reverse and push those warmer surface waters westward toward Asia, it’s called La Nina.

So what’s the big deal about this? Because there is a tremendous interaction between our oceans and the atmosphere -- more thunderstorms form where those warmer waters are, and that impacts the jet stream configuration. And, as we’ve explained many times in the past, the jet stream not only separates generally cold air masses from warmer ones, but it’s also our general storm track.

In an El Nino winter, two things happen: The main Arctic jet stream tends to shift farther north, which limits Arctic air intrusions into our region. That means more (NOT all, but more) of our winter precipitation falls as rain, rather than snow.

But the farther north storm track also sometimes gives us a drier than normal winter. El Ninos also strengthen the subtropical jet stream, which creates a more persistent storm track across the south, and gives them a cooler, rainier winter in general.

In a La Nina winter, the Arctic jet stream trends farther south, allowing more Arctic blasts into the Great Lakes. If the storm track is near us, that means more snow storms.

Farther south, the subtropical jet stream is almost non-existent, so they have a drier, sunnier, more pleasant winter. If you’re a snowbird, you like La Nina winters.

Here is the latest Climate Prediction Center temperature outlook for the three-month period from January through March:

Here is the latest Climate Prediction Center outlook for precipitation for the three-month period from January through March:

Based upon what I explained above, you can easily see the El Nino influence on our general weather pattern across the country.

Another important impact from El Ninos and La Ninas are their respective impacts on hurricanes. El Nino patterns generally create more wind shear in the Atlantic basin, and that means less favorable conditions for hurricane development.

The developing El Nino could diminish this fall’s hurricane season, but remember: all it takes is one bad storm to hit a highly populated area, so don’t let your guard down if you have family, property, or travel plans this fall to the southeast.

La Nina patterns generally lessen the wind shear in the Atlantic basin, which favors more hurricane development.

While there is reasonable confidence in an El Nino developing this fall, we’re still several months away, and this could still change. We’ll keep a close eye on things, and update you on-air, on social media, and here on ClickOnDetroit.

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