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Weather Blog - Winter Weather Advisory: The Winter Mix Began As Snow & It Will Mix Or Change To Sleet & Freezing Rain

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Posted at 6:12 AM, Dec 29, 2020
and last updated 2020-12-29 08:28:57-05

Good morning bloggers,

A winter storm began just before 6 AM as reports of snow and a mixture were spreading into the KC metro area. It is starting as snow and a mixture of snow, sleet, and freezing rain. Here is the radar as of just before 6 AM:

5:56 AM Radar:

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The blue shade shows the snow, and the pink shows the mixture heading our way. It is starting as snow in the KC metro area and this will likely put a layer of snow below the mixture that begins falling. There will be slick spots on untreated and elevated surfaces, so bridges, overpasses, sidewalks, and driveways may become slick. If you are heading out early today, try to provide double the time it would usually take you to get to your destination.

7:30 AM Update:

The snow is now beginning to change to sleet, and farther south to freezing rain. Temperatures will be rising this afternoon, but before noon there will be slick conditions increasing. Here is the radar as of 7:22 AM:

7:22 AM Radar Showing The Mixture & Snow

There is a heavy band moving across the KC metro area at 7:30 AM. Some big snowflakes combined with sleet will accumulate during this next hour or so. And, then it will change to freezing rain. There is a huge difference between sleet and freezing rain. Sleet is frozen rain, or ice pellets, raindrops that freeze before reaching the ground. Freezing rain is liquid rain that freezes after hitting surfaces that are below freezing. Sleet and snow will accumulate faster on the ground, and that has been happening in the 6:45 to 7:45 AM hour. It is getting slick in spots!

Kansas City Weather Time-Line:

  • Now - Noon: Snow, mixing with or changing to sleet and freezing rain will continue. Slick conditions will develop with temperatures below freezing. Temperatures will be in the 20s this morning. Accumulations of a dusting to 1" of snow is possible before the changeover.
  • Noon - 3 PM: The mixture of precipitation will begin shifting north with temperatures rising to near 32°
  • 3 PM - 3 AM: Temperatures will rise to near 41° with rain increasing during the evening.

The New Year's Eve - New Year's Day Storm

500 mb flow (18,000 feet above us) Valid 6 AM December 31, 2020

We are looking at the flow aloft, around 18,000 feet above us. This is the 500 mb level, or half way up through the atmosphere in weight. Air pressure is how we measure the weight of the air above us. At the top of the atmosphere there is zero weight or 0 mb (mb stands for milibars). And, near the surface it is around 1000 mb. So, the 500 mb level is half way up in weight, but still only 18,000 feet above us. We analyze this critical level to find the center of these storm systems. This next storm is forecast to develop over Mexico in the next 48 hours, and then track our way. When storm systems of this strength, and track develop, copious amounts of moisture get tapped from the Gulf of Mexico. This may very well be a very wet end of the year, beginning of the year storm with over one inch liquid. This could produce significant amounts of ice and snow, so it has our attention.

500 mb flow forecast valid January 1, 2021 at noon

The track of this upper level low is of extreme importance to how much precipitation we will receive, and what types will fall. As the upper low tracks our way, freezing rain is likely to begin on New Year's Eve before midnight. And, then if it does take this perfect track, it would change to snow. We will need it to take this track for the changeover to snow to happen. If it tracks a bit farther west, that freezing rain/snow changeover line will also shift west. The track is still uncertain. We will go in-depth on this storm later today and tonight. For now, we have our current storm to track.

Thank you for spending a few minutes of your day reading the Action Weather Blog. Follow us on our social media feeds and we will keep you advised. Have a great day, and watch out for those slick spots.

Gary