We are tracking three storm systems this week. The strongest of the storm systems arrives Thursday night and lasts through the day Friday, and it looks to bring another round of wintry weather.
But before Friday, we are tracking the first storm, a weak disturbance that moves through the region tonight. There might be some light rain or drizzle or perhaps a few snowflakes.
The second storm is a weak but fast-moving storm system that zips through the Midwest on Wednesday. It will drag a significantly colder air into Missouri and Kansas during the day Thursday.
The third storm that arrives Thursday night appears stronger, and will likely bring a mix of freezing rain, sleet, snow. All the wintry precipitation eventually turns to rain. Friday's storm is already visible on satellite.
It's currently in the Bering Sea almost centered in the Bering Strait. It doesn't look like much of a storm now, but it is forecast to strengthen as it approaches the west coast of the United States by mid-week. The storm will continue to undergo a transformation. Here's what the upper level part of the storm will look like late Thursday. This is a depiction of the storm at 500 millibars or about half way up through the atmosphere around 29,000 feet.
Since nearly all upper level storms have a surface reflection, below is what that same storm is expected to look like down on the surface of the earth late Thursday night and Friday morning as it moves into Midwest.
Since surface low pressure is a regional destination for winds and winds typically blow counter-clockwise around a low-pressure area we should expect cold northerly winds to bring in sub-freezing temperatures from the north. At the same time, southerly winds will be drawn into the system from the central and southern plains, affecting states including Texas, Oklahoma, Kansas, Arkansas and Missouri.
The south wind will also draw warmer and more humid air into storm. Since warm air is lighter and less dense than cold air, the warm air is expected to ride up over the top of the cold air. Rain will likely fall through the shallow layer of air. Some of the rain drops will freeze into sleet pellets. Most of the rain, initially, Friday morning, will fall all the way to the surface as rain and freeze when it hits a surface whose temperature is 32 degrees or below. Remember freezing rain doesn't fall as frozen rain, rather it's rain that freezes after it hits a cold object.
At this point, we've issued a Weather Alert Day for Friday. More icy roads will be possible Friday morning, but we expect warmer air to change the sleet and freezing rain to all rain as the temperature warms above freezing Friday afternoon. Let's hope we can get the temperatures above freezing or judging by the amount of moisture this storm brings, this could be a big ice event. I'm not sure anyone is ready for that.