Topography's role in winter weather in the Heartland - KFVS12 News & Weather Cape Girardeau, Carbondale, Poplar Bluff

Topography's role in winter weather in the Heartland

(Source: Stock image/Pixabay) (Source: Stock image/Pixabay)
(KFVS) -

As you probably know, the Heartland has a wide range of topography from the flat Mississippi Delta to the rolling hills of the Ozarks.

But did you know this difference in topography could play a role in the type of wintry weather you may experience?

Here's how:

One of the most common impacts we see with topography across the Heartland can be seen just about every night we have a clear evening with clear skies and that's called cold air drainage or cool air drainage.

Low-lying areas experience this on many clear calm nights. The ridgetops cool down. That cool air is very heavy and it begins to seep into the river valleys and it kind of pools up.

Those low-lying areas can be up to 10 degrees cooler than the ridgetops. You'll notice this on summer evenings a lot. While driving, your car thermometer will be much warmer on ridge tops than in the valleys on clear calm evenings.

Topography also plays a role in wintry weather in those deep river valleys we have.

Southerly winds aloft will bring in warm moist air from near the Gulf of Mexico. Sometimes this warm air will move over ridge tops while sub-freezing air is trapped in the valleys. The result from this will be freezing rain.

Another winter type of precipitation that can be impacted by topography is snow.

On rare occurrences, the air mass will be extremely cold aloft. This will cause snow levels to be around 1,000 feet above sea level.

So as the snow falls below 1,000 feet in elevation it begins to melt. Snow will reach the ridge tops but fall as rain in the valleys.  Again, this doesn't happen as often as other impacts, but topography can have a huge impact on the weather where you live.

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