How Will La Nina Affect Winter Weather?

How Will La Niña Affect Winter Weather?


A weak La Niña continues to impact North America


Looks Like Another La Niña Winter

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According to early reporting, it looks like we're in for another La Niña! What does that mean? How will La Niña affect your winter?

As one of the main drivers of weather in the U.S. and around the world, La Niña affects your lives from winter snow to grocery bills. Let's review . . .

What is La Niña?

Warmer or colder ocean temperatures in one part of the world influence weather around the globe. Boggles the mind, right? The temperatures may be only 1 degree warmer or colder than average, but these deviations cause large-scale impacts on global weather and climate.

  • A La Niña year occurs when there are abnormally cool water pools along the eastern Pacific. A typical La Niña winter brings dry conditions (and sometimes drought) to the southern tier of the U.S.; conversely, it brings cold and wet conditions (and sometimes heavy flooding) to the Pacific Northwest. Wet conditions in the North can also bring lots of snowstorms in the Great Lakes, extending into the Ohio Valley. The Southeast and Mid-Atlantic also tend to be drier and warmer than average during a La Niña winter. 
  • Conversely, waters are unusually warm in an El Niño year. This leads to possible flooding in the southern U.S. and wetter-than-average conditions over parts of the Gulf Coast and Florida, while drier-than-average conditions can be expected in the Pacific Northwest and Canada.

Learn more about La Niña and El Niño.


A New Style of Reporting La Niñas

NOAA tracks the sea surface temperatures in the middle of the Pacific ocean. See below. (Specifically, scientists measure the area known as the Niño 3.4 region, which is located from 120°W to 170°W.)

La Niña (and El Niño) episodes typically last 9 to 12 months. In the past, mainstream media would typically not report on La Niña or El Niño activity until the fifth or sixth consecutive month of the temperature anomaly. This meant that areas in North America would have been unaware that they were expecting El Niño or La Niña conditions.

When reporting is delayed for many months, it arrives almost too late to determine systems' impact on global weather and climate—which affects our lives, work, and other factors such as severe weather preparedness, food production, water supply, and even human health. With many industries needing to know the weather’s impact on their bottom line, the lack of El Niño/La Niña news was becoming financially problematic.

That was then; this is now: After only 3 months of eastern Pacific temperatures averaging 1 degree below the norm, Internet and mainstream news sources around the Internet have begun reporting—forecasting!—a La Niña winter.

La Niña 2017 Early Predictions

This is the second consecutive La Niña winter. Last year's episode was atypically short, forming in November 2016 and gone by February 2017. 

NOAA’s attempt to become proactive about conditions this fall/winter has given all of us more time to prepare. For example, a strong La Niña is often bad for agriculture in southern regions, and U.S. production of most crops—except corn—generally goes down in La Niña years.

Fortunately, it seems that the upcoming La Niña of 2017–2018 is going to be weak and relatively short-lived, too. The equatorial waters of the eastern and central Pacific are only slightly cooler than usual, which means that the effects of La Niña are expected to be weaker. 

Whether the NOAA predictions are correct remains to be seen. Still, this is an intriguing time for weather reporting. If this is the new normal—with conditions reported earlier—we will all be better able to make timely preparations.

Read more about the world of Teleconnections and Oscillations.

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