CHICAGO » Flight cancellations and alerts for travel in Hurricane Sandy’s path are already in place, with more on tap for the weekend should the storm stay on its trajectory toward the northeastern United States.

US Airways already has canceled flights to and from Jamaica, which was hit hard by Hurricane Sandy’s 105-mph winds, knocking out 70 percent of the island’s power. The airline has canceled flights to the Bahamas.

“We are continuing to monitor the storm’s progress and will adapt the operations as necessary going forward,” said US Airways spokesman Andrew Christie. The storm already has claimed 21 lives in the Bahamas and Jamaica and is expected to hit key cities up the East Coast this weekend and early next week.

US Airways also issued a travel advisory and waived change fees for 44 airports it expects the hurricane to affect. Passengers can switch flights as soon as today until Nov. 4.

American Airlines issued a Caribbean travel policy that allows passengers to change plans to and from four Bahamas locations until Oct. 27.

“We’ll set out a travel policy once the path that the hurricane is taking is further defined,” said American Airlines’ spokeswoman Mary Frances Fagan.

Typically carriers will issue alerts on their websites and in most cases on their Facebook pages and through their Twitter accounts. Passengers can also sign up for a real-time, travel-alert text message to their phones as conditions warrant it.

Delta Airlines said it will refund canceled or significantly delayed flights out of Jamaica, Haiti and the Bahamas. Even if flights are not cancelled, the carrier will make a one-time free change to your ticket, but travel must begin no later than next weekend.

United Airlines has waived fees on trips rescheduled out of seven airports in the Bahamas as long as you travel by Oct. 31. If you hold out for a year, the change fee will be waived but you will have to pay any fare differences, according to the airline.

“We will include additional airports and dates of travel as the storm’s path is clearer,” said Charles Hobart, a United spokesman. “Meanwhile, we advise customers traveling in the next week through East Coast airports to sign up for flight status updates at United.com, where they can also find updates to our travel waiver.”

Southwest Airlines has had no cancellations and does not charge change fees as a rule. It does charge if the fares have changed, but in weather-related cases such as this, that is waived too.

Consumers should check their carrier’s websites and sign up for alerts for real-time updates.