From the Spaceflight Meteorology Group:

The National Weather Service has issued a Tornado Warning for Harris County including Ellington Field until 3:00 PM.  The main JSC campus is NOT in the warning. The probable tornado was located about 4 miles northeast of Ellington moving away to the east. Ellington Field and Sonny Carter Facility will likely be dropped from the warning area shortly.  Strong winds and heavy rain will continue for about another 30 minutes or so.