Freezing Rain is Likely Tonight

As many of you have probably seen already, a winter weather advisory is in effect for the northern portions of our coverage area tonight. Below is a map of all the warning active as of 8:15PM CST Saturday, February 10th.

In purple is our winter weather advisories. In general, the advisories are for ice accumulations of 1 to 2 tenths of an inch and up to 2 inches of snow, depending on where you live. For exact advisory conditions, consult the local weather service.

Let's break this down a bit to see my thinking as a forecaster here at Metro Weather Watch. The first thing I like to look at is the most recent atmospheric soundings. Unfortunately, there is no weather balloon launch from Paducah, so we have to look a bit north and a bit south. Below, we have soundings from Lincoln, IL and Nashville, TN, respectively.

Taking a look at these soundings, I have highlighted the freezing line in pink. In the northernmost profile, temperatures are below freezing throughout the atmosphere. Moving south, the lowermost portion is well above freezing, so Nashville will probably see rain.

From these soundings, we can likely expect a precipitation gradient from snow up north, transitioning to sleet, freezing rain, and then finally rain as we move south. Since we have an idea of what we're looking for, let's go ahead and take a peek at the model data.

One problem. The models vary significantly. How will we decide which to use? We can take a look at doppler radar, and then compare the initialization of each model run. Unfortunately enough, we may find that none of them are perfect, and we may need to use our meteorology skills to predict the bias and correct it for our forecast.

Here is the 8:30 PM radar (~2:30 Universal Time):

We can see that there are some showers across Western, Central, and South-Central Kentucky. The radar is picking up some spotty areas of mix near Evansville, but this is likely ground scatter and not actual precipitation.

The NAM does an okay job of initializing, but it is still very much overdone compared to the current radar. Let's check the GFS.

The GFS does alright as well, but still very much overdone. We'll try one last model, then make our decision of which to use.

This last model is the HRRR. It is only good on the short term, but it is usually very accurate. It is much higher resolution than both the previous models.

The HRRR seems to have the best initialization of this system. We will need to tone it down a bit, though, as the freezing rain and sleet in Southern Illinois is not a thing.

Now we'll use the HRRR to get an idea of freezing rain accumulations.

In our coverage area, ice accumulations remain minimal. The pinks represent approximately 1/10" of accumulation. Since this was a bit overdone in initialization, the totals are also likely overdone.

My thinking is that a majority of you will NOT see any ice accumulations tonight. However, those of you in the dark gray to pink colors, I believe you'll probably see anywhere from a trace (slick spots on bridges and overpasses) to about .05" of ice accumulation. Some spots in Southern Illinois could see up to 1/10" of accumulation, but these amounts should remain isolated.

Either way, stay wary if you go anywhere tomorrow morning, the roads could be a bit slick! Bridges and overpasses freeze at a much higher temperature than the road does. Have a great night!

-Avery