We are in a unique time warp. By the time this article is published in the Teton Valley News on Wednesday, we will be seeing the effects of something that is just a forecast at the time of this writing, Sunday, October 6. So if there is no cold snap happening late in the week, just change the title to “Why Did We THINK There Was Going To Be A Cold Snap?”
First of all, what we expect in Teton Valley on a normal October 9 is a high of 41 F and a low of 30. And the coldest it’s ever gotten on record that day is 22 degrees, a record that was set 10 years ago. But this year, the forecast three days out is calling for Wednesday night’s low to be between 9 and 16 above zero in the valley. That’s a forecast of record breaking cold.
But back here on Sunday, why did we think that was going to happen on Wednesday? Part of the answer is that there is above average snow cover in Eastern Siberia. I promise I’m not making this up, although I haven’t been up to Siberia to measure the snow (yet), this comes from our friends at the National Weather Service. Now, by Wednesday, the atmospheric flow is expected to bring down colder than normal air (due to the snow cover) from Siberia to Teton Valley. No kidding.
Luckily, the snow cover doesn’t go all the way from Siberia to Teton Valley or else it would be a lot colder. As the cold Siberian air journeys across Alaska, NW Canada and the Pacific Northwest, it will be able to warm up a little bit thanks to the lack of snow cover and recent sunshine warming the ground. That warmer ground will warm the Siberian air mass during it’s trip which will take about 3 days.
On the weather maps, the leading edge of that cold blob of air will be shown as a cold front. Ahead of the cold front, expect the warmer air to be lifted up by the more dense cold air, form clouds, and start to rain and snow. There will be a lot of wind, too. Behind the cold front, high pressure will bring clearing skies plus that record breaking cold we are expecting. The high pressure represents the center of that traveling Siberian air mass.
So that’s what we expect to happen, but by the time you read this in the paper it will be reality. How’d we do? You can let us know from the future on the Teton Valley Weather Facebook page.