From the Spaceflight Meteorology Group:

The NWS Houston/Galveston office has issued a Flood Advisory until 5:15 PM that includes JSC, NASA Ellington Field and Sonny Carter Training Facility.

As of 3:10 PM only 0.35″ of rain had fallen at JSC and 0.65″ at NASA Ellington Field.  Much heavier rains have fallen around LaPorte and Pearland where between 1.25 and 2.00 inches has fallen.  A line of storms moving slowly north northeast will produce more rains in those areas.  Be prepared for some ponding of water on nearby roadways when leaving JSC this afternoon, especially to our north.