ST. LOUIS – There are three main things that go into making this winter outlook:
Long range models give us some clues to the long range patternYears with similar patterns, called “analogs,” play a big roleAnd my 30-plus years of forecasting St Louis winters
This year, we are also getting advice from the National Weather Service, which is a partner of ours. There is one main thing that sticks out this year: this is the third winter in a row that we are seeing a La Niña pattern, which is a rarity in itself. We have only had two other triple La Niña winters on record: 1975-76 and 2000-01. This year really favors the 2000-2001 pattern. So with that in mind, here is a look at December, January, and February.
December
This cold wave that blasted into St Louis last week will stick around for a few more days, but will soon leave us for milder air. That trend shows up in the current model runs and in our analog patterns too. And you remember last year? Temperatures in the 60s and 70s off and on all month, including Christmas Eve and Christmas Day! My family opened their presents outside! Warmer than normal also means limited snow chances.
So if we follow our third La Niña pattern trends, here is how December looks: the last two Decembers were dry with below normal precipitation and very little snow. This year will be similar in that there will be some rain events but little chance of snow.
This does not bode well for the chances of a white Christmas. Climate data shows only a 20% chance, and the last time it happened was in 2017. Now, I can’t rule out a rogue storm, but the chances of that are pretty small.
January
If we look at historical data, Januarys are trending pretty cold, and not just our two past La Niña years. I think this year is no exception. We finally will get into some winter cold. This may start to build in late December, but the entire month looks cold, with highs averaging below normal.
As we know, forecasting specific dates for snow events is impossible. But here is a look at what our models and analogs tells us: snow over the last couple of Januarys was minimal and below normal. This year is about the same, with three or four snow events and a total of less than five inches.
Temperatures as I mentioned will be cold; not exactly breaking news for January. But our last two years have trended near normal, and this year we may be a little below that. Average highs will be in the upper 30s.
February
Over the last few decades, February has become the snow month. The yearly trends tell us that there are bigger snow storms in February now than any other winter month. And we don’t have to look far to find proof: the past two Februarys have had above normal snowfall — both equalling over eight inches. February also trends very cloudy and cold, adding to the seasonal depression effects that Linh previously mentioned. It’s the shortest month, but the longest month.
So this February is the snow month again. Last two years, above normal snowfall This year, look for snow in the form of two or even three bigger snow events.
We are also cold again, restating the obvious. The average will be near normal, but with the snow chances, it will feel colder.