Santa Bringing Bagful of Cold and Snow – Just in Time, But Where?

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On the other side of the equator, Christmas is a summer holiday. In Australia, it’s quite normal for Santa to arrive on a surfboard (more about Christmas “down-under” here), but I think we on this side of the equator agree that colder is better and cold with snow is best. If that’s your idea of Christmas, then prepare yourself for a happy upcoming holiday. And although that’s a rather broad promise, it does look like an outbreak of substantial cold will combine with the possibility of significant snowfall from North Texas and the Plains and over to the Great Lakes right around Christmas Day and mid-week, next week.

Though the first signs of this approaching cold pattern were evident about a week ago, we (ImpactWeather’s StormWatch team) wanted to make sure there was some legitimacy to those early signs. By this past Friday, we thought there was growing confidence to at least begin hinting that something was  possible (read Friday’s YourWeatherBlog post here). Now, three days later, our confidence continues to grow. Here’s the latest from ImpactWeather’s StormWatch manager, Fred Schmude:

The Christmas Day forecast has changed slightly since last Friday’s forecast, but the overall pattern remains the same: colder air plunging southward east of the Rockies combining with a storm system in the central Plains. Image: ImpactWeather

“It’s a classic front runner on the lee of the Rockies with cold air wedging southward near or just after Christmas Day. This, combined with a pre-frontal storm later this week dropping 4-8” of snow from Kansas over to Michigan means we could have decent snow cover all the way south to the northern Oklahoma border. It looks like the front is a certainty, I’m still uncertain about the timing. We could easily see two distinct blasts of cold air between Christmas and New Years Day.” How much of this cold air reaches the Gulf Coast is still in question, but Fred feels it could be significant.

We’re still relying heavily on the computer models at this early stage. As with a hurricane forecast, confidence in the numerical prediction models grows when more of the models swing to a consensus or near-consensus. And that’s especially true when the strongest models, in this case the GFS and the Euro, are in agreement. Specifically, the Euro hit on the cold first and the GFS has been playing catch-up, but here we are about a week out, and the two are in agreement.

As for snow, it indeed does look like there could be a snowstorm mixed in with all this cold weather. And timing looks like it will be ideal, if you like your Christmases white and you live in the middle of the U.S. However, unlike the cold outbreak, there still remains significant differences between the models as to the critical questions of where, when and how much. Not only are the models differing between each other, they’re taking the differences right to their own backyard and differing between each 12-hour run of data. For now, significant accumulation looks possible in Oklahoma with lesser amounts of perhaps a couple of inches in Kansas to the north and perhaps as far as Dallas to the south. Additionally, significant snowfall is possible in Wisconsin and Minnesota.

Captured early on Christmas morning, the warm temperatures are still well-entrenched along the Gulf Coast. However, it’s easy to see the significantly colder temperatures across the central and northern Plains. The storm system moving across Texas, with its counterclockwise flow, will help pull these temperatures southward on the 25th and 26th. Image: ImpactWeather

We should also consider the possibility of severe thunderstorms as this frontal system pushes into the warm, unstable air lying ahead of it. Already temperatures are well above normal from Texas to Georgia to North Carolina and this trend should continue for the next several days. Undercut that air mass with a significantly colder one from the north, and combine it with the decidedly colder air aloft and severe thunderstorms are all but inevitable.

If you had your druthers, would you prefer that Santa arrive in swim trunks and on a surfboard? Or would you prefer the red suit, sleigh and reindeer? I probably don’t speak for many, but I know here on the Gulf Coast we prefer our St. Nick in a sleigh and we want only one day of snow and cold each year: December 25th. Our friends farther north likely expect it to be cold and snowy on the 25th and are disappointed when that doesn’t happen. It certainly looks like many will get their wish come Christmas Day, but at this time it’s still too early to be totally committed to the definitive “where, when and how much.”

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