Writing.Com General Discussion

Hello.
This is my first post here.
I'm looking for a writing group where I can ask and learn and grow as a writer.
So, to my first question.
I was reading a best selling novel the other day, and I noticed the author flip-flopping back and forth from past tense to present tense.
Example:

"Following a circuitous route, checking the rearview mirror, I drove six blocks to wind up two blocks away from Maricopa Lane.
The tidy white clapboard house has periwinkle-blue shutters and blue porch posts. On the porch, a social center for the neighborhood, are four rocking chairs and a bench swing.
Sharlene rocked up from one of the chairs when we parked in her driveway. She is a large woman with a rapturous smile and a musical voice perfect for a gospel singer, which she is.
A golden retriever, Posey, rose from the porch floor to stand at her side..."

The descriptions are in present tense. The actions are in past.
Is this a common/standard thing?
I've never noticed this before.
Thank you for your time.
:)