From the Spaceflight Meteorology Group:

At 10 AM CDT, Tropical Storm Marco was located at 20.9N 85.3W or 895 miles southeast of JSC, moving north northwest at 12 MPH. Maximum sustained winds were 65 MPH.

A gradual turn toward the northwest and west-northwest is expected to begin Sunday afternoon and continue through Tuesday morning.  On the forecast track, Marco’s center will move through the Yucatan Channel into the southeastern Gulf of Mexico by this evening.  Marco will then move across the central Gulf of Mexico on Sunday and approach the central and northwestern Gulf coast on Monday and Tuesday.  Marco is forecast to weaken to a tropical storm as it enters the northwestern Gulf prior to a landfall.  Impacts to JSC could begin as early as Monday evening but more likely Tuesday morning.

Tropical Weather Info from National Hurricane Center:

http://www.nhc.noaa.gov