Update:
Galveston roads are almost completely empty. Hwy 146 (freeway on the west border of Galveston Bay) is also empty all the way up to at least Baytown. I-45 gulf freeway is nearly empty all the way up from Galveston to almost Loop 610(a few miles southeast of downtown.) Southwest freeway nearly empty at Beltway 8 on the west side of Houston.
Still stacked up on all the freeways to the west and north, but traffic has begun moving faster in the last hour or two. Outbound side roads out those directions also clogged, but the rear of the backup is advancing north and west. Keep in mind, the evac plan wasn't designed for a 100% evac of the metro, just 100% of the lowlying areas. Those in suitable buildings 60 miles or more inland might be ok staying. La Porte officials believe 80% of town has evacuated.
I-45 contraflow open, I-10 soon to open, Hwy 290 still not open because bottlenecks in Giddings and Brenham are not yet cleared. Some pissant counties out to the west don't have their act together and haven't been able to implement their portions of the statewide evac plans. Huge backup in Fulshear because the lights are on their normal cycle and the town police can't be bothered to direct traffic. Guess he's too busy "Blocking the bridge"?
Biggest unforseen headache seems to be the shutdown of nearly all gas stations. Since the evac plans didn't anticipate a full evacuation of the metro, it appears they weren't treated as essential services. Rolling gas resupply fleet was part of the plan, but it may not be enough. Wonder if officials will commandeer closed gas stations that still have inventory. Let the Libertarians bitch all they want about that. Those stranded who don't get gas will be taken to shelters. Still nearly 36 hours of evacuation time left.
According to Channel 11 in Houston, IF the current track holds Conroe could be looking at 75 mph sustained winds, hurricane winds maybe as far west as Sealy. Baytown could see 90-100mph, downtown Houston 75-90mph. 1 in 4 pine trees could be blown down in the metro.
Some possible suggestions:
Head southwest along the coast and turn north or west. In fact Harlingen/Brownsville, Laredo, (and maybe even Corpus depending on what happens the next 12-24 hours) might be the best place to head to. You can always sleep in your car, but a lot easier to do so without hurricane winds.
If you must evac using I-45, 290, I-10, etc., perhaps wait a few more hours and see if the lines start to lessen. If you are stuck in traffic(congrats on being online in your car!) towards the rear of the backup and starting to run low on gas, pull over for a few hours to conserve gas and let the backup drain down. Things will most likely start moving faster over the next few hours as contraflow takes its effect and others have been scared off from trying to get in line to get out.
But remember, a direct hit on Galveston is still about the highest possibility, at 24% (chance of a landfall within 50 miles either way.) Port Arthur is at 21%, Corpus at 19%, and New Orleans still at 16%. The models are still divergent, so there is NO guarantee that the track will continue to move east, and may at some point move west again. There are 2 different highs affecting this track, and the solid ridge is going to break at some point.