Another roller-coaster ride, enjoyable but dopey, from Jan De Bont (Speed), this one is blown up to Cecil B. De Mille proportions, with loads of special effects. Nearly all the major characters are tornado chasers in Oklahomarival teams of scientists eager to test their equipment to learn more about how tornadoes work. Much of the action is fill-in-the-blanks, and there’s something that passes lamely for a romantic triangle involving one of the scientists (Bill Paxton), his coworker and ex-wife (Helen Hunt), and his fiancee (Jami Gertz). But the engineering of the special effects is fairly impressive, and the sight of so many objects and creatures being buffeted about carries a certain apocalyptic splendor. The script was written by Michael Crichton and Anne-Marie Martin. With Cary Elwes and Lois Smith. PG-13, 113 min. (JR)