Beirut — Lebanon's relative tranquillity does not mean the many dangers in this country have passed.
Renewed signs of violence are putting more pressure on United States special envoy Morris Draper, who is trying to negotiate a withdrawal of foreign forces in Lebanon.
''Beirut may be quiet,'' an American Mideast specialist here says, ''but problems elsewhere in the country show just how urgent it is that Mr. Draper succeed.''
At this point, the specialist says, the talks are in danger of bogging down and a much more high-powered American effort after the Nov. 2 American elections is needed to bring about Israeli and Syrian concessions.
If diplomacy does not bear fruit by next spring, he says, Israel and Syria might go to war. In the interim, Lebanon's civil strife may increase and the US and Western Europe may find their peacekeeping forces increasingly a target for terrorists.
These are the danger signs in Lebanon today:
* The war of attrition against Israeli soldiers in southern Lebanon. In recent days guerrillas have gotten much bolder about attacking Israeli soldiers behind the lines in southern Lebanon. A bazooka was fired at an Israeli vehicle on Oct. 31. In the past week at least three anti-Israeli attacks occurred near Sidon, prompting the Israeli Army at one point Oct. 28 to seal off the city to search for assailants. An Israeli soldier was killed on the Beirut-Damascus highway near Aleih Oct. 30.
If this keeps up, the Israeli Army may crack down harshly and collectively against the population under occupation - as has been done on the West Bank - and may go into ''hot pursuit'' of guerrillas behind Syrian lines in the Bekaa Valley.
* Assaults on peacekeeping forces. On Nov. 1 a car bomb exploded on Black Beach near Beirut International Airport, where American marines were unloading equipment. One marine and two Lebanese were injured. Last week, three Irish soldiers of the United Nations Interim Force in Lebanon were killed by gunmen near the Israeli border.
These sorts of attacks may cause Western nations - especially the US - to reconsider committing great numbers of soldiers to Lebanon. The US in particular has been strongly identified with Israel in this conflict and radical Palestinian, Syrian, and Lebanese groups could make the marines a target.
* Civil strife between rightist Phalange and leftist Druze forces. In the southern Lebanese Shouf mountains, Phalangists are trying to exert their influence and are being resisted by the primarily Druze forces of Walid Jumblatt's Progressive Socialist Party. These two have been foes since the Lebanese civil war began in 1975.
The Phalange has refused to disarm, causing much ill feeling among the already-disarmed Muslims of west Beirut. The wary Druze, therefore, are trying to keep their weapons and keep the Phalange out of their territory. Israel has been accused of arming both sides as part of its divide-and-rule strategy.
* Israeli-Syrian tension in the Bekaa. Israel increasingly is sending reconnaissance jets streaking over the Syrian Palestinian-controlled Bekaa. When Syrian forces fired anti-aircraft missiles at the jets Oct. 31, Israeli Foreign Minister Yitzhak Shamir called the act a ''grave violation'' of the Syrian-Israeli ceasefire.
Strategists perceive that if the Draper mission fails over the winter, the Israelis, perhaps in concert with the Phalangists, may choose to attack the Bekaa next spring.
Many Lebanese are confident that both the PLO and Syria want to quit the country. This might be accomplished through a simultaneous withdrawal. But Israel says it will not leave until after the Syrians and PLO depart because this would not allow it to save face. But this is not acceptable to Damascus.
These are the smoldering conflicts that Mr. Draper is trying to stamp out. But to budge Israel may take more than earnest diplomacy, it may take sustained application of pressure. And that might require intervention of the secretary of state or the US President - as was needed last summer to prevent an Israeli final assult on west Beirut.