at 10:10 AM by Pierce Larkin

WxRecap: Freezing Fog

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To say that the weather was weird yesterday morning is to state something that is very obvious. Many of us woke up to a fairly normal sight: fog. Fog forms at the surface when the air becomes saturated and remains at the surface. This is often forced underneath an inversion, and that is what was present across the region yesterday. The reason this can’t lift is because the cool, condensed air has no where to rise to, as the inversion acts as a cap on top of the surface.

The model forecast sounding over Bowling Green yesterday. It depicts the freezing fog set up excellently. h/t pivotalweather.com
The model forecast sounding over Bowling Green yesterday. It depicts the freezing fog set up excellently. h/t pivotalweather.com

This formed a layer of very thick fog…but below freezing? That is an entity called freezing fog, and it does some cool stuff. Freezing Fog is just fog when temperatures are below freezing. It is extremely rare in Bowling Green. I went through the depths of the Bowling Green Airport (KBWG), and out of 562,565 observations since 1997, only 537 observations had an observation containing “FZFG”, the abbreviation for freezing fog.  Yes, that is only 0.095% of observations having an observation of freezing rain.

h/t giphy.com
h/t giphy.com

Less than a tenth of a percent of observations in Bowling Green’s weather records! This is absurd. And of those 537 obs, 99 came yesterday. 18.5% of all Freezing Fog observations in KBWG’s history came YESTERDAY.

When you see these stats... h/t giphy.com
When you see these stats…
h/t giphy.com

This freezing fog then went on to produce light snowfall across the region. The fog covered the region in light mist, which fell as snow and Rime Ice. Rime ice is just the rapidly freezing of supercooled water droplets to surfaces, and that is exactly what we saw across Bowling Green yesterday. The freezing fog deposited the supercooled droplets on all surfaces. The fog eventually became so saturated with water vapor that it produced light snowfall. Some of the images from across the region are incredible.

The roads were very slick across the region, and caused traffic struggles in Bowling Green. Luckily, the fog lifted as the morning went on, and the day actually went on to be pretty nice!

Just a bit about the statistics. All data is courtesy of the Iowa Mesonet data archive. The reporting has changed since the first report in 1948. Initially, reports were sent on an hourly basis from the airport. However, within recent times, reports are made every 5 minutes automatically, and are reported. This inflates the number of observations, but still. Out of totaling 537 observations out of 562,565 TOTAL observations in the station’s history? We saw an incredibly rare event yesterday.