The government's chief forecasting gauge of future economic activity dropped for the fifth consecutive month in November, the government said Friday in a report that offered little hope the economy would recover soon.

The 1.2 percent plunge in the Commerce Department's Index of Leading Economic Indicators followed an even worse 1.3 percent drop in October. October's decline, revised from a previous estimate of 1.2 percent, was the worst since November 1987.Eight of the 11 forward-looking components of the index fell. It is designed to predict economic activity six to nine months in advance.

Three consecutive declines in the index are considered a fairly good, but not infallible, sign a recession is approaching.

The index rose slightly as recently as June, but most private economists believe the nation has already toppled into a recession.

The latest steep drop was seen as a sign the downturn would not end soon.

Pulling the index down, in order of performance, were: a decline in new orders to factories for consumer goods, a drop in prices of raw materials, a decline in the backlog of unfilled orders at factories, a fall in new orders for business investment equipment, a jump in new claims for unemployment benefits, a decline in the average workweek, a contraction in the inflation-adjusted money supply and a drop in building permits.

The only positive contributors were an increase in stock prices, a slowing in business delivery times and a slight improvement in consumer confidence following its plunge after Iraq's August invasion of Kuwait.

The various changes left the index at 139.7 percent of its 1982 base of 100, down 4.4 percent from its 146.2 percent peak in June. It has been the worst multiple-month retreat by the index since 1980, before the last recession.

The consensus of most analysts so far is that the current economic contraction will be a relatively mild one, shorter and less harsh than the 16-month 1981-82 recession, which was the worst since the Great Depression.

An outbreak of war in the Persian Gulf could change that by sending oil prices soaring again, thus squelching any tendency for the economy to start growing again.

The Blue Chip Economic Indicators, a consensus forecast of 52 top economists, say the economy already is in a recession. On average, the indicators expect the gross national product to decline 1.3 percent in the September-December quarter and an additional 0.9 percent during the first three months of 1991. A recession is usually defined as at least two consecutive quarters of contraction.