Hunt for the Super Twister
Tuesday, May 11th at 8:00 p.m. on WPBT2
On May 3, 1999, one of the most powerful tornadoes ever recorded carved a path of complete destruction near Oklahoma City. To scientists, the supertwister held sobering lessons about the future for rapidly expanding cities in tornado-threatened areas. Most tornadoes form suddenly and with little warning. But now meteorologists are on the verge of a breakthrough that may solve the puzzle of how these killer storms spawn and where they are likely to strike. NOVA follows stormchasers as they probe the tornado’s deadly secrets.

Mystery of the Mega Volcano
Tuesday, May 25 at 8:00 p.m. on WPBT2
A remote lake in Southeast Asia conceals evidence of Earth's greatest volcanic cataclysm of the last 100,000 years. Miles beneath its placid surface lies a magma chamber that exploded so violently during the Ice Age that gases and ash may have encircled the globe and blotted out the sun for years on end. The Toba eruption may have helped kick the climate into an unprecedented freeze and perhaps even pushed ancestral human populations to the brink of extinction. In a classic science detective story, NOVA pieces together the clues about this great catastrophe and probes questions about human evolution and Earth's fragile ecosystems.

Visit the website at www.pbs.org/wgbh/nova.