With the sitcom vanishing from the network scene, basic cable has picked up the slack. The results range from the inoffensive and amusing (“My Boys”) to the dreadful (“The Bill Engvall Show”) and unwatchable (“Tyler Perry’s House of Payne”).

Now Lifetime gets into the comedy act. “Rita Rocks” (7 p.m., Lifetime) stars Nicole Sullivan in the title role as a working mother who never puts herself first until she takes her guitar down from the garage rafters and forms a band with her perky mail carrier, Patty (Tisha Campbell-Martin), and the unemployed, wacky neighbor, Owen (Ian Gomez).

I’ve liked Sullivan since she was a regular on “MadTV,” but she’s not believable for a second as an underappreciated wife and mother of a two. Her manic style is better suited to a second-banana role or as part of a larger ensemble of equals. She seems to strain to make Rita seem real.

There are many annoying things about “Rita” – an intrusive laugh track, cliche dialogue about and between teenagers, and a sitcom plot structure that unfolds with near-metronomic rhythm. But the most phony aspect of the show is the music.

Rita dusts off a guitar after 20 idle years and she and Patty launch into “Try a Little Tenderness” in perfect harmony. This is not merely implausible; it’s terrible comedy.

There are laughs to be found in bad notes, out-of-tune instruments and discordant practice sessions. Anyone who has ever watched “School of Rock” knows that. Rita’s band performs with pitch-perfect results, first time, every time, just like those phony teenage bands in Disney movies and Nickelodeon shows. Where’s the triumph in that? It’s as if Lifetime didn’t think anyone would stick around to watch them practice and improve.

¢ “Baywatch” in the snow, the new docudrama “Ski Patrol” (7 p.m., TruTV) follows the rescue teams at resorts in Pennsylvania and Washington. With trails crowded with teenage hotdogs and first-time snowboarders, accidents abound, and some of them are life-threatening. In addition, there are avalanches and other catastrophes to avoid.

Teams ski to every accident with first-aid gear and take the victims out on specially fitted toboggans. It’s life-or-death nail-biting drama, and the skiers exude a wholesome, healthy camaraderie. But I tend to think that after you’ve seen one mountain rescue, you’ve seen them all.

Tonight’s other highlights

¢ High-school slights still upset Sarah on “Chuck” (7 p.m., NBC).

¢ Even cyborgs need tuneups on “Terminator: The Sarah Connor Chronicles” (7 p.m., Fox).

¢ Hiro gets the call on “Heroes” (8 p.m., NBC).

¢ A deal with the devil on “Prison Break” (8 p.m., Fox).

¢ “American Experience” (8 p.m., PBS, check local listings) profiles Lyndon Johnson.

¢ The documentary “The Third Monday in October” (8 p.m., Sundance) follows student-body elections in four middle schools.

¢ George H.W. Bush shows where they’re biting on “Hooked: Gone Monster Fishing” (8 p.m., National Geographic).

¢ A hip boutique becomes a crime scene on “CSI: Miami” (9 p.m., CBS).

¢ The case of a military coverup on “Boston Legal” (9 p.m., ABC).

¢ A baseball star puts steroids in his past on “Jose Canseco: Last Shot” (9 p.m., A&E).

¢ A chef and TV host throws a chatty dinner party on “Anthony Bourdain: No Reservations” (9 p.m., Travel).

Cult choice

Mel Gibson directed “Apocalypto” (7 p.m., Encore), the 2006 epic of Mayan civilization in its violent decline.