Weather Blog: An unusual chance of snow on Wednesday

Wednesday's Chance Of Snow
Posted at 7:37 AM, Feb 09, 2021
and last updated 2021-02-09 10:44:26-05

Good morning bloggers,

We are in a possible record-breaking longest stretch of cold under 20 degrees in KC. We will discuss what is causing this; how long it will last; and the chances for snow.

What is causing the Arctic Outbreak?

In our winter forecast, we predicted that there would be one of these long stretches of brutal cold and winter weather if the AO dipped deep negative. It almost did it a few weeks ago, but it fell just short, and the Arctic air was stuck over Canada. As a result, the first 90 days of this year's LRC (the cycling weather pattern) has been warm. Look at the past 90 days:

Precipitation & Temperatures Last 90 Days

It had been a very mild winter over the past three months. And then this happened in the past two weeks:

Block In Canada

This is the second blocking upper high that has formed in this season's weather pattern. A weaker version of this blocking high formed a couple weeks ago, and it was followed up by this one right now. There is a big block over northern Canada, and this is moving west in the Polar Easterlies. It is forcing the Polar Vortex to shift south toward the United States. It has resulted in the Arctic blast, and strong surface high-pressure areas over Canada that are now heading south into the USA. There is a good chance Kansas City will drop to way below zero in the next week, and there are chances of snow.

How long will this last? Once the Arctic Air reaches the USA, we need something to move it out. And, we see that possibility in around 10 days to two weeks, but the next week will be brutally cold. We will discuss the ending of this Arctic outbreak in tomorrow's blog.

Polar Vortex Near USA

By this weekend, the Polar Vortex will be dropping south to near the USA/Canada border. As this happens, the block up north is breaking down,but it is too late. The Arctic air will already be in place, and it will be around for a while. It will be one of the ingredients for more snow.

Wednesday's Chance Of Snow

The cause of a band of snow tomorrow into Thursday is somewhat suspect. It is being caused by, what we call, jet dynamics. Strong winds aloft in the jet stream will have these fast moving disturbances flowing towards KC. We may be in this unusual zone that won't be very wide, that will produce a band of snow. If it develops, then the snowfall amounts may approach 6" near the middle of this band. Some models have no snow, as they lose these disturbances as they are hard to find anyway, and most models have 2" to 6" of snow from this band. Some of the models have these higher snowfall totals right near Kansas City. You know me: it has my attention; it has our weather team's attention.

There is a big question. Will this thing I am calling "jet dynamics" be strong enough to ignite an area of snow? Because if it does ignite, there will be a fairly thin area that gets significant snowfall amounts. This is why I titled the blog, "An unusual chance of snow on Wednesday." Our forecast would go from a dusting to an inch possible to 3" or more possible very quickly tomorrow. I am just not ready to go there yet, but it is something we will discuss in our blog tonight.

Frost Bite

It is dangerously cold out there. Bundle up and wear lots of layers as frostbite and hypothermia are a strong possibility for longer exposure to this cold.

Kansas City Weather Timeline:

  • Today: Cloudy with a few very light snow flurries. North winds 5-15 mph causing wind chills below zero. High: 10°
  • Tonight: Cloudy with a few snow flurries. Wind chills 10 below zero. Low:
  • Wednesday: Cloudy with a 60% chance of snow. Accumulations are possible. High: 11°

Thank you for spending a few minutes of your day reading the Action Weather Blog. Have a great Tuesday. Tomorrow we will begin searching for an end to this potentially record-breaking long cold wave, and I will begin that discussion on 41 Action News tonight.