Forecasters Warn El Niño is Likely This Summer. Here's What That Could Mean for the Midwest

After two straight years of La Niña , the National Weather Service has warned that conditions are likely for an El Niño to develop in the coming months — and that could have some big implications.

The agency issued a watch in April, meaning “conditions are favorable for the development of El Niño within the next six months,” adding that there is a 62% chance those conditions will develop sometime between May and July.

Should those conditions develop, it could mean changes in weather and climate patterns across the U.S. and even around the world, experts say.

In an El Niño event, a band of warmer-than-normal water develops in the central and east-central Pacific Ocean.

High pressure tends to dominate weather patterns in the western pacific and low pressure patterns dominate in the eastern Pacific, which in turn causes more frequent rain events, which can impact California with heavier-than-normal rainfall. In addition, the jet stream from the Pacific pushes that extra rain across the southern United States, making for wetter-than-normal conditions in the desert southwest, in Texas and in states around the Gulf of Mexico.

With the Arctic jetstream typically ranging further to the north, warm air typically rushes into the northern United States, including parts of the upper Midwest.

The Midwest also sees drier-than-normal conditions in most El Niño years, as do parts of the eastern United States.

Typically those impacts aren’t felt until the fall, since El Niño’s primary impact comes during the winter, but in some years the pattern is strong enough that it begins to exert influence during the summer months.

The World Meteorological Organization put out a warning Wednesday, saying “the likelihood of El Niño developing later this year is increasing.”

“This would have the opposite impacts on weather and climate patterns in many regions of the to world to the long-running La Niña and would likely fuel higher global temperatures,” the alert states.

According to the WMO, the likelihood will increase to a 70% chance between June and August, and up to 80% for July through September, though the strength and timeline of the predicted change remain uncertain.

“We just had the eight warmest years on record, even though we had a cooling La Niña for the past three years and this acted as a temporary brake on global temperature increase. The development of an El Niño will most likely lead to a new spike in global heating and increase the chance of breaking temperature records,” WMO Secretary-General Prof. Petteri Taalas said in a statement. “The world should prepare for the development of El Niño, which is often associated with increased heat, drought or rainfall in different parts of the world. It might bring respite from the drought in the Horn of Africa and other La Niña- related impacts but could also trigger more extreme weather and climate events.”

But experts stress that no two El Niño events are the same and the impacts will depend largely on the time of year it develops.

from NBC Chicago https://ift.tt/NWViL3f