From the NWS:
Hurricane Harvey is expected to be a major category 3 hurricane by the time it makes landfall on the central Texas coast Saturday morning. It will weaken to a tropical storm by Sunday, before moving back offshore early next week as a tropical storm and moving towards the upper Texas or southwest Louisiana coastline. It is too early to say how strong this system will be by the second landfall next week, so stay tuned!
The big message right now is the long duration, dangerous heavy rains that are expected across our region. The heaviest rain is expected to start Sunday and continue through Thursday, with storm totals ranging from 12 to 20 inches in southeast Texas, 9 to 15 inches in southwest Louisiana, and 7 to 11 inches in central and south central Louisiana. People should be making preparations now for these floods.
Storm surge will also be a problem, with water 1 to 3 feet above ground level in parts of coastal sections of southeast Texas and southwest Louisiana, and 1 to 2 feet in south central Louisiana. The timing of the deepest water will be during high tide Saturday morning, around 630 am, but it could last through the Saturday evening high tide around 630 pm.
Gusty winds of 25 to 35 mph are possible along coastal sections of southeast Texas and southern Louisiana late Friday into Saturday.
The tornado threat is extremely low at this point.