Hi Carol,
Congratulations on the nice pictures.

Your title had a question mark in it and I thought I'd chime in with my non-expert opinion.

I took quite a few pictures of black widows last year and I think that is almost certainly a western black widow female, perhaps in the last instar before it is fully mature.

The little bit of yellow present in the hourglass is seldom present in the pictures of black widows on the web. I wondered why the black widows I was seeing had it and considered the possibility that some of the widows in my yard might be very darkly colored brown widows because of it. In one case, I can tell you for sure that the spider with a similar hourglass was a black widow because I watched it over time and it produced a black widow egg sac and not the spikey brown widow egg sac.

The little swoosh on the front that you can just see in your pictures is typical I suspect of black widow females before they mature completely. I think it might be that most or perhaps all black widow females lose the swoosh and the yellow in the hourglass after they have reached full maturity.