The effects of La Niña events vary widely by region, even within the United States. Here’s what winter weather means:
Climate change troublemaker La Niña will dominate winter weather in the United States, federal forecasters at the Climate Prediction Center announced Thursday, Nov. 13.
“La Niña conditions have persisted over the past month, as evidenced by below-average sea surface temperatures in the central and eastern equatorial Pacific,” the prediction center said in a statement.
La Niña is part of a natural climate cycle officially known as El Niño Southern Oscillation, which scientists refer to as ENSO. This cycle moves back and forth between warm and cold ocean water in areas along the equator of the tropical Pacific Ocean. La Niña is characterized by lower than average seawater levels in the region.
These subtle changes can have large ripple effects across the Earth’s climate, increasing the likelihood of rain, drought, hurricanes, and other disruptions in cycles. Even within the United States, the impact varies widely by region.
Although on the weak side, federal forecasters say the La Niña event will still be the main driver of winter weather in the United States.
That impact is likely to be strongest during the winter months, which is why it plays a large role in the CPC’s recently released winter outlook, John Gottschalk, director of operational forecasting at the Climate Prediction Center, told USA TODAY.
La Niña events also increase hurricane activity in the Atlantic Basin. Fortunately, hurricane season is almost over, so there shouldn’t be any effects from La Niña this year.
Does La Niña mean winter weather? The map shows a typical pattern.
What is La Niña?
La Niña is part of a natural climate cycle officially known as El Niño Southern Oscillation, which scientists refer to as ENSO. This cycle moves back and forth between warm and cold ocean water in areas along the equator of the tropical Pacific Ocean. La Niña is characterized by lower than average seawater levels in the region.
This is one of the main factors that determines the weather in the United States, especially in late fall, winter, and early spring. This is the opposite of the better-known El Niño, which occurs when Pacific water temperatures are at least 0.9 degrees warmer than average for three months.
The intermediate stage is known as ENSO-Neutral, where neither La Niña nor El Niño exists.
What’s the winter forecast?
According to CPC’s winter forecast, California, much of the East Coast and Florida, as well as the southern United States, will most likely experience a warmer-than-normal winter. Colder-than-average conditions are expected across the Pacific Northwest and upper Midwest.
When it comes to snow and rain, the northern Rocky Mountains and Great Lakes region are most likely to see the most precipitation this winter, the Climate Prediction Center said. However, a drier-than-normal winter is expected in the southern tier of the country, especially in the southeast.
The center’s forecast covers the months of December, January and February, known as meteorological winter months.
What other factors are at play?
AccuWeather’s recent U.S. winter forecast also points to La Niña as one of the key factors for next season, said Paul Pastelok, AccuWeather’s senior meteorologist and long-range expert. He said in an online forecast that La Niña conditions are likely to influence snow, rain and temperature trends across the country, but stressed that this year’s La Niña appears to be weak, leaving room for other oceanic factors to influence the forecast.
One of those factors is a marine heatwave that stretches across much of the North Pacific Ocean from Japan to the U.S. West Coast.
“These areas off the West Coast and beyond are very, very important in this year’s (winter) forecast,” Pastelok explained. He added that there have been few winters in recent decades with similar conditions over such a vast ocean area.
Why are La Niña forecasts important?
“Seasonal forecasts of El Niño and La Niña and their associated climate impacts are important climate information tools,” World Meteorological Organization Director-General Celeste Sauro said in a recent statement.
“These have led to millions of dollars in economic savings for key sectors such as agriculture, energy, health and transportation, and have saved thousands of lives when used to guide preparedness and response actions,” she added.
