-Alaska Air expects its quarterly profit to be at the low end of its previous forecast, as high fuel costs and operational challenges weigh on margins, the U.S. carrier said on Monday.

Refinery outages on the U.S. West Coast have tightened fuel supplies and lifted prices. Alaska now expects to pay up to $2.55 per gallon, up from its earlier projections of about $2.45 per gallon.

Alaska also flagged weather and air traffic control issues driving up costs such as passenger compensation and crew overtime expenses.

Operational disruptions have increasingly pressured U.S. carriers this year, with storms and strained air traffic control capacity leading to costly disruptions across the industry.

Alaska was also hit by a major IT outage in July that disrupted hundreds of flights and stranded thousands of passengers during the peak summer travel season.

The airline later linked the outage to a faulty software update.

Alaska now expects its third-quarter adjusted profit per share at the lower end of its previously issued forecast of $1 to $1.40.

The airline, however, pointed to improving revenue trends on the back of strong premium demand and a rebound in corporate bookings.

It said unit revenue, a key gauge of pricing power, was tracking toward the upper end of its prior forecast.