(11:50 p.m.) -- As Tropical Storm Ernesto weakens over the southeastern U.S., the Eastern Pacific's Hurricane John has escalated into a "major" Category Four storm with maximum sustained winds near 125 miles per hour, according to the National Hurricane Center.

Ships and ports of call are rarely affected during the East Pacific hurricane season, as most of the storms head away from the Mexican and Central American coasts. However, some -- like John -- turn back toward land.

Carnival Cruise Lines is the only line reporting an itinerary change at this point. Carnival Pride, which is currently sailing a charter from Long Beach, is skipping Puerto Vallarta and Mazatlan this week. The ship will call at Ensenada, San Diego and Catalina instead, and visited Cabo San Lucas yesterday instead of on Thursday.

A hurricane warning is in effect along the Pacific coast from Lazaro Cardenas to San Blas, which includes Puerto Vallarta and Manzanillo, popular ports of call (a hurricane warning means hurricane conditions are likely within 24 hours). La Paz is also under a hurricane warning. Watches and warnings for Ixtapa/Zihuatanejo and Acapulco have been canceled.

We'll keep you posted. --By Melissa Baldwin, Associate Editor