What does El Niño Watch mean for Atlantic hurricane season, US winter?

With the issuance of an El Niño Watch, many may be wondering what implications that can have on the weather that affects the United States.

A June 14, 2018, report from NOAA’s Climate Prediction Center (CPC) stated that there is a 50 percent chance for El Niño to develop during the fall (starting with the months spanning August to October).

That percentage is forecast by the CPC to increase to around 65 percent during the winter of 2018-19.

El Niño occurs when water temperatures across the equatorial Pacific Ocean rise above normal for an extended period of time. The opposite effect of cooler weather over a similar time period is known as La Niña.

The AccuWeather Long-Range Forecasting Team agrees with the CPC’s predication that the pattern will trend toward El Niño in the fall and continue into the winter.

Latest indications point toward the upcoming El Niño being weak, but a moderate El Niño developing cannot be ruled out. At this time, a strong El Niño is not anticipated.

El Niño can have implications on the weather across many parts of the globe depending on its onset, strength and duration. This includes the Atlantic hurricane season and the winter across North America.

Implication of El Niño on the Atlantic hurricane season

While this year’s Atlantic hurricane season started early with Alberto, El Niño may keep the number of named storms near to below normal.

Due to the anticipated onset of El Niño, AccuWeather Hurricane Expert Dan Kottlowski stated that a much less active season can unfold.

"Typically, the season also tends to end earlier," Kottlowski stated. November 30 marks the official end to hurricane season.

However, Kottlowski stressed that residents in hurricane-prone areas should not let their guard down given the above information.

"We could still end up with storms later in August into September, as that is an active time of the year," he said. "In addition, the season could end below normal, but the strength of the storms is still something to worry about and how that translates to impacts to land."

It only takes one tropical storm or hurricane to devastate an area with flooding rain and/or destructive winds.

How El Niño could impact the upcoming winter for the US

The anticipation of El Niño can give a glimpse into how the weather may unfold across the United States during the 2018-19 winter, but this is not the only factor used by the long-range forecasting team.

"Sometimes an El Niño of the magnitude that we are expecting can cause stormy weather in the eastern U.S.," according to AccuWeather Senior Meteorologist Bob Smerbeck.

"If the El Niño develops, there is a higher probability of closer-to-normal rainfall in the southern Plains," AccuWeather Senior Agricultural Meteorologist Dale Mohler said. "That could bring a better start to the winter wheat crop than last year."

However, the onset of El Niño does not guarantee a repeat of what transpired during previous El Niños.

"Not all El Niños are the same and other natural climate phenomenon can also interact with El Niño, resulting in a wide variety of seasonal impacts across the globe," AccuWeather Senior Meteorologist Brett Anderson said.

That was clearly evident in Southern California during the winter of 2015-16 amid one of the strongest El Niño's recorded since 1950.

An El Niño typically leads to more storms targeting California, but other factors came into play that winter and Downtown Los Angeles ended the rainy season with less than 65 percent of normal rainfall. Only 0.79 of an inch of rain was measured during February 2016.

February 1998 remains the wettest February on record for Los Angeles with 13.68 inches. This occurred during a similarly strong El Niño.

The AccuWeather Long-Range Forecasting Team will take all climate phenomenon into account prior to releasing the official 2018-19 U.S. winter forecast in October.

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