Dreaming of a white Christmas? El Niño might want a word with you

More often than not, we pull off a white Christmas in the Twin Cities. This year, though, we’re in an El Niño weather pattern, which creates mild winters, and we’ve been lacking for snow so far this season. Forecast models don’t offer much hope for a holiday snowpack.

Dry year continues as fall turns to winter 

This year will be remembered for many things meteorologically, but the drought will surely be near the top of the list.

While we received some beneficial, soaking rains for a few weeks in late September to mid-October, that wet pattern left as quickly as it came. November saw just four one-hundredths of an inch (.004) of precipitation the whole month. Half of that liquid fell as snow. 

We saw a whopping one-half inch of snowfall the whole month, which was outdone by Monday night’s nearly 1 inch of snow.

Most of southern Minnesota has seen a tiny fraction of normal snowfall over the past 30 days. Even northeastern Minnesota has seen less than half its normal snowfall.

On top of the just dry pattern, temperatures have also been very mild, which can also contribute to a lack of snowfall if ever we get the chance. 

‘Super El Niño’ could worsen lack of snow

On top of warm temperatures and a very dry pattern we have a very strong El Niño in the mix. That could exacerbate problems caused by a lack of snow. 

El Niño is expected to become even stronger heading into midwinter, potentially at “Super El Niño” levels. 

I analyzed snowfall over El Niño episodes back to 1950 in the Twin Cities and snow cover for Christmas Day in those years as well. In that 72-year period we had 25 El Niño episodes. Winter seasonal snowfall in an El Niño winter averages about 23 percent less than in a normal winter (40 versus about 52 inches).

On top of that, since El Niño winters average about 2 or more degrees above normal, we see several (4 to 6) more thaw days on average. Those factors combine to create less snow pack.

What about a white Christmas? 

Every year we get bombarded with questions about a white Christmas whenever we head into this two to three-week period before the holiday. Usually at this point I tell people not to worry, a lot can happen in Minnesota weather in a two to three week period in winter! 

The correlation between snow cover on Christmas and El Niño winters was even more pronounced than I anticipated: 56 percent of El Niño winters saw a brown Christmas.

A white Christmas is defined as 1 inch or more of snow cover. In those years we pulled off an official white Christmas more often than not it was barely. 64 percent of El Niño Christmases had just 1 inch or less of snow depth. 

In a normal winter, we can expect a white Christmas 74 percent of the time climatologically in the Twin Cities. El Niño more than doubles our odds of having a brown Christmas. 

It appears that the overall warmer winter temperatures help cause a late start to winter, something that has been exacerbated by climate change. December is one of our fastest warming winter months in recent decades. 

If we step away from climatology and just look at what our forecast models say, it doesn’t offer a lot of great hope either.

Below are two long-range ensemble models, which are many different runs of models tweaked and averaged together to make for a less chaotic longer range forecast. Both models only yield a few inches of snow over a 16-day period.

Almost all of the models keep temperatures above normal during this period, which means if we do get lucky with a smaller snowfall, it potentially would melt anyway.

To come full circle however, I have to stand by this point: Weather in Minnesota can change on a dime, so don’t give up hope on significant white stuff just yet.