NBC's Weather Channel bid is half equity: source

The group, which also includes private equity firm Bain Capital, is seen as the leading bidder for the Weather Channel with a total offer of about $3.5 billion, the source said.

Blackstone's GSO Capital -- a hedge fund firm specializing in leveraged debt that Blackstone bought earlier this year -- will provide about $600 million in debt, the source said.

The deadline for bids was May 23, and a decision was expected this week.

Time Warner Inc (TWX.N) is also in the running, another source familiar with the matter told Reuters last week.

Privately held Landmark Communications, which put the channel up for sale along with other businesses, had originally sought $5 billion for the asset, sources have said.

NBC declined to comment, while Landmark was not immediately reachable for comment.

Weather Channel's time-sensitive broadcasts and programming about hot-button issues on the environment have proven to be attractive to audiences and advertisers, analysts say.

The network produces national, regional and local weather-related programs and has more than 96 million U.S. subscribers. It can be seen in more than 97 percent of all cable TV homes nationwide.

Along with NBC, CBS Corp (CBS.N) was also deemed a top bidder, but another source familiar with the auction last week said that appeared increasingly unlikely. CBS last week bought Web media company CNET Networks Inc (CNET.O) for $1.8 billion.

For General Electric Co's (GE.N) NBC, the Weather Channel could be combined with its own digital weather network, NBC Weather Plus.

The Weather Channel's website attracts about 35 million unique users each month, Landmark has said. That puts it among the Web's 20-most-popular sites, and the top destination for online weather, news and information.

Landmark's interest in selling it comes amid broader shifts in the cable TV landscape. Sundance Channel, a venture owned by CBS, NBC and Sundance founder Robert Redford, was sold to Cablevision Systems Corp CVC.N for $496 million this month.

Discovery Communications, which includes the Discovery Channel, Science Channel and Animal Planet networks, is expected to become a publicly traded company this quarter.

In addition, IAC/InterActiveCorp (IACI.O) is spinning off its HSN shopping network as part of a larger restructuring, and E.W. Scripps Co plans to split into two publicly traded companies, one centered on its cable channels and another that will include its newspapers and broadcast TV stations.

(Editing by Braden Reddall)