Where’s the snow? Why we saw freezing drizzle instead
Snow has been hard to come by in Mid-Missouri for most of the winter. Mid-Missouri has seen its fair share of wintry weather this year, with icy conditions winning out more often than snow. It’s the icy conditions that once again are proving difficult for many on the roadways across Mid-Missouri.
Winter weather is one of the more difficult forecasts to nail, as it requires a combination of factors coming together for snow to occur. Add in the fact that Mid-Missouri lies in the battleground area this winter, where warmer air and colder air are battling it out, and it’s a twist that can make forecasting a challenge. As meteorologists, we’ll never be 100 percent accurate in our forecasts, but we learn from our mistakes and assess past events to become better forecasters. As meteorologists, we rely on weather models to predict the state of the atmosphere at any given time. Information derived from the current state of the atmosphere is fed into weather models and through a series of complex calculations, we get a model of what the atmosphere will look like over the coming days. Through a series of pattern recognition and an understanding of how the atmosphere works, our job is to relay what will happen over the course of a week. Meteorology is an imperfect science and there will always be things to learn, readjust and improve, which ultimately make us better forecasters.
This weekend is an example of a forecast that was quite challenging for Mid-Missouri. While freezing drizzle and rain was expected for Mid-Missouri, we never saw the changeover to snow that was expected. It’s here where we as meteorologists usually assess a situation and look for what happened and why. So, why did Mid-Missouri see all freezing drizzle and no changeover to snow?
What you’re looking at in the above picture is a sounding of the atmosphere Saturday evening at 6 PM in Kansas City. Each day, weather offices across the nation release weather balloons into the air. These weather balloons give a vertical profile of the atmosphere — or atmospheric conditions — at the time the balloon was launched. Looking at weather balloon information from nearby offices gives us an idea of what the atmospheric profile will likely be in Columbia. For reference, the red line is temperature and the green line is the dew point of the atmosphere. The dark blue line is a reference point that the entire atmosphere is below freezing, as you move away from the surface of the earth. There is a slight inversion, but the temperature never jumps above freezing which would indicate snow for the region, but that’s not the case. For snow to form, you need a nuclei for the snowflakes to build upon. This usually happens between -10 and -20 degrees Celsius, a sweet spot for snowflakes known as the dendritic growth zone. Saturation of the atmosphere is depicted by the green line and red line close together; it’s also where clouds in the atmosphere are located. Where the two diverge is when cloud tops have been reached and drier air is taking over. In the above sounding, you can see where the clouds top out near -6 to -7 degrees Celsius before the dreaded dry air takes over. It’s this dry air that limited clouds from deepening and snow to occur.
Freezing rain at the onset of the event was to be expected for Mid-Missouri, but weather models were depicting a deepening of clouds as the upper level energy pulls through the region. The deepening of clouds would mean that the transition to snow would occur, with many areas potentially seeing upwards of an inch of snow. That didn’t occur though, as cloud tops didn’t deepen as expected until early Sunday morning.
The current sounding for Kansas City as of 6 AM Sunday shows that cloud tops have finally deepened enough for that sweet spot, but unfortunately the system has all but pushed through. A very narrow band of snow is tracking through Mid-Missouri and will bring a dusting of snow to the region along and north of Interstate 70. Once the system tracks through, be advised that icy conditions will stick around.
Stay with ABC 17 News as we continue to bring you the latest impacts on the icy roads and follow us on Twitter @ABC17Stormtrack.
