A thin layer of subfreezing temps about 5000' above the ground could allow some raindrops to freeze as they fall through the atmosphere late tonight and early Friday morning. While the sight of these ice pellets might be exciting, there will not be enough sleet to cause travel problems. Air temperatures will stay several degrees above freezing so road will NOT become icy in southeast Texas.
Different story farther west. Up to 10" of snow could fall in far west Texas. Some light snow could accumulate as far east as the Hill Country. But that rain/snow line will stay well north and west of the Houston area.
The rain will still be moving through on Saturday and it could be wet for tailgating ahead of Saturday's Texans game. Temperatures will still be cool, only hitting the low 50s by kickoff.