Delta Air Lines expects to cancel more than 250 of 4,133 scheduled flights on Tuesday due to adverse weather conditions and rising cases of the Omicron variant, the airline said. Total cancellations as of 2 p.m. ET within, into, or out of the United States stood at 1,034, with 2,694 flights delayed, marking the fifth day of flight cancellations. Delta said it was working to reroute and substitute some planes. U.S. carriers canceled more than 1,000 flights on Monday after grounding thousands of planes over the Christmas holiday weekend as airlines struggled with staff shortages from COVID-19 infections and bad weather in parts of the country. Snowy weather in the Pacific Northwest on Monday contributed to the cancellation of more than 110 flights scheduled to land at Seattle-Tacoma Airport. With rising infections causing pilots and cabin crew to quarantine, airlines have been forced to cancel many flights. The average number …