The Weather Channel’s severe weather expert, Dr. Greg Forbes, has colon cancer and will be off the air for several weeks. The news was posted on his Facebook page this morning by David Clark, president of television at The Weather Channel. The cancer was detected early on and has not spread.

“During a routine annual physical, Greg was diagnosed with colon cancer, and he will have surgery this week,” Clark said. “Doctors believe that the cancer was discovered early, and they are very positive about his prognosis.”

In a separate message, Forbes added: “The blood test in my annual physical showed that my iron level was about 20% low. This prompted my physician to prescribe additional tests to try to find out why, including a colonoscopy. The colonoscopy revealed a cancerous growth. Additional tests have not shown any evidence that the cancer has spread to other organs, so the prognosis is good.”

The Weather Channel’s team of severe weather experts Greg Postel, Jim Cantore, Mike Bettes, and Carl Parker will fill in for Forbes following his surgery, Clark said.

Forbes’ is the architect of The Weather Channel’s popular “TOR:CON” index, which ranks the daily tornado threat on a 0-10 scale by region. The Weather Channel will continue broadcasting TOR:CON during Forbes’ absence.

Even during recovery, Forbes says he intends to post severe weather updates on his Facebook page. His surgery is Friday afternoon and he will be hospitalized until Monday.

“I do plan to resume my posting of severe weather forecasts once I’m home and able,” he said.

The Weather Channel will begin airing a public service announcement about the importance of annual doctor visits today, Forbes said.

“In it I urge everyone to see their doctor annually for a physical exam. Were it not for the blood test during my physical exam, I might not have realized that I had cancer until it was too late.”