Convective Outlook
http://www.convectiveoutlook.com/highrisk/spc.htm
List of SPC High-Risk Days
http://en.wikipedia.org/wiki/List_of_SPC_high-risk_days
This list goes back to 1984.
The last time Houston area was in high risk was on December 23, 2002. The other time that occurred was on February 10, 1998. Both occurred in winter for Southeast Texas. The 2002 event was no bust far as I remember.