This short study refines the thunderstorm stability indices values used to predict the infrequent development of thunderstorms at Vandenberg AFB and develops new thunderstorm forecast parameters. It uses data from November 2004 through April 2006, with emphasis on the second and third weeks of February 2005 and March 2006. The study includes nine days on which thunderstorms were observed within 10nm of Vandenberg AFB. The study investigates three indices, TT, LI, and SWEAT, that are used in conjunction with a newly developed lapse rate based on the height of the -20^o C, -10^oC and 0^oC temperature levels to forecast thunderstorms at Vandenberg AFB.