Senior law enforcement officials said today that the growing signs of a "Summer of ’07" terror attack on the U.S. have led the FBI to dispatch dozens of agents to track down new leads across the country. The threat has also led the White House to begin a weekly meeting of senior law enforcement and intelligence officials. The group met last Friday and will meet tomorrow in the White House Situation Room at 1 p.m., according to the officials. Blotter Al Qaeda Cell in the U.S. Or On Its Way, According to New Intel The White House has described the meeting as "not urgent" and "regular," but law enforcement officials tell the Blotter on ABCNews.com the new weekly sessions, to be held every Thursday, were designed specifically to counter the summer threat. "The Thursday meetings will be regular, but the first one is tomorrow," said one official. Dozens of FBI agents have been given a two-week deadline to run down more than 700 leads on an FBI "worry list," developed in the wake of the failed attacks in London and Glasgow. The list includes some 100 specific leads in the New York area, senior law enforcement officials also told ABCNews.com. Although the White House says there is no credible, imminent threat to the United States, the origin of the intelligence that a small group of al Qaeda terrorists was headed to the United States came from a credible intelligence source, who in the past has been reliable, officials said. The source of the intelligence specified the small cell was traveling from Pakistan. The new threat comes as FBI agents were already trying to sort through a mountain of e-mails, jihadist message board postings, telephone intercepts and human source intelligence, in an effort to pluck an intelligence gem from the background of "chatter" louder than has been heard in any recent summer season. There is so much terrorist "noise" that some agents and officers have already dubbed June and July a "summer of chatter." Agents also have been running down financial leads and telephone records that could have linked several members of the recent failed London and Glasgow, Scotland incendiary bomb plots to North America. Do you have a tip for Brian Ross and the Investigative Team?