Subzero temperatures, winter storms and icy roads are prompting many Americans to consult their travel agents about taking a trip to Mexico, Hawaii, the Caribbean, or other warm destinations. Agent Dianne Moore, vice president of the Wisconsin chapter of ASTA, for example, says many clients are desperate to get away. "'I'm freezing to death, where can I go?'" Moore said her clients will ask. "'Enough is enough. I really need a break from all this shoveling. I can't get warm. Is it warm in Mexico?'"