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What's An Inversion?

by Rod Hill

Bio | Email | Follow: @kgwrodhill

Posted on January 14, 2013 at 9:44 PM

Updated Tuesday, Jan 15 at 4:30 PM

As you watch the weather this week, you will often hear the meteorologist mention we have a strong inversion in place.  The word inversion refers to warmer air as you rise in elevation.

Normally, if you drive to Mt. Hood, you will encounter colder temperatures with the rise in elevation.  However this week, the opposite will be true.  Timberline had a high of 53 degrees Wednesday, while Portland stayed in the 30s.

As the warm air arrives from the Pacific, the new air mass glides over the top of the shallow cold air we feel here in the valley. The warmer air layered over the metro temperatures pins down or traps the cold air often leading to air stagnation problems.

Areas that see calm winds can stay trapped under clouds and fog for days with temperatures near freezing, while Mt. Hood enjoys sunshine and highs nearly 20 degrees warmer.

If you have any questions, please post a message on my Facebook @

KGW Meteorologist Rod Hill