Erica Grow Cei: Will the return of El Niño mean the return of snow?

Last winter was a disappointment for snow-lovers in the Tri-State area. Though it snowed several times, including a bunch of trace amounts, we ended up with a grand total of 2.3"of snow in Central Park. Last year at this time, we were in La Niña, or the cold phase of ENSO. Now that the pattern has flipped to El Niño, or the warm phase, the outlook for our upcoming winter is quite different. Whether it results in a larger snow total remains to be seen.

If you use the Farmer's Almanac to help plan your winter, I have bad news for you: It's already wrong about this year. The Almanac's winter forecast says, "snow will arrive beginning in November" in the Tri-State area. You're probably aware that we have yet to see a single flake of snow. This is true not only in NYC, but throughout the entire region. Whoops!

Only time will tell if the Farmer's Almanac forecast for "oodles of powder" pans out

for the Northeast and Mid-Atlantic.

As Yogi Berra famously said, "It's hard to make predictions, especially about the future". Boy is this true when it comes to seasonal snowfall forecasting. Keep in mind that the snow-to-rain ratio is usually about 12:1; that means foot of snow melts down to about an inch of rain. Add up an entire season of snowstorms, and the margin for error is as wide as the Hudson. But, there are insights we can gain from our current pattern- insights that could be more valuable than a prediction for the number of inches of snow we'll see this year.

In the Northeast, La Niña winters tend to be drier, whereas El Niño usually brings more precipitation. But that doesn't mean all El Niño winters are snowy in the Tri-State area!

Above is a list of the snowiest seasons ever recorded in NYC on the left, with the least snowy on the right. The snowiest winter of 75.6" occurred during El Niño. The third-snowiest, at 61.9", was during a strong La Niña. And #6 on the least snowy list was also a Super El Niño year! While knowing the ENSO phase doesn't help us figure out how many inches of snow we'll get, it can offer valuable insight to the winter ahead.

La Niña winter conditions are more favorable for two types of snowmakers: Alberta Clippers and Four Corner Low pressure systems (often called "Colorado Lows"). Even if you're not familiar with the term Alberta Clipper, you probably know what they feel like: a little bit of powdery snow followed by an Arctic blast. Clippers usually bring 3" of snow or less to the Tri-State.

Source: NOAA's Weather-Ready Nation Infographics Page

A Four Corners Low is so named because it originates in the Rockies, near the "Four Corners" region where Colorado, New Mexico, Arizona, and Utah meet. After exiting the Rockies, their trajectory often leaves the snowy side of the storm to our north, leaving us with slush or rain- but not always.

Source: NOAA's Weather-Ready Nation Infographics Page

In an El Niño winter, coastal systems like Nor'Easters are more common and more frequent than the Clippers and Colorado Lows described above. These coastal storms draw more water from the Atlantic Ocean than their continental cousins, bringing heavier precipitation to the Northeast and Mid-Atlantic. And if it's cold enough when the Nor'Easter arrives, we could have a major snowstorm on our hands.

Source: NOAA's Weather-Ready Nation Infographics Page

Such was the case during the record-breaking snowstorm of January 2016. We were in a "Super El Niño", with temperatures way above average in the equatorial Pacific. After a record-shattering warm December, it finally got cold in the Tri-State by the second half of January. The environment was primed and ready to turn a disturbance in the Gulf Coast into a raging blizzard.

Graphic (above) and map (below from NWS Upton, NY)

When making a forecast for an entire winter season, meteorologists look for analogs, or similar atmospheric setups. ENSO is one factor, but other patterns such as the North Atlantic Oscillation play a role. So does the supply of cold air upstream from the Tri-State, even as far away as Siberia.

So here's what I'm thinking:

In a year with a strong El Niño like this one, it's more likely that the entire season's snow will fall in a couple of big storms, rather than us having to deal with several "nuisance" snowfalls.
In most NYC winters, we don't need to break out the shovel until after the New Year. But this winter, a plowable snowfall is likely before Christmas- maybe even before the final night of Hanukkah!
This winter's pattern is NOT conducive to a big, damaging ice storm. Hooray!
This pattern is also NOT favorable for a nasty March (remember in 2017 when we dealt with four consecutive snowstorms?) Double Hooray!