Here's why it's been so foggy lately in Michiana

 

It was another foggy morning across Michiana Wednesday, with multiple schools issuing two-hour delays to deal with the low visibility.

Why does it seem like the fog will not leave us alone in Michiana lately? It has to do with our recent weather, the time of year, and the type of land we live near.

For starters, for fog to form, the atmosphere needs a source of moisture. Sometimes, that can be humid air that a southerly wind will bring up into Michiana. This time around, our recent rainfall made the ground really wet. Once the sky clears at night, the temperature cools close to the dew point, and fog develops.

One thing that can super charge how dense fog gets is evapotranspiration from plants and crops.

Evapotranspiration is the evaporation from the ground combined with the transpiration from plants. Roots take up water from the soil, which is then drawn up the stem to the leaves. Some of that water evaporates from the leaves, adding to the humidity in the air.

So, the more crops in a particular area (especially during the fall around harvest time) the denser the fog will be. This is why fall fog is especially bad in rural areas as opposed to in, for example, downtown South Bend.

September dense fog has been a bit of a feast or famine for Michiana in the past few years. In 2019, we had four days of dense fog in September. Then, fog has not been an issue each of the last two Septembers.

South Bend has already recorded three days of dense fog this month, and we’re not even halfway done with September.

We have averaged around five days of dense fog throughout the meteorological fall season (September, October, and November).

Patchy dense fog is possible once again Thursday morning before mother nature gives us a break this weekend.