Inversion To Blame For Cloudy Friday

SOUTH BEND, IN - The forecast called for a break in the cloud cover by the afternoon, the sunshine allowing the temperatures to warm-up to at least 40°.  However, the afternoon hours came and went as the dense cloud cover limited even the slightest amount of sunshine to poke through.  So, what is to blame for the lack of sunshine this Friday?  The answer is what meteorologists call a "temperature inversion."

On a typical day, the warmest air is at the surface.  The temperature then cools with altitude as you get farther from the surface.  An inversion is the opposite of that.  It's when there is a layer of the atmosphere where the air temperature rises with altitude when cold dense air remains at the surface.  With the cold air at the surface, warmer air isn't able to burn off the cloud cover in a typical afternoon, which is why the clouds stuck around as shown in Fig. 1.  A temperature inversion usually occurs when there is cooling of the air at the surface overnight or by snow-pack.

Cloud cover has dominated the month of January.  Fig. 2 shows just that with 20 out of the 23 days at least partly cloudy, leaving just 3 days of sunshine for Michiana.  Chief Meteorologist Tom Coomes is calling for the clouds to stick around for the weekend.  Check out the ABC57 First Warning Neighborhood forecast here.