Probability forecasts are used to predict El Niño-Southern Oscillation (ENSO) conditions because there are so many intricate climate variables that affect the final outcome.
© NOAA

While it is still way too early for an accurate prediction for Winter 2021-22, conditions are forming that could deliver cold and snow this season.

In early July, the Climate Prediction Center (CPC) issued a La Niña Watch for the September-November fall season and lasting through the 2021-22 winter season. The La Niña watch calls for a 66 percent probability that La Niña emerges by November to January. This is a greater probity than last year’s 50-55 percent chance.

Probability forecasts are used to predict El Niño-Southern Oscillation (ENSO) conditions because there are so many intricate climate variables that affect the final outcome.

Winter 2020 temperatures compare against Winter 1981 temperatures. Upper Right: A moderate to strong La Niña, historically, would suggest a cool and wet winter across the northern U.S. and a dry and warm winter south. Bottom Right: Last year, the snow belt received the following seasonal accumulations as compared to normal.
© NOAA

So, what happened with last winter’s La Niña? A moderate-strength La Niña did, in fact, emerge as expected during the fall and winter months of 2021-2022, but the meteorological effects on the United States’ weather was not what we’d normally expect.

As we have written about in past articles, La Niña years typically bring colder and wetter than normal conditions to the northern United States, with drier and warmer conditions to the south. Last winter, however, above normal temperatures were observed nearly nation-wide during December and January, with the absence of a true winter chill until a Sudden Stratospheric Warming event occurred in February, ushering in record cold, and shutting down the Texas power grid.

© THERMODYNAMIC SOLUTIONS

Climate scientists at the CPC noted that this event was the least La Niña-like pattern of 13 moderate to strong La Niñas dating back to 1950. Observed precipitation was closer to the expected La Niña pattern, though.

© THERMODYNAMIC SOLUTIONS

Last year, the snow belt received the following seasonal accumulations as compared to normal.

Recent ENSO observations suggest we are in an ENSO-neutral-cool phase, which does not strongly support atmospheric or oceanic impacts from either La Niña or El Niño. Sea surface temperatures in the Equatorial Pacific are expected to rapidly fall beginning in late July and continue to cool through the late fall and winter months.

With that, another moderate to strong La Niña should develop. Once again, historically, this would suggest a cool and wet winter across the northern U.S. and a dry and warm winter south. It is much too early to put out winter predictions for snowfall at this point, though.

Beth Carpenter is a co-founder and meteorologists at Thermodynamic Solutions. She is a frequent Snow Magazine contributor.