From the Spaceflight Meteorology Group:

The National Weather Service has issued a Flash Flood Watch that includes JSC and vicinity until 7PM CDT.

Showers and thunderstorms will be increasing in coverage as daytime heating warms the atmosphere in combination with an upper level trough moving through.  Measureable rainfall has occurred at JSC for 9 straight days resulting in fairly saturated soils so any rain should quickly runoff and could cause some minor street and creek flooding for brief periods.  Since May 16 total rainfall at JSC has been 6.24 inches.

JSC is on the southern edge of the Flash Flood Watch area today.  It does look like the better chance for any heavy rains will be north of JSC and Ellington Field, but continue to monitor the weather for possible heavy rains. Rain chances decrease markedly tomorrow and into the weekend.