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http://imgur.com/a/57JkM#0 more pictures here

Here is a link that might be useful: pictures

From this altitude the weed looks like dallisgrass. It's so hard to get out that we've started suggesting the nuclear option - Round Up. Spot spray the weed and it will kill the bermuda right there, too. But the bermuda will come back.

You are mowing too high. It should be no higher than 1.5 inches.

Find the Bermuda Bible online and memorize it.

Try "Celsius" it is like a miracle herbicide. The second picture is St. Augustine grass. Round-up for that.

Overall, the lawn looks pretty good. Bermuda can be cut as high as 2 in. from what I've learned. The key is cutting every 4-5 days, no matter what height. Not just weekly. Keep it fed every 6 weeks. Try to get 1 inch of water on it every week. 1 inch at a time. Do not water 1/3 of an inch, 3 times per week. That will end up causing disease (and more work). Do some research on some pre-emergents (what and when to apply). Aerate in the spring or fall (your choice)

The last step is important... DON'T PARK YOUR CAR(S) ON THE GRASS!!! :)

DO WORK!

I missed the link to the rest of the pictures.
Some thoughts about what I see...

#2 is St Augustine with the beginning of some disease on it
#4 is mostly crabgrass
#6 is dallisgrass
#12 is much healthier St Augustine
#next to last is mostly crabgrass

If you want to kill the St Augustine, any weed killer affects it. You don't have to go with something like Round Up. In fact if you simply stop watering the St Aug it will die out completely.

On the other hand, if you want to convert over to a full St Augustine lawn, you can do that slowly or quickly. Write back if you want to do that. St Aug can be a lot less hassle than bermuda.

Crabgrass comes in because the soil was too moist for too long in an area where the turf was thin in the spring. Could be caused by daily watering or even by Mother Nature. The cure is to not water like that, make sure you are mowing low on a frequent basis, and regular fertilizer. The grass has to be dense with relatively dry soil to keep the crabgrass out.

Alabama your yard doesn't look bad at all you don't want to go crazy killing weeds in this heat.be patient hand pick the major ones and don't spray until your yard goes dormant than you can use round up and get a hold on them.then you need to get on pre emergent program.i like stonewall- Prodiamine it's a spring and fall application.
Read the Bermuda bible and follow by seasons.
I made mistake spraying weeds in the summer before but I guess you live and learn.
One more thing do your yard a great service and get a soil test.i see people with high ph and putting down lime.thats a killer.
I see people with low phos ,potassium,just putting nitrogen on there yard instead of a balanced fertilzer like 13-13-13.
My neighbor had a light green colored yard.one day he ask me what I was putting on my yard.i told him a balanced fertilzer.So I put a one foot square spread of 13 -13 - 13 on his yard and his grass turned bright green and grew great.He listen to me after that and had soil tested low phos,potassium and they told him to use a balanced fertilzer 19-19-19 at 5 lbs per 1000 sq ft.now his whole yard is green and he is a happy camper.
Soil test will tell you a lot of good info. Good luck. Tom